Arduino CircuitPython Raspberry Pi Pico Software Development

September Update

Another month has gone by and I am still working on the Speech Timer project. I was able to develop a solution with CircuitPython but was not happy with the end product. Perhaps it would be possible to get to a more stable version but even with all the RAM available on the Raspberry Pi Pico W, I would still run into issues with the heap becoming fragmented and not having enough free space to allocate additional space to server web pages reliably. I tried many of the tips to resolve the issue including calling garbage collection periodically. These changes helped the code run a bit longer but still ran into issues. I decided to rewrite the code in C++, using the Arduino IDE and wanted to be able to debug my code on the Raspberry Pi Pico while it was running as I ran into an issue when I changed the configuration to disable serial debugging output by not calling Serial.begin().

I made a Picoprobe and attempted to debug my code, but things were not as straight forward as they could have been, which resulted in many hours waisted.

I had followed the instructions in the getting-started-with-pico.pdf guide and used the Windows Pico SDK, but could not get debugging to work in Visual Code or the Arduino IDE. I was nearly ready to setup another PC with Linux and give that a go as I had seen folks saw that just works with no issues. I’m running Windows, which I assumed was part of the issue. I saw another Windows user who was very frustrated as well and stating that it seemed they were the only ones testing/using this in Windows. They eventually got it working although they could not figure out the root cause. Unfortunately I too got it working and have no clear indication of what the root issue was but I have an idea that there is an issue with the Windows setup scripts that needs to be addressed. If someone has Visual Code and/or Arduino IDE installed before installing the SDK, they will have issues. This may not be the fault of the SDK, it could be with the Visual Code and Arduino IDE setup but I suspect it is indeed the Pico SDK setup on Windows that is the issue.

Out of frustration, I reinstalled the Windows Pico SDK and checked Visual Code and the Arduino IDE. Magically, Visual Studio code worked but the Arduino IDE still failed. I then uninstalled the Arduino IDE, then restarted the PC. Once the PC restarted, I deleted the C:\Users\<user id>\AppData\Local\Arduino15 and C:\Program Files\Arduino IDE folders to clear out anything that was already configured. I then reinstalled the Arduino IDE and tried again and the Arduino IDE worked too.

There really is a problem with the Pico SDK but it will be difficult to fix unless someone can figure out what changed from the problem install and the fixed install. Unfortunately, I did not capture anything before so I cannot tell what went wrong.

End the end, once debugging was working, I was able to step through my code and found the issue in about 2 minutes. Too bad the debugging fiasco caused several days of wasted time trying to get the debugging working.

AI Raspberry Pi Pico Web Application Development

Quick Update

Just wanted to drop a quick update as I have not been able to post for the past few weeks. I am working on a couple of projects that I plan to write about shortly.

Speech Timer Clock

I have been working on a speech timer clock for my Toastmasters Club. I took an alpha version to a club meeting to get some feedback and took the feedback and have been making improvements to it. Below is a quick video showing a little of the clock’s operation.

Speech timer showing demo of 1 to 2 minute speech

Artificial Intelligence (AI)

I looked into CodeProject.AI Server and found it very easy to use and useful. I plan to write some examples and corrected examples that are posted on CodeProject website. I have started a GitHub Repository for the examples at

Meshtastic Raspberry Pi Software Development

Meshtastic with Raspberry Pi (Serial) – Part IV

In this part of the Meshtastic with Raspberry Pi (Serial) series, we will be writing some code to test the connection, then adding to our code to send sample data. When sending data, we will format the message to allow us to reject data if it is not formatted correctly and do some simple error detection.

A good resource, which will be used to write this code may be found on the “Raspberry Pi UART Communication using Python and C” page on the ElectronicWings site.


You need to start off by editing the cmdline.txt file to remove the console=serial0,115400 argument and value. If you don’t do this, you will see errors similar to ‘device reports readiness to read but returned no data’. More information and background is available at

On the Raspberry Pi, open a terminal window or use PuTTY to run the following command.
sudo nano /boot/cmdline.txt

Initial cmdline.txt opened in nano editor

Comment out or delete the “console=serial0,115400” in the line.

Modified cmdline.txt opened in nano editor

Once the cmdline.txt has been modified, restart the Raspberry Pi.

NOTES: If the console=serial0,115400 is missing, you skipped enabling the serial port from the raspi-config tool. Look back at the earlier posts in this series for instructions on how to enable the serial port. It is also possible that the baud rate in the command is something other than 115400 so you may see a different baud rate, which is fine, but you will need to remove that argument from the file.

Test Program

Now that the serial port is properly configured, we can write a simple program and test the T-Beam connection to the Raspberry Pi. On both Raspberry Pi boards, create a file with the following code.

UART communication on Raspberry Pi using Python
import serial
from time import sleep

ser = serial.Serial ("/dev/ttyS0", 38400)    #Open port with baud rate
while True:
    raw_data =              #read serial port
    if raw_data:
        data_len = ser.inWaiting()
        raw_data +=              #read serial port
        received_data = str(raw_data, "utf-8")
        print (received_data)                   #print received data

The code will listen for data on the serial port and will print the received data in the terminal window. Run the code on both Raspberry Pi boards by typing the following command.
sudo python

On the Android device, open the Meshtastic application and type a message and press the send button.

Meshtastic App with Phoebe sending the message "Hello Rachel"

The message will be displayed in the terminal window of the receiving Raspberry Pi device.

Message "Hello Rachel" received in the terminal window

Sample code sending and receiving data

Before using the following example, it is suggested to change the serial configuration to “Simple” and creating an additional channel named “serial”. Screenshots were taken of the Meshtastic application and placed into a Google Album. Refer to the album if you have any questions regarding what configuration values were used for this example.

The sample code will send CPU Temperature data twice per minute. Below are a few notes/requirements.

  • The data will be sent as JSON.
  • The data will be contained in a Python Dictionary with string values for the keys.
    Sample keys:
    • t: Time in UTC ISO 8601 format without milliseconds
    • nam: The host name of the Raspberry Pi
    • cput: CPU Temperature in degrees Celsius
  • Float values will be sent as formatted strings with the precession required for the application. As an example, temperature will be sent with two decimal values.
  • The total length of the message shall not exceed 200 bytes. In practice, it should be kept well below 200 bytes. This requires that the keys for the key value pairs to be kept short.

Example Code:

The following example code was written to meet the above requirements.

- References -
ISO 8601
UART communication on Raspberry Pi using Pyhton

import serial
import time
from datetime import datetime, timezone
import re
import socket
import json

def get_temp():
    with open('/sys/class/thermal/thermal_zone0/temp', 'r') as infile:
        return float( * 1e-3

# Open port with baud rate
ser = serial.Serial("/dev/ttyS0", 38400)
# Set the start time in the past so that the first data point will be sent at the startF
start = time.time() - 600
# Create a variable for the received data.
received_data = ""
# Flag for knowning if the error for T-Beam being disconnected has been displayed
no_serial = False

    while True:
        data_len = 0
        data_len = ser.in_waiting
        utc_dt =

        if data_len > 0:
            raw_data =  # read serial port
                received_data += str(raw_data, "utf-8")
                x ="\{.*\}", received_data)
                if x:
                    # PuTTY changes tab characters to spaces so we will use the pipe symbol
                    # print(F"{utc_dt.isoformat()}\tRECV\t{x[0]}")
                    received_data = ""
                if no_serial:
                    no_serial = False
            except UnicodeDecodeError:
                received_data = ""
                if not no_serial:
                    print("ERROR: The serial connection may be down")
                    no_serial = True

        if time.time() - start > 30:
            start = time.time()
            temp = get_temp()
            dat = {
                "t": utc_dt.isoformat(),
                "nam": socket.gethostname(),
                "cput": F"{temp:0.2f}",
            if len(json.dumps(dat)) < 200:
                ser.write(bytes(json.dumps(dat), "utf-8"))
                # PuTTY changes tab characters to spaces so we will use the pipe symbol
                # print(F"{utc_dt.isoformat()}\tSENT\t{json.dumps(dat)}")
                    F"ERROR: Data length is greater than 200 bytes (length={len(json.dumps(dat))})")

except KeyboardInterrupt:
# finally:
#   GPIO.cleanup()

Below is the output from both Raspberry Pi boards running the code with the same T-Beam Meshtastic settings.

Two PuTTY windows side-by-side with each connected to separate Raspberry Pi boards

An Excel workbook was put together to check the delay from transmit and receive as well as identifying packets being received out of order. Previous runs with slightly different code did contain out of order packets so it should not be assumed that packets will be received in order. Below is the Check.xlsx file that you may download.

Below are some statistics from the Check.xlsx Excel Workbook with data produced from 27 minutes runtime of the sample code.

  • pi-sensor01
    • Receive Delay (hh:mm:ss)
      • Min: 00:00:07
      • Max: 00:04:12
      • Average: 00:01:28
      • Median: 00:00:57
    • Data Received out of order: 0
    • Data Points
      • Total: 104
      • Sent: 56
      • Received: 48
    • Sent Packets Received by pi-sensor01:
      • Received: 55
      • Not Received: 1
      • Percent of Packets Received: 98.21%
  • pi-sensor02
    • Receive Delay (hh:mm:ss)
      • Min: 00:00:07
      • Max: 00:01:35
      • Average: 00:00:23
      • Median: 00:00:15
    • Data Received out of order: 1
    • Data Points
      • Total: 111
      • Sent: 56
      • Received: 55
    • Sent Packets Received by pi-sensor01:
      • Received: 48
      • Not Received: 8
      • Percent of Packets Received: 85.71%

Going Further

This is the end of this series at least for now. It was put together to provide some information with one way to send data between two Raspberry Pi devices using serial communications. There are other ways to send data using the serial port. One of the more interesting ways may be using the PROTO mode for the Meshtastic serial port. It looks like using the PROTO mode may allow for the code to setup and configure the Meshtastic device. If that is the case, it may provide much more control and standardization across connections. (Meshtastic Serial Port Configuration)

Another area to look into is how to improve the successful delivery of messages in a timely manor. It may be sending messages every 30 seconds was too fast and flooded the available channels. It may also be possible that the store and forward setting was misunderstood and caused message flooding on the channel. The devices may have been too close together to provide reliable communications. All of these things and others could be looked into to see if it is possible to create more reliable communications.

Meshtastic Raspberry Pi Software Development

Meshtastic with Raspberry Pi (Serial) – Part III

In this part of the Meshtastic with Raspberry Pi (Serial) series, we will be installing Meshtastic to the LilyGo T-Beam devices. We will then create a Meshtastic Channel on one LilyGo T-Beam and replicate the channel to the other LilyGo T-Beam. We will then wire the Raspberry Pi and LilyGo T-Beam devices.

Install Meshtastic Firmware on the LilyGo T-Beam devices

Visit the Meshtastic Web Installer at Select the following options:

  • Device: Tbeam
  • Firmware Version: Select the latest version.
    NOTE: May want to install latest beta version if you want the most stable version available.
  • Update or reinstall: Either option is fine. A reinstall may wipe out any settings that you have configured on the device but may be the best option for the first installation.
Meshtastic Web Installer

Click the “CONNECT” button

Select the serial port that the T-Beam is connected to. If you are uncertain, you may open the Windows Device Manager and look at Ports (COM & LPT), then look for “USB-Enhanced-SERIAL CH9102” or similar device to find the serial port.

Meshtastic Web Installer - Select COM Port


Meshtastic Web Installer - Install TBeam


Meshtastic Web Installer - Install

You will see the progress as it installs the firmware.

Meshtastic Web Installer - Installing
Meshtastic Web Installer - Installing 38%

When the installation is complete, click “NEXT”

Meshtastic Web Installer - Installation Complete

You may then click the X in the device dashboard to close the dashboard.

Meshtastic Web Installer - Close Device Dashboard

Repeat the steps for the other T-Beam, then close the browser.

Configure T-Beam and Create Channel

Using a mobile phone, tablet, or PC, open the Meshtastic App or Web Client. The following examples will show the Web Client and Android App.

Web Browser on a PC

It is best to use the Android application to configure the T-Beam device. The instructions provided here for the Web Browser are incomplete as I could not determine how to set some of the options that I know are available in the Android Application. These instructions are provided to demonstrate how to access the configuration from the web browser.

With the LilyGo T-Beam connected to the PC, open a browser and navigate to Click the “New Connection” button.

Web configuration main page

The “Connect New Device” dialog is shown. Click the “New device” button.

Web configuration - Select device

Select the T-Beam device from the list of devices and click the “Connect” button.

Web configuration - Connect New Device Screen with new device listed

Click the device from the device list.

Web configuration - Connect New Device Screen - Close button

The selected device will turn gray to show that it is selected. Click the X in the top right corner of the “Connect New Device” dialog to close the dialog box.

Web configuration - LoRa Configuration

Android App

If the Meshtastic application is not already installed, go to the Play Store and search for an install the Meshtastic App.

Play Store - Meshtastic App

Open the Meshtastic Application and click the gear icon in the top toolbar on the right, then click the “+” in the lower right corner to add a new Meshtastic device.

Meshtastic Devices Screen

On the T-Beam device, look for the device name on the LCD screen.

Meshtastic T-Beam LCD Screen

In the Meshtastic App, select the device name that matches the name on the T-Beam LCD Screen, in the list of available devices.

Meshtastic App - Device Link Selection List

The T-Beam device will display a Bluetooth pin on the LCD Screen.

Meshtastic T-Beam LCD Screen with Bluetooth Pin

Enter the Pin in the Bluetooth pairing request screen and click “OK”.

Meshtastic App - Enter Bluetooth Pin

Next, we need to set the region by clicking on the region dropdown.
NOTE: Make certain that the correct device is selected.

Open region dropdown list

Select your region from the list. My region is “US”, so that is what I selected.

Select region

The selected region will be displayed in the application and the T-Beam device will reboot.

Meshtastic App - Region Set

Once the device reboots, you may enter a name if you like. Do not move off this screen right away or the name may not stick. You may find that you need to reenter the name a few times before it is saved.

Meshtastic App - Change Name

Click on the hamburger menu in the upper right corner and select “Radio configuration”.

Meshtastic App - Hamburger Menu

Click on “Serial” from the “Radio configuration” menu.

Meshtastic App - Radio configuration menu

Enter the settings for the Serial Port, then click the “Send” button.

  • Serial enabled: Turn on
  • RX: Pin 13
  • TX: Pin 14
  • Serial baud rate: Selected 38400 baud but may select different rate. Make certain this matches when writing code on the Raspberry Pi.
  • Serial mode: TEXTMSG
Meshtastic App - Serial Settings

If you want a private channel, setup the channel on one device, then scan the QR Code on the other devices in the Mesh. I will not go over setting up a channel. For more information on setting up a channel, go to Meshtastic’s Channel Configuration page.

Wire Everything Up

The connection between the Raspberry Pi and the T-Beam device only requires three wires. A wire for the ground and two for the serial connection. The serial connection will cross the transmit (TX) and receive (RX) wires so that the TX from the Raspberry Pi is connected to the T-Beam RX and the Raspberry Pi RX will connect to the T-Beam TX. Below is a diagram showing these connections.

Wiring diagram for Raspberry Pi board connected to LilyGo T-Beam device
Meshtastic Raspberry Pi Software Development

Meshtastic with Raspberry Pi (Serial) – Part II

In Part I, we installed the Raspberry Pi OS and connected to the Raspberry Pi using PuTTY and VNC from another PC. In Part II, we will install Visual Code on the Raspberry Pi to allow us to code directly on the Raspberry Pi using a modern IDE.

It is not required to install Visual Studio Code. There are several options for writing programs and running them on the Raspberry Pi. It is possible to simply use the Text Editor on the desktop, Nano or VI from the terminal, or use an editor on the PC and transfer files using WinSCP.

Installing Visual Studio Code

The first thing to note is that the Chromium web browser is not going to work well on older Raspberry Pi boards. I am using a Raspberry Pi 3, so it is necessary to open a terminal and run the following command to launch the Dillo web browser:

Once the browser is open, navigate to

Dillo web browser showing the Visual Studio Code download page

Clicking on the .deb Arm32 link does nothing as the link is using JavaScript to download the correct file. We will need to get the installation package from our PC and move it to the Raspberry Pi.

On the PC, navigate to and click the .deb Arm32 link to download the installation package. Save it to a known location and remember where you saved it.

Open WinSCP and connect to the Raspberry Pi.

WinSCP Login window

If it is the first time connecting to the Raspberry Pi, you will see a Warning dialog. Click “Yes” to continue.

WinSCP Warning dialog for unknown host

Once connected, in the right pane of the WinSCP application, navigate to the desktop folder on the Raspberry Pi and in the left pane, navigate to the location of Visual Studio Code installation package on your PC. Once the locations have been selected, you may click and drag the installation package from the PC to the Raspberry Pi.

WinSCP window transferring the Visual Studio Code installation package

Once the package has been transferred, switch to VNC Viewer and you will see the file on your desktop.

Raspberry Pi desktop with Visual Studio Code installation package

Right-click on the installation package and select “Package Install” from the context menu.

Package Install on right-click context menu

Once the installation completes, you may launch Visual Studio Code from the menu by navigating to Programming > Visual Studio Code.

NOTE: You may delete the Visual Studio Code installer from the desktop if you wish.

Raspberry Pi OS Menu showing Visual Studio Code
Visual Studio first launch

I like to use the Explorer, the top icon on the left toolbar, to open a folder. From there, I may create files and folders for the project. In the screenshot below, I have created a folder named “Test” in my home folder and added a file named “”. Once I created the file, Visual Studio Code recognized that I created a Python file and prompted me to install the Python language extension.

Visual Studio Code with prompt to install Python language extension
Meshtastic Microcontroller Raspberry Pi Software Development

Meshtastic with Raspberry Pi (Serial) – Part I

In this post, I will step through getting Linux installed on a Raspberry Pi with an overview of different installations, and detailed setup on a headless installation. I will then move into connecting the Raspberry Pi to a LilyGo T-Beam device with Meshtastic Firmware, with the connection to the Raspberry Pi using a Serial Connection. Connecting one or more sensors to the Raspberry Pi, and finally sending that data to another Raspberry Pi connected to a LilyGo T-Beam.

Before Installing Linux on Raspberry Pi

There are several options for installing Linux on the Raspberry Pi. The first question to answer is, which distribution to use? There are several different distributions available for the Raspberry Pi boards. A comprehensive list of distributions available may be found at The distribution that I will be using is Raspberry Pi OS by Raspberry Pi.

The next question to answer is do we want a desktop or do we wish to run in headless mode? Installing a desktop is helpful if we wish to use the Raspberry Pi as a regular computer with a nice user interface. Installing a desktop does require more resources but makes the Raspberry Pi more useful if we wish to connect it to a display and keyboard or use VNC from another machine.

A headless mode installation is best if we only need to work from the terminal (command line) and/or we want more resources for running applications to monitor sensors or server up web pages or application program interfaces (API).

The last question to ask is what peripherals and options do we need to have configured? We know we will want the serial interface enabled, since that will be used to communicate to the LilyGo T-Beam devices. Depending on the sensors that we wish to use, we may want to enable the I2C interface.

Another option we will want is to be able to control the Raspberry Pi from another machine as we do not want to connect a monitor, keyboard, and mouse. We will need to enable SSH and VNC to allow control from another machine.

Below is a list of our installation options that we will configure.

  • Distribution: Raspberry Pi OS
  • Mode: Desktop
  • Enable SSH
  • Enable VNC
  • Enable Serial
  • Enable I2C

We have a couple of ways to enable the above configuration but we will configure all of these options from the Raspberry Pi Imager as it makes this relatively easy and quick. The toughest part is determining what the IP Address is of the Raspberry Pi when it boots up.

Required software on the Windows, Linux, or Apple PC

There is some software that we need to have on the PC in order to install the Raspberry Pi OS and control it from the PC.
If the listed software does not support your operating system, look for a similar application for your operating system.

Prepare SD Card for Raspberry Pi

  1. Insert an SD Card in your PC and note the drive letter. Make certain that the SD Card does not have anything that you wish to keep as the card will be wiped, so your information will be gone.
Windows Explorer showing drives with SD Card highlighted
  1. Open the Raspberry Pi OS Imager and click the “Choose OS” button
    In Windows, you will be prompted by the User Account Control (UAC) to continue. Select “Yes”
Raspberry Pi OS Imager window with Choose OS highlighted
  1. Select “Raspberry Pi OS (32-bit)
Raspberry Pi OS Imager - Operating System Listing
  1. Click the button in the lower right corner, with the gear icon for the advanced settings
Raspberry Pi OS Imager with Advanced Options button highlighted
  1. Set the hostname (optional but recommended)
  2. Make certain that “Enable SSH” is checked and “Use password authentication” is selected
  3. Change the password and optionally change the username
  4. Enter the settings for your WiFi connection if not using ethernet
  5. Optionally set time zone and keyboard layout
  6. Once the options have been set, click the “Save” button
Raspberry Pi OS Imager Advanced Options
  1. Click the “Choose Storage” button
Raspberry Pi OS Imager window with Choose Storage highlighted
  1. Select the SD Card identified earlier. Make certain that this is the SD Card as all data will be wiped from the selected drive and will not be able to be recovered.
Raspberry Pi OS Imager showing the list of storage devices that may be used
  1. Click the “Write” button to write the OS image to the SD Card
Raspberry Pi OS Imager window with the "Write" button highlighted
  1. If you are absolutely certain that the correct SD Card has been selected and there is no data on the card that you wish to keep, click the “Yes” button.
Raspberry Pi OS Imager window with the "Yes" button highlighted on confirmation dialog
  1. Once the image has been written to the SD Card, you may click the “Continue” button, close the Raspberry Pi OS Imager, and remove the SD Card from the PC, and insert it into the Raspberry Pi.
Raspberry Pi OS Imager  showing the "Write Successful" dialog
  1. Once the SD Card is inserted into the Raspberry Pi, connect power to the Raspberry Pi
  2. After a couple of minutes, open PuTTY on your PC and attempt to connect to the Raspberry Pi using the name provided in the advanced options of the Raspberry Pi OS Imager. In the example, “pi-sensor01.local” was used. In PuTTY, attempt to connect using the hostname provided in the image configuration.
    NOTE: If configuring another Raspberry Pi, do not use the same hostname.
PuTTY Configuration window showing the options for connecing to SSH Session
  1. Click the “Open” button after entering the hostname
  2. You may see a PuTTY Security Alert if it is the first time connecting to the Raspberry Pi. If so, click the “Accept” button.
PuTTY Security Alert window
  1. Once connected, enter the username and password that was entered in the advanced settings fo the the Raspberry Pi OS Imager.
PuTTY window showing successful terminal login
  1. Open the Raspberry Pi Configuration Tool by entering the following command:
    sudo raspi-config
  2. Select option 3, Interface Options, and press the Enter key
Raspberry Pi Configuration Tool with Interface Options selected
  1. Select option I3, VNC, and press the Enter key
Raspberry Pi Configuration Tool with VNC option selected
  1. Select Yes, to enable VNC Server, and press the Enter key
Raspberry Pi Configuration Tool confirmation for enabling VNC
  1. Select OK, and press the Enter key
Raspberry Pi Configuration Tool confirmation for enabling VNC
  1. Repeat the steps above to enable the Serial Port and any other interfaces, such as SPI and I2C that may be needed.
  2. Check if there are any other options that you may want to set or execute. Some useful options are Advanced Options > Expand Filesystem and Update.
  3. When done making changes, select Finish to exit the configuration tool.
  4. If you selected Expand Filesystem, you may want to restart the Raspberry Pi by issuing the following command:
    sudo reboot now

VNC Viewer

Check that we are able to connect the Raspberry Pi Desktop using VNC Viewer.

  1. Open VNC Viewer and connect to the hostname for the Raspberry Pi
VNC Connection Window
  1. If this is the first time you are connecting the Raspberry Pi, you will see an Identity Check dialog. Click the “Continue” button.
VNC Identity Check dialog
  1. Enter the Raspberry Pi username and password, then click the “OK” button.
VNC Viewer prompt for username and password
  1. If everything went correctly, you will be presented with the Raspberry Pi desktop.
Raspberry Pi desktop shown in VNC Viewer
CircuitPython Microcontroller Software Development

PyPortal Event Countdown Clock Mods III

Some big updates to the software for the modified PyPortal Event Countdown Clock. The UI was changed and several features added. It also seems to be more stable as it does not lock-up randomly. Let’s get into the changes.

  • Header and Footer status bars display information
    • Header
      • Temperature
        • Touch to change between Fahrenheit and Celsius
      • Time
        • Touch to change between 24 hour and 12 hour formats
      • Network Strength
    • Footer
      • Brightness
        • Touching the left side of the footer, dims the display backlight
        • Touching the right side of the footer, increases the brightness of the display backlight
        • Touching the middle of the footer, returns to auto brightness of the display backlight
      • Event of the number of events
  • Change the event displayed by touching the left of the display to show previous event or the right side to advance to the next event.
  • If an event has passed more than a day ago, they will be removed from the list of events and no longer displayed
  • The events do not need to be in order in the JSON file. They are sorted when they are loaded from the SD Card with the soonest event being displayed first.
Demo of the PyPortal Event Countdown Clock Mods

Noticed that the temperature was several degrees too high. This was due to the ADT7410 being too close to devices generating heat. I removed the ADT7410 and placed it on a small board and added a PH2 JST connector so it may be plugged into the I2C socket. This resulted in much more usable temperature reading.

PyPortal Event Countdown with temperature sensor moved off the PyPortal
ADT7410 Temperature Sensor moved to a separate board.

Adafruit PyPortal Titano

I just purchased an Adafruit PyPortal Titano, Product ID: 4444, to test out the software and see about allowing the software to be used on different sized screens. The Titano, has a 480×320 screen verses 320×240 of the PyPortal, Product ID: 4116.

The PyPortal Titano that I received had CircuitPython 5 installed, so the first order of business was to install CircuitPython 8. I started by going to the PyPortal CircuitPython Guide on Learn.Adafruit.

  1. Download the latest version of CircuitPython for the PyPortal Titano board by going to
  2. Download the UF2 file for CircuitPython 8.0.5
  3. Double click the reset button on the back of the Titano board and make certain the RGB LED turns green. If is is not green, try again.
  4. Copy the file to the PORTALBOOT drive that shows on your PC
    NOTE: Do not be concerned that the preinstalled demo no longer works. The library files are different for different versions.
  5. Download the CircuitPython 8 library files from
    NOTE: This step is optional as the required libraries are in the GitHub project files
  6. Go to GitHub and download the project files from
  7. Delete the files on the PyPortal Titano
  8. Unzip the files and copy the files in the PyPortal folder to the PyPortal Titano
  9. The PyPortal Titano will restart and the images will change between “Connecting to the Internet” and “Failed to Connect”. The images will not take up the full screen due to the difference in resolution. (Until the code is modified.) The reason it is not connecting is we need add files to an SD Card and put that into the PyPortal Titano.
  10. Copy the files in the SD_Card folder, from GitHub, and paste them into the root of a micro SD Card.
  11. While the SD Card is still in you PC, double click on the index.html file to open the configuration utility.
  12. You may choose to load the config.json file on the card or start creating a new file from scratch by adding new events.
  13. Once you are satisfied with the events, click on the “Secrets” tab and enter your Wi-Fi settings, Timezone, and Adafruit IO Account information.
  14. Once done, click the “Save JSON File” button and save it to the SD Card as config.json.
  15. Remove the card from the PC and insert it into the PyPortal Titano.
  16. Click the reset button on the back of the PyPortal Titano.
  17. If everything was done correctly, you can anticipate that the events will be displayed on the screen
PyPortal Event Countdown running on the PyPortal Titano
The application is in the upper left corner of the screen with space to the right and bottom.

You may notice from the image of the PyPortal Titano screen, the temperature is not displayed as the PyPortal Titano does not have the ADT7410 Temperature Sensor.

The next step will be to see how to detect the screen size or make it a setting in the config.json file.

CircuitPython Software Development Web Application Development

PyPortal Event Countdown Clock Mods II

I have implemented some of the items on my to do list from last week’s post and tested out a few more ideas. I have also published version 0.1 to GitHub.

I want to provide a few details on version 0.1 of the code and what is being worked for version 1.0. The two releases are very different with 1.0 being the one that I recommend you use once it is available.

Version 0.1 does automatically change the backlight brightness but it is not too dramatic therefore not very useful in my opinion. I’m disappointed by the way that turned out but plan to address it in version 1.0 with automatic and manual setting of the backlight.

Version 0.1 also freezes randomly, however I think it is a memory issue. I plan to address this by calling the CircuitPython garbage collection and/or implementing a watchdog timer. Not certain at the moment, which direction I will take but suspect that I will implement both.

Version 0.1 will also load all events, even those in the past so it is not very useful. Version 1.0 will address this by not loading past events.

The next version, 1.0, will have a different screen layout. As stated above, I wanted a way to manually control the backlighting so I have added icons at the bottom of the screen with touch target areas for increasing, decreasing, and automatic setting of the screen backlight. In order to add this as an option, I have created a 20 pixel high footer on the screen for the icons and to display brightness information. I may also display when the time is being updated as the touch interface is non-responsive during an update as it is a blocking call.

A 20 pixel header will also be included to display the time, the current event of the number of events, and a network strength indicator. The header and footer take away 40 pixels from the screen height but I think it will be worth it.

Hopefully I will finish this new version shortly and will have it available on GitHub. As you may have guessed, I will be on vacation/holiday for two weeks in about two weeks so there will not be any posts while I am away, unless it is about the vacation and I have stable enough internet to make some posts.

Desktop Application Development Raspberry Pi Software Development

Soft Latching Power Switch Revisited

This week, I have some updates revolving around the Soft Latching Power Switch, that I last wrote about eight years ago. I finally returned to the project and now have it working as I intended. I also have made some changes to the Dual Volt Amp Meter‘s Desktop software. I believe I may now have a stable usable version. Lastly, I’ve gotten started with and plan on using it to replace my old version of Eagle.

Soft Latching Power Switch

Soft Latching Switch on the bench
Soft Latching Switch on the bench connected to a Raspberry Pi Zero

I resolved a few items that I encountered previously when I attempted to use the Soft Latching Power Switch designed by Mosaic Industries to control an Adafruit 1000C. I was able to reliably control the PowerBoost 1000C using the Soft Latching circuit, one I removed R13 from the PowerBoost and placed a 200K ohm resistor between the enable and ground. R13 pulls up the enable pin to Vs so that the PowerBoost is always on, unless the enable pin is connected to ground. In my case, I wanted the opposite behavior. I wanted the PowerBoost to always be off unless the enable pin is connected to Vs.

The Soft Latching Power Switch designed by Mosaic Industries is intended to switch the 5V going into the Raspberry Pi but I wanted to use it differently by having it control turn off, or disable, the PowerBoost 1000C boost circuit. Below is a diagram showing the circuit used in this design.

Complete Circuit Diagram
Complete Circuit Diagram with the Soft Latching Circuit, Powerboost 1000C, and Raspberry Pi

The Soft Latching Power Switch is connected so that the input voltage is the Vs output of the Adafruit 1000C. The Vs output is USB voltage if USB Power is applied. If USB Power is not applied, Vs is the battery voltage. The output of the Soft Latching Power Switch output is connected to the enable pin of the Adafruit 1000C. The final connection of the Soft Latching Power Switch is the control pin, which is connected to GPIO22 (pin 15) of the Raspberry Pi.

The Adfruit PowerBoost 1000C is modified by removing the 200K ohm pull-up resistor, R13. An external 200K ohm resistor is connected between the enable pin and ground. A capacitor, around 0.01uF is placed in parallel with the resistor to prevent the PowerBoost from turning on the first time power is applied from either USB or battery. The value of the capacitor used is not critical. The first capacitor I grabbed was 0.01uF and it worked. The purpose of the capacitor is to make it look like a short from the enable pin to ground when power is first applied. If you find that it still starts from the on state rather than off state, you may need to use a higher value capacitor to provide more time for the capacitor to charge up and appear as a short to ground.

Once the circuit is put together and connected, you will need to load some scripts on the Raspberry Pi to allow the switch to shutdown the Raspberry Pi when the switch is pressed and for the Raspberry Pi to turn off the power when it shuts down. The scripts are available in the Pi-Power-Button project on GitHub.

This setup provides the following functionality:

  • Button press to turn on
  • Button press to signal to the device to shutdown
  • Long button press to force power off
  • Turn off power when the Raspberry Pi shuts down

Next Steps

  • Clean up the code now that it is working as expected
  • Possibly have one script file to handle shutdown and listening for button press
  • Design another circuit to allow similar functionality from a keyboard similar to the functionality on the HP 95lx and Psion 5 PDAs

Dual Volt Amp Meter

Made some changes on the desktop application for the Dual Volt Amp Meter project that I wrote about a few weeks ago.

I was having some issues with the software after it was running for a few hours. I would get random errors related to an index being out of bounds and could not figure out how that was possible when I am in a for loop that has the lower bound being zero and the upper bound being one less than the count of items in the list. I neglected to connect the dots that I was manipulating the list in another thread to limit the number of items in the list. The error would crop up if the timing was just right that the check on the array bounds occurred on the main thread, then the code then removed the item on the other thread. The next line in my main thread then referenced the item that was just removed, then the application would crash.

I believe I have now resolved all of those issues, so the code should be stable now. It has been running for a couple of hours so far without any issues.

Below is a capture from the application showing the button on the Soft Latching Power Switch being pressed and turning on the PowerBoost 1000C and in turn, the Raspberry Pi.

Graph from from the Dual Voltage Amp Meter
Graph from from the Dual Voltage Amp Meter showing the Soft Latching Power Switch being turned on.

I discovered by watching a video, where Alex Glow interviewed the team. I have since started working with and intend to create the Soft Latching Power Switch publicly in so others may use in their designs.

I really like what the has put together but it feels like there is much work to do to make it a product that may be used by the community. I plan to work more with and provide feedback to the team on design changes that may help users come up to speed quickly.

The only Schematic and PCB Layout tool that I have used successfully was Eagle. Once Eagle was acquired by Autodesk and moved to online subscription based licensing, I stopped updating Eagle. I’m still using Eagle 7.7.0 and would like to move on to something else. I have looked at KiCad and have it installed but have not made the commitment to start using it. Part of the reason is I have several components that I built in Eagle. I would need to start over in KiCad.

Another reason I have not moved to KiCad but am willing to move to, has to do with the parts libraries when sharing a project. I have received or pulled KiCad designs and have had to reach out to the authors to get some missing libraries. (The same is an issue with sharing Eagle designs.) solves this problem as libraries are online and may be shared with the community.

In addition to public parts, has the ability to create pull completed circuits with PCB layouts in other designs. This is great as one may design a power supply or other circuit and pull it in and reuse it in multiple projects. I have attempted something similar in Eagle but there are always issues with it and it seems you are always reinventing the wheel. eliminates redundant work and speeds up the design process.

Another advantage of is they have brought change management into the tool. You may see all the revisions made to a part or circuit, stay on an older version, or update to the latest change. This allows someone to update their public design to fix an issue and someone else who has used the design, may pull the latest fix into their design. It also allows someone to fork someone else’s design, improve upon it, then submit a pull request so the original designer can pull the change and everyone may benefit.

As you can tell, I’m very hopeful that will succeed and the Open Source community will embrace what is attempting to do with their hardware design platform. Give it a try. I hope to see the community help grow.

You may see what I’m up to on the platform by going to So far, I’ve put together one part for the IRF7319. I did so by forking another user’s part for the IRF7317.

Software Development Web Application Development

Physical File Folder Tabs – HTML Solution to Print Folder Tabs

Today, I needed to print some physical folder tabs. I wanted to challenge myself a bit to see if it were possible to build an HTML application that could do the job. Ideally, I wanted to load an Excel file and use the contents of a worksheet to create the labels. I was able to find some example code that uses some AJAX libraries from CloudFlare to parse the Excel file. With that and a few other bits of code samples, I was able to build a robust local page for creating physical folder tabs that may be printed and cut to help keep my filing tidy.

The code is available on GitHub at