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eBay Review – 1602 Serial Blue Backlight LCD Display Keypad 4 Arduino Uno R3 Mega 2560 Shield

I purchased an LCD Shield for Arduino from eBay a few weeks ago. I wanted to do a review to help others to get the shield to run on their Arduino or other microprocessor.

Overall Impression

Works as stated and is a good value. I would recommend this shield if you are in the market for a low cost shield with buttons for user input. It is a great shield to get a project going.

Overview

I am not certain who designed the original shield but I assume that it is open-source as there are many similar shields on the market. It appears that most are built from the same schematic that I found on SainSmart’s website at https://www.sainsmart.com/collections/all-for-arduino/products/lcd-keypad-shield-for-arduino-duemilanove-uno-mega2560-mega1280.

The shield uses one analog pin to determine which of the five switches the user has pressed. A series of resistors creates a voltage divider which in turn creates specific voltages for each switched pressed. The pins in use on the board are as follows.

Pin Function Pin Function
Reset Reset Button 10 LCD – Backlight
5V Power 9 LCD – Enable
Ground Ground 8 LCD – RS
A0 Buttons 7 LCD – D7
– SELECT 6 LCD – D6
-LEFT 5 LCD – D5
– UP
– RIGHT
– DOWN
4 LCD – D4
 WARNING: The shield works on 5VDC. Not all Arduinos are 5V tolerant so you may damage your Arduino if you use this shield on an Arduino with a microcontroller running on 3.3V such as the Due. If you do not know what voltage the microprocessor on your Arduino is running at, check the Wikipedia article at https://en.wikipedia.org/wiki/List_of_Arduino_boards_and_compatible_systems.

Code for Testing

The following code was found on SainSmart’s website. It was modified slightly to monitor the value of the A0 pin over the serial connection with the PC.

/*
  The circuit:
 * LCD RS pin to digital pin 8
 * LCD Enable pin to digital pin 9
 * LCD D4 pin to digital pin 4
 * LCD D5 pin to digital pin 5
 * LCD D6 pin to digital pin 6
 * LCD D7 pin to digital pin 7
 * LCD BL pin to digital pin 10
 * KEY pin to analogl pin 0
 */

#include 

LiquidCrystal lcd(8, 13, 9, 4, 5, 6, 7);

char msgs[5][16] = {"Right Key OK ",
                    "Up Key OK    ",               
                    "Down Key OK  ",
                    "Left Key OK  ",
                    "Select Key OK" };

int adc_key_val[5] ={50, 200, 400, 600, 800 };
int NUM_KEYS = 5;
int adc_key_in;
int key=-1;
int oldkey=-1;

void setup()
{
  // open the serial port at 9600 bps:
  Serial.begin(9600);
  
  lcd.clear(); 
  lcd.begin(16, 2);
  lcd.setCursor(0,0); 
  lcd.print("ADC key testing"); 

  //analogReadResolution(12);
}

void loop()
{
  adc_key_in = analogRead(0);    // read the value from the sensor 
  Serial.println(adc_key_in);
  key = get_key(adc_key_in);  // convert into key press
 
  if (key != oldkey)   // if keypress is detected
   {
    delay(50);  // wait for debounce time
    adc_key_in = analogRead(0);    // read the value from the sensor 
    key = get_key(adc_key_in);    // convert into key press
    if (key != oldkey)    
    {   
      lcd.setCursor(0, 1);
      oldkey = key;
      if (key >=0){
           lcd.print(msgs[key]);              
      }
    }
  }
 delay(100);
}

// Convert ADC value to key number
int get_key(unsigned int input)
{
    int k;
   
    for (k = 0; k < NUM_KEYS; k++)
    {
      if (input < adc_key_val[k]) { return k; } } if (k >= NUM_KEYS)k = -1;  // No valid key pressed
    return k;
}

The code does not perform any debouncing of the button presses so you may need to modify the code if it becomes a problem in your project. Another limitation is the shield and/or the code will not be able to determine if more than one switch has been pressed. I have not tested this, but my hypothesis is that the switch with the lowest resistance will be detected.

Issue with 3.3V Adruino Boards

First off, read the warning above as you may damage your Arduino if the microcontroller is running at 3.3V.

After receiving the shield from the seller, frentaly , on eBay, I pulled out my Arduino Due as it happened to be the first Arduino board that I grabbed. I ran the above code and had some strange results. Pressing the “SELECT” button did nothing. Pressing the “LEFT” button registered “SELECT” was pushed. Likewise, pressing “DOWN” registered that the “LEFT” button was pressed. The “UP” and “RIGHT” buttons worked as expected. I sent a message to frentaly as I believed there was a problem with the shield. I then observed that the resistors for the voltage divider were the correct values so I pulled out a Mega board and ran the same test sketch. I found that the LCD button shield worked as expected on the Mega board. I did some investigating and found that the microprocessor on the Due board is running at 3.3V therefore the highest voltage that may be read on any analog pin is 3.3V. I went a bit further to get a bit more information.

The table below provides some information regarding the ADC values reported on A0 with 5V and 3.3V microprocessor Arduino boards. In the table below there is not difference between no button pressed and the “SELECT” button being pressed.

Button

R ID

R (Ohms)

Total R

I

VDC

ADC 5V

ADV 3.3V

NONE R2 Open Infinite  

5

1023

1023

SELECT R6 3,300 5,250

0.000690

3.621

740

1023

LEFT R5 1,000 1,950

0.001266

2.468

505

765

DOWN R4 620 950

0.001695

1.610

329

499

UP R3 330 330

0.002146

0.708

144

219

RIGHT    

0.002500

0.000

0

0

Here are some slides which provide some details on how the buttons work on the shield.

  • No buttons pressed
  • RIGHT button pressed
  • UP button pressed
  • DOWN button pressed
  • LEFT button pressed
  • SELECT button pressed

The schematic is from the SainSmart web page referenced above.

Below is the data presented above shown in a different format.

Setting up ESP32 with Arduino IDE

I purchased a few things on eBay recently, including some ESP32s for $7.99 each from eBay seller, miniduino. I have not worked with the ESP32 but I know that it can work with the Arduino IDE and can run CircuitPython. I am familiar with the Arduino IDE so I wanted to get the ESP32 to work with the Arduino IDE so I can test them out and make certain that they work fine.

Doing a Google search on ESP32 and Arduino IDE returned many results which helped to get me going. The process for getting the ESP32 up and running is nearly the same as with the Teensy boards. The exception is that the Teensy boards have one nice executable to get things setup. The high-level steps to get ESP32 working with Arduino are the following.

  1. Install the latest Arduino IDE if you do not already have it installed. (https://www.arduino.cc/)
  2. Depending on your operating system, you may need to install the driver. I am running Windows 10 so I needed to install the driver for the Silicon Labs CP2102 from https://www.silabs.com/products/development-tools/software/usb-to-uart-bridge-vcp-drivers.
    BTW: The boards that I purchased have no markings on the CP2102 chip. I fear that the chips are counterfeit or a lower grade chip. The first one I tested works so I’ll keep my fingers crossed.
  3. Once the driver was installed, I needed install the Arduino libraries for the ESP32 by cloning the GitHub repository at https://github.com/espressif/arduino-esp32.
    NOTE: A better way it to follow the “Installation instructions using Arduino IDE Boards Manager” instructions on the GitHub page.
  4. Program the ESP32 with the blink example.
    1. Load the blink example in the Arduino IDE and modify the example to use pin 2 for the led.
/*
  Blink
  Turns on an LED on for one second, then off for one second, repeatedly.
 
  This example code is in the public domain.
 */
 
// Pin 13 has an LED connected on most Arduino boards.
// Pin 11 has the LED on Teensy 2.0
// Pin 6  has the LED on Teensy++ 2.0
// Pin 13 has the LED on Teensy 3.0
// give it a name:
int led = 2;

// the setup routine runs once when you press reset:
void setup() {                
  // initialize the digital pin as an output.
  pinMode(led, OUTPUT);     
}

// the loop routine runs over and over again forever:
void loop() {
  digitalWrite(led, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(1000);               // wait for a second
  digitalWrite(led, LOW);    // turn the LED off by making the voltage LOW
  delay(1000);               // wait for a second
}
  1. Pick the “ESP32 Dev Module” from the “Boards” menu option
  2. Select the COM port for your board
  3. Upload the program to the ESP32 by clicking the upload button then press and hold the boot button on the ESP32 board. You may release the button once the upload starts.

Pipboy 3000

OVERVIEW

My daughter wanted to cosplay as a character from Fallout 3 for Awesomecon 2018 in Washington D.C. We found Noe and Pedro Ruiz’s design on learn.adafruit.com 1 and decided to build it. She decided do this cosplay a few days before the event so it was going to be a challenge to complete it in time but we did it.

I thought getting the electronics in time was going to be the biggest challenge but the biggest challenge was reducing the time for the 3D prints. We started on Sunday and did not finish until Wednesday afternoon. (We did not print continuously so the overall print time was less but not by much.) Noe and Pedro have some tips on reducing print time and they worked in combination with tweaking the infill and layer height.

3D PRINTING

My 3D printer is the XYZprinting daVinci 1.0. The printer is a few years old now and is not the best 3D printer by far but it does a fair job. The printer only supports ABS fulfillment and XYZprinting filament cartridges. I have yet to take time to change the head to support PLA or hack the firmware so I can use other filaments. This limits me to the colors of filament that I may use in the printer. We looked for a brown or green filament to use for the Pipboy but did not find any to my daughter’s liking. We decided to print it in white and spray paint it. We found some metallic paint which seemed to work well. Additionally, we printed the screen visor in black and the LED diffuser in natural.

As a side note, I started using Simplify3D Slicing Software with the printer and it has made a world of difference with the print quality and control of the printer. The prints come out much closer to the designed measurements than the XYZprinting software could accomplish. The software gives more options than the XYZprinting software which really came in handy for this project. Noe and Pedro recommend removing some of the supports for the armband and base-main pieces. The XYZprinting software is all or nothing regarding supports but the Simplify3D software allowed me to remove some supports while leaving others in place.

HARDWARE

Noe and Pedro do a good job in the write-up but as with most build instructions, a few things are left out or are not clear. Here are a few notes that I made along the way but it is not a complete list as we were under a very restrict time constraint to get this project done. Unfortunately that means take notes and documenting issues was not a priority.

Additional Materials needed but not listed in the materials list in the overview.

  • Electronic Parts & Components
  • Tools & Supplies
    • (Optional) Hot Glue and Hot Glue Gun
    • Adhesive foam such as weatherstripping for doors and windows

Below are the connections to the 3.5″ LCD Shield that were used in our build.

PypBoy Function Pin Pin Function PypBoy
LED + 3V3 1 2 5V  
ENC A GPIO2 3 4 5V PB 1000C +
ENC B GPIO3 5 6 GND PB 1000C –
ROT 1 GPIO4 7 8 GPIO14 ENC SW
LED – GND 9 10 GPIO15  
ROT 2 GPIO17 11 12 GPIO18  
ROT 3 GPIO27 13 14 GND ROT –
ROT 4 GPIO22 15 16 GPIO23 ROT 5
  3V3 17 18 GPIO24  
  GPIO10 19 20 GND  
  GPIO9 21 22 GPIO25  
  GPIO11 23 24 GPIO8  
ENC – GND 25 26 GPIO7  

SOFTWARE

We made a few tweaks to the software but they were to change the map and display some different text on some screens and adding some missing code to change other displayed text. I plan to post those minor changes in a future post. The more major changes implemented were to get the pypboy program to launch on start and wire up the rotary encoder so we can safely shutdown the Raspberry Pi.

The shutdown code was modified from Inderpreet Singh’s code on Element14’s website2.

REFERENCES

  1. Noe and Pedro’s writeup on learn.adafruit.com: https://learn.adafruit.com/raspberry-pi-pipboy-3000
  2. Inderpreet Singh’s Shutdown Code on Element14’s site: https://www.element14.com/community/docs/DOC-78055/l/adding-a-shutdown-button-to-the-raspberry-pi-b

Glowforge

My Glowforge finally arrived this week. I pre-ordered it in October 2015 so it took a little over two years of waiting to finally get it.

I designed and printed the obligatory escutcheon for the print button. I chose to name my Glowforge Scotty in honor of James Doohan. His character was my inspiration for becoming an engineer in the first place so I felt it was fitting.


The escutcheon after being printed.


The escutcheon after removing the tape covering.

A few thoughts on the Glowforge interface.
The interface and workflow will take a bit of getting use to but I think it will be fine once I’m more familiar with it. At first I was getting frustrated as I created a PNG image to scale. When I imported it, I thought it was too small until I realized the scale is in inches not mm. Once I realized my error, I looked for an option to change it but could not find one. I attempted to find a way to scale it to the correct size but there is no option to type in the size or view the exact measurement. It is necessary to guess what size it is by looking at the ruler on the screen which is not very accurate. What I ended up doing was using the 1:1 scale printout and placing it in the Glowforge so I could attempt to scale it correctly. Once I did that, I could not figure out how to do cuts where I wanted them. I did some reading and found that an SVG is needed for cuts. I then used Inkscape to create an SVG from a modified image with only the cuts. This worked and I was able to scale it exactly. I then created another PNG file with just the engraving and uploaded both files. I still needed to scale the engraving but that was easy and not critical. Once everything looked good, I pressed the print button. The Glowforge performed the cuts but not the engraving. I then removed the cut image and clicked print again. This time the engraving was done. On my next print, I will need to see what I did wrong here so I do not make that mistake again.

Overall it was easy to use the Glowforge but I do have a few concerns. Firstly, a desktop application to prepare the print would afford a better setup experience. Secondly, it is not possible to print if your network connection is down for any reason or if Glowforge goes out of business. While it is nice to use a device this way, it does leave users vulnerable to the existence of the company and the health of the web servers.


The original PNG file I created.


A modified PNG for the cuts. This file could not be used for the cuts as PNG files may only be used for engraving. I needed to convert this file to SVG using Inkscape.


The modified PNG for the engraving.

Overall, I’m pleased with the Glowforge. I just hope that the company and the web-service run well for many years to come so I may continue to use the Glowforge.

BTW: The size of the escutcheon is 119.903 x 119.903 mm. I was not able to upload the SVG for the cuts so if you decide to use the PNG, you will need to convert it to SVG and resize it.

All Electronics LCD-101 (256×128 LCD) with Arduino

All Electronics has a rather large LCD display which will work great in a Jeopardy! like game that I am building. The display should be rather easy to use with an Arduino or Raspberry Pi but searching for Arduino or Raspberry Pi projects using the display turns up very few details. Fortunately the SED1330F datasheet is fairly well written. With some experimentation, it is possible to figure out how to get it to work. Especially helpful is table 32 in section 9.1.2. Some of the parameters need to be changed but it is a great example of how to get the display to work.

Here is a very short video of the LCD running from an Arduino UNO. The video starts with the display showing the result from the test2 function from the sample code below. I then upload the code again with the test2 function call commented out and the testDataSheetSection9 function call uncommented.

test2(511);

testDataSheetSection9();

#include 

// All Electronics LCD-101
// HG25504 with SED1330F

// LCD Pins
#define d0 14
#define d1 15
#define d2 2
#define d3 3
#define d4 4
#define d5 5
#define d6 6
#define d7 7
#define res 8
#define rd 9
#define wr 10
#define cs 11
#define a0 12

// LCD Comands
#define SYSTEM_SET  0x40
#define SLEEP_IN    0x53
#define DISP_OFF    0x58
#define DISP_ON     0x59
#define SCROLL      0x44
#define CSRFORM     0x5D
#define CGRAM_ADR   0x5C
#define CSRDIR_R    0x4C
#define CSRDIR_L    0x4D
#define CSRDIR_U    0x4E
#define CSRDIR_D    0x4F
#define HDOT_SCR    0x5A
#define OVLAY       0x5B
#define CSRW        0x46
#define CSRR        0x47
#define MWRITE      0x42
#define MREAD       0x43

// LCD Parameters
#define LCD_RES_W 256
#define LCD_RES_H 128
#define CHAR_BITS_WIDE 8  
#define CHARS_PER_LINE  32//8 bit
#define TEXT_ROWS 16

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  Serial.println("Hello world");
  delay(2000);// Give reader a chance to see the output.
  
  // Set pins for output
  setDataPinsForOutput();
  pinMode(res, OUTPUT);
  pinMode(rd, OUTPUT);
  pinMode(wr, OUTPUT);
  pinMode(cs, OUTPUT);
  pinMode(a0, OUTPUT);

  lcdReset();
  lcdInit();

  testDataSheetSection9();
  //test2(511);
}

void loop() {
  // put your main code here, to run repeatedly:
}

/*** Functions ***/

void clearGraphicsLayer() {
  // Set Start at 03E8H
  lcdWriteCommand(CSRW);
  lcdWriteData(0x03);
  lcdWriteData(0xE8);

  // Write 00H (blank data) for 8000 bytes
  lcdWriteCommand(MWRITE);
  for(int i=0; i<8000; i++) {
    lcdWriteData(0x00);
  }
}

void clearTextLayer() {
  // Set Start at 0000H
  lcdWriteCommand(CSRW);
  lcdWriteData(0x00);
  lcdWriteData(0x00);

  // Write 20H (space character) for 1000 bytes
  lcdWriteCommand(MWRITE);
  for(int i=0; i<1000; i++) {
    lcdWriteData(0x20);
  }
}

void lcdInit() {
  Serial.println("Step  3");
  //  3 Initialize LCD Sequence
  lcdWriteCommand(SYSTEM_SET);  // C
  lcdWriteData(0x30);  // P1 M0, M1, M2, W/S, IV, T/L, & DR
  lcdWriteData(0x87);  // P2 FX & WF
  lcdWriteData(0x07);  // P3 FY
  lcdWriteData(0x1F);  // P4 (C/R) Address range covered by one line
  lcdWriteData(0x23);  // P5 (TC/R) Length of one line
  lcdWriteData(0x7F);  // P6 (L/F) Frame height in lines
  lcdWriteData(0x20);  // P7 (APL)
  lcdWriteData(0x00);  // P8 (APH)
}

void lcdReset() {
  digitalWrite(res, LOW);
  // Set init state for wr & cs
  digitalWrite(wr, LOW);
  digitalWrite(cs, LOW);
  delay(50);
}

void lcdWriteCommand(byte command) {
  lcdWriteCtrl(0x05);
  lcdWriteJustData(command);
  digitalWrite(wr, HIGH); // Latch Data
  //delay(10);
}

void lcdWriteCtrl(byte ctrl) {
  digitalWrite(cs, LOW);
  digitalWrite(res, HIGH);
  
  digitalWrite(a0, ctrl & 0x04);
  digitalWrite(wr, ctrl & 0x02);
  digitalWrite(rd, ctrl & 0x01);
}

void lcdWriteData(byte data) {
  lcdWriteCtrl(0x01);
  lcdWriteJustData(data);
  digitalWrite(wr, HIGH); // Latch Data
  //delay(10);
}

void lcdWriteJustData(byte data) {
  digitalWrite(d7, (data & 0x80) == 0x80);
  digitalWrite(d6, (data & 0x40) == 0x40);
  digitalWrite(d5, (data & 0x20) == 0x20);
  digitalWrite(d4, (data & 0x10) == 0x10);
  digitalWrite(d3, (data & 0x08) == 0x08);
  digitalWrite(d2, (data & 0x04) == 0x04);
  digitalWrite(d1, (data & 0x02) == 0x02);
  digitalWrite(d0, (data & 0x01) == 0x01);
}

void setDataPinsForOutput() {
  pinMode(d0, OUTPUT);
  pinMode(d1, OUTPUT);
  pinMode(d2, OUTPUT);
  pinMode(d3, OUTPUT);
  pinMode(d4, OUTPUT);
  pinMode(d5, OUTPUT);
  pinMode(d6, OUTPUT);
  pinMode(d7, OUTPUT);
}

void testDataSheetSection9() {
  Serial.println("Running Test 2");

  Serial.println("Step  4");
  //  4 Set display start address and display regions
  lcdWriteCommand(SCROLL);
  lcdWriteData(0x00);     // P1 (SAD 1 L)
  lcdWriteData(0x00);     // P2 (SAD 1 H)
  lcdWriteData(0x80);     // P3 (SL 1)
  lcdWriteData(0x00);     // P4 (SAD 2 L)
  lcdWriteData(0x10);     // P5 (SAD 2 H)
  lcdWriteData(0x80);     // P6 (SL 2)
  lcdWriteData(0x00);     // P7 (SAD 3 L)
  lcdWriteData(0x04);     // P8 (SAD 3 H)
  //lcdWriteData(0x00);     // P9 (SAD 4 L)
  //lcdWriteData(0x30);     // P10 (SAD 4 H)
  
  Serial.println("Step  5");
  //  5 Set Horizontal Scroll position
  lcdWriteCommand(HDOT_SCR);
  lcdWriteData(0x00);
  
  Serial.println("Step  6");
  //  6 Set display overlay format
  lcdWriteCommand(OVLAY);
  lcdWriteData(0x01);
  
  Serial.println("Step  7");
  //  7 Set display off
  lcdWriteCommand(DISP_OFF);
  lcdWriteData(0x56);

  Serial.println("Step  8");
  //  8 Clear data in first layer with 20H (space character)
  clearTextLayer();

  Serial.println("Step  9");
  //  9 Clear data in second layer with 00H (blank data)
  clearGraphicsLayer();

  Serial.println("Step 10");
  // 10 Set cursor address
  lcdWriteCommand(CSRW);
  lcdWriteData(0x00);
  lcdWriteData(0x00);

  Serial.println("Step 11");
  // 11 Set Cursor type
  lcdWriteCommand(CSRFORM);
  lcdWriteData(0x04);
  lcdWriteData(0x86); 
  
  Serial.println("Step 12");
  // 12 Set display on
  lcdWriteCommand(DISP_ON);

  Serial.println("Step 13");
  // 13 Set Cursor direction - Right
  lcdWriteCommand(CSRDIR_R);

  Serial.println("Step 14");
  // 14 Write characters
  lcdWriteCommand(MWRITE);
  lcdWriteData(0x20);
  lcdWriteData(0x45);
  lcdWriteData(0x50);
  lcdWriteData(0x53);
  lcdWriteData(0x4F);
  lcdWriteData(0x4E);

  Serial.println("Step 15");
  // 15 Set cursor address
  lcdWriteCommand(CSRW);
  lcdWriteData(0x00);
  lcdWriteData(0x10);

  Serial.println("Step 16");
  // 16 Set Cursor direction - Down
  lcdWriteCommand(CSRDIR_D);
  
  Serial.println("Step 17");
  // 17 Fill square
  lcdWriteCommand(MWRITE);
  for(int i0=0; i0<9; i0++) {
    lcdWriteData(0xFF);
  }

  Serial.println("Step 18");
  // 18 Set cursor address
  lcdWriteCommand(CSRW);
  lcdWriteData(0x01);
  lcdWriteData(0x10);

  Serial.println("Step 19");
  // 19 Fill square
  lcdWriteCommand(MWRITE);
  for(int i0=0; i0<9; i0++) {
    lcdWriteData(0xFF);
  }

  Serial.println("Step 20");
  // 20 Set cursor address
  lcdWriteCommand(CSRW);
  lcdWriteData(0x02);
  lcdWriteData(0x10);

  Serial.println("Step 21");
  // 21 Fill square
  lcdWriteCommand(MWRITE);
  for(int i0=0; i0<9; i0++) {
    lcdWriteData(0xFF);
  }

  Serial.println("Step 22");
  // 22 Set cursor address
  lcdWriteCommand(CSRW);
  lcdWriteData(0x03);
  lcdWriteData(0x10);

  Serial.println("Step 23");
  // 23 Fill square
  lcdWriteCommand(MWRITE);
  for(int i0=0; i0<9; i0++) {
    lcdWriteData(0xFF);
  }

  Serial.println("Step 24");
  // 24 Set cursor address
  lcdWriteCommand(CSRW);
  lcdWriteData(0x04);
  lcdWriteData(0x10);

  Serial.println("Step 25");
  // 25 Fill square
  lcdWriteCommand(MWRITE);
  for(int i0=0; i0<9; i0++) {
    lcdWriteData(0xFF);
  }

  Serial.println("Step 26");
  // 26 Set cursor address
  lcdWriteCommand(CSRW);
  lcdWriteData(0x05);
  lcdWriteData(0x10);

  Serial.println("Step 27");
  // 27 Fill square
  lcdWriteCommand(MWRITE);
  for(int i0=0; i0<9; i0++) {
    lcdWriteData(0xFF);
  }

  Serial.println("Step 28");
  // 28 Set cursor address
  lcdWriteCommand(CSRW);
  lcdWriteData(0x06);
  lcdWriteData(0x10);

  Serial.println("Step 29");
  // 29 Fill square
  lcdWriteCommand(MWRITE);
  for(int i0=0; i0<9; i0++) {
    lcdWriteData(0xFF);
  }

  Serial.println("Step 30");
  // 30 Set cursor address
  lcdWriteCommand(CSRW);
  lcdWriteData(0x00);
  lcdWriteData(0x01);

  Serial.println("Step 31");
  // 31 Set Cursor direction - Right
  lcdWriteCommand(CSRDIR_R);

  Serial.println("Step 32");
  // 32 Write more text
  lcdWriteCommand(MWRITE);
  lcdWriteData(0x44);
  lcdWriteData(0x6F);
  lcdWriteData(0x74);
  lcdWriteData(0x20);
  lcdWriteData(0x4D);
  lcdWriteData(0x61);
  lcdWriteData(0x74);
  lcdWriteData(0x72);
  lcdWriteData(0x69);
  lcdWriteData(0x78);
  lcdWriteData(0x20);
  lcdWriteData(0x4C);
  lcdWriteData(0x43);
  lcdWriteData(0x44);  
  
  
  Serial.println("Done with Datasheet Section 9 Sample");
}

void test2(int testNum) {
  
  Serial.println("Running Test 2");

  Serial.println("Step  4");
  //  4 Set display start address and display regions
  lcdWriteCommand(SCROLL);
  lcdWriteData(0x00);     // P1 (SAD 1 L)
  lcdWriteData(0x00);     // P2 (SAD 1 H)
  lcdWriteData(0x80);     // P3 (SL 1)
  lcdWriteData(0x00);     // P4 (SAD 2 L)
  lcdWriteData(0x10);     // P5 (SAD 2 H)
  lcdWriteData(0x80);     // P6 (SL 2)
  lcdWriteData(0x00);     // P7 (SAD 3 L)
  lcdWriteData(0x04);     // P8 (SAD 3 H)
  
  Serial.println("Step  5");
  //  5 Set Horizontal Scroll position
  lcdWriteCommand(HDOT_SCR);
  lcdWriteData(0x00);
  
  Serial.println("Step  6");
  //  6 Set display overlay format
  lcdWriteCommand(OVLAY);
  lcdWriteData(0x01);
  
  Serial.println("Step  7");
  //  7 Set display off
  lcdWriteCommand(DISP_OFF);
  lcdWriteData(0x56);

  Serial.println("Step  8");
  //  8 Clear data in first layer with 20H (space character)
  clearTextLayer();

  Serial.println("Step  9");
  //  9 Clear data in second layer with 00H (blank data)
  clearGraphicsLayer();

  Serial.println("Step 10");
  // 10 Set cursor address
  lcdWriteCommand(CSRW);
  lcdWriteData(0x00);
  lcdWriteData(0x00);

  Serial.println("Step 11");
  // 11 Set Cursor type
  lcdWriteCommand(CSRFORM);
  lcdWriteData(0x04);
  lcdWriteData(0x86); 
  
  Serial.println("Step 12");
  // 12 Set display on
  lcdWriteCommand(DISP_ON);
  //lcdWriteData(0x16);

  Serial.println("Step 13");
  // 13 Set Cursor direction - Right
  lcdWriteCommand(CSRDIR_R);

  Serial.println("Step 14");
  // 14 Write characters
  writeNumbers(testNum);

  
  Serial.println("Done with Test 2");
}


void writeNumbers(int numQty) {
  byte numZero = 0x30;
  int idx = 0;
  byte data = 0x00;
  byte offset = 1;
  
  lcdWriteCommand(MWRITE);
  while(idx < numQty) {
    if(offset > 9)
      offset = 0;

    data = numZero + offset;
    lcdWriteData(data);
    
    offset++;
    idx++;
  }
}

I plan to post more information as the project progresses. I do want to mention a few things that I found out in regards to the display.

  • You may wonder if the HG25504 is single or dual-panel display. It is a one panel display. This becomes obvious when you look at the ICs on the back of the display. The columns are driven by four HD66204FC Dot Matrix LCD column driver with 80-channels. If each column was used on these chips, they could drive 320 columns. This is 64 more columns than the display has but no where near 512 columns which would be required for a dual-panel configuration.
  • Included ICs and function
    • HD66204FC (Qty 4) Dot Matrix LCD column driver with 80-channels
    • HD66205FC (Qty 2) Dot Matrix LCD common driver with 80-channels
    • SED1330F (Qty 1) LCD Controller
    • HY6264A (Qty 1) Static RAM (8K bytes)
    • KA324D (Qty 1) Quad Operational Amplifier
  • Vo (LCD Contrast Voltage) – You really do need to apply at least -10V to Vo in respect to ground. There are some posts regarding this display stating that tying it to ground is enough but it is not. I had applied a negative voltage but was only seeing something when Vo was near ground potential. I was able to initialize the LCD but could not see anything displayed. I knew the screen was initialized because with Vo being close to ground potential, I saw one or more lines on the LCD when it was initially powered up. When I initialized the LCD, the line(s) were gone. I was getting frustrated as I could not display anything on the screen after initializing it. When I finally used a different power supply, I could see that I had been doing things right.
  • Power Requirements (You may have different results)
    • LCD Contrast (-10.5VDC @ 3.5mA)
    • LCD Logic (5VDC @ 10mA)
    • Arduino Uno (5VDC @ 10mA
  • The SED1330F supports 8080 and 6800 family processors. This matters as the LCD is wired for one or the other and the control lines change function based on the wiring of the LCD. Section 2.4.3 of the datasheet specifies that SEL1 and SEL2 determine the operation. Both SEL1 and SEL2 are connected to ground on the LCD therefore it is operating in 8080 mode.

Today’s Tricorder Project Update

Ticorder

Progress has been slow on revision 2 of the TOS Tricorder. I have been working on the software, particularly the plugins for the sensors. I am currently working on the I2C sensors. I have 2 of the 8 sensors coded but found an issue with detecting the I2C devices in the init method without getting the I2C bus into a stuck state. I finally figured out this issue this morning and updated the Raspberry Pi forum post were I found the original code that I used. If you are interested, you may check out the post at https://www.raspberrypi.org/forums/viewtopic.php?f=32&t=114401.

Another quick note, I found the lambda function in Python. I may put this to some good use. I had to do something similar but found a way around it as I never stumbled on this gem. In many ways, I wish I stuck to C++ for this project but it is good to get to know yet another language.
References:
https://stackoverflow.com/questions/30325351/ioerror-errno-5-input-output-error-while-using-smbus-for-analog-reading-thr
http://www.secnetix.de/olli/Python/lambda_functions.hawk

GitLab Source: https://gitlab.com/richteel/TOSTricorder/tree/v2.0.0.0

CNC Machine

I have had a MyDIYCNC Machine sitting around for a few years now. I was having some problems with the controller boards so I set it aside and am just getting back to take another look at it. I found that one of the boards that was sent to me was indeed bad but MyDIYCNC no longer sells machines or parts. I then decided to go to Amazon and pick out a controller board to try. I picked the SainSmart CNC TB6560 3 Axis Stepper Motor Driver Controller Board & Cable. This board seems to work quite well. I have been having a bit of a time getting it to work properly in LinuxCNC but I have got it to home and move but it seems to be at 1/2 scale. I am still tweaking with the settings to see if I can get it to work 100%.

A few notes about wiring and hardware. The MyDIYCNC instructions refer to the motor which moves the Z axis carrier as the Y axis. It appears that it should really be the X axis and the table should be the Y axis. If it were the Y axis, the home position would be in the wrong corner of the machine. I played with the configuration a bit to see if I could get it to work as expected but I had no luck. Finally when I decided to try to swap the X and Y axes did home line up in the correct corner. I could have swapped A & B around on the Y motor and that may have reversed the direction of the motor but I did not want to go there. Swapping the axes made the most sense.

Here is a short video of a test of the CNC. The spindle has a ink cartage in it and is simply running the default LinuxCNC project. The drawing should be 5.3 inches wide but is only half that size.

Here are the settings for LinuxCNC.

001
Base Information

  • Machine Name: MyDIYCNC_inches
  • Axis configuration: XYZ
  • Reset Default machine units: Inch
  • Driver type: Other
  • Driver Timing Settings (The Stepper Drive Timing page on linux.org states that 150,000 ns should be used for all values however the current version of LinuxCNC has a max value of 100,000.)
    • Step Time: 100000
    • Step Space: 100000
    • Direction Hold: 100000
    • Direction Setup: 100000
  • Base Period Maximum Jitter: 9000

002
Parallel Port 1

  • Outputs (PC to Mill):
    • Pin 1: Amplifier Enable (Invert)
    • Pin 2: X Step
    • Pin 3: X Direction
    • Pin 4: Y Step
    • Pin 5: Y Direction
    • Pin 6: Z Step
    • Pin 7: Z Direction
    • Pin 8: Unused
    • Pin 9: Unused
    • Pin 14: Spindle ON (Invert)
    • Pin 16: Unused
    • Pin 17: Unused
  • Inputs (Mill to PC):
    • Pin 10: Both Limit + Home X (Invert)
    • Pin 11: Both Limit + Home Y (Invert)
    • Pin 12: Both Limit + Home Z (Invert)
    • Pin 13: ESTOP In
    • Pin 15: Unused
  • Parport Base Address: 0
  • Output pinout presets: Sherline (The value here is not important. It is actually used with the “Preset” button to load values.)

003
Options

Selections here really do not matter. I have not figured out how to use these yet. I may look into it more in the future.

004
Axis X

  • Motor steps per revolution: 800 (Steppers included with MyDIYCNC are 50 steps per revolution. The TB6560 board has the switches set for 1/16 microstepping. 50 x 16 = 800)
  • Driver Microstepping: 2.0 (Someone posted that 2 meant that microsteping was being used. I had this set to 32 earlier.)
  • Pulley teeth (Motor:Leadscrew): 1.0:1.0 (All axes are direct drive so they are all 1:1.)
  • Leadscrew Pitch: 20.0
  • Maximum Velocity: 0.4
  • Maximum Acceleration: 30.0
  • Home location: 0.125 This took awhile to get. If using the limit switches as home switches as well, we need to back the machine off so that the limit switches are not active when at home position. I choose to back them off 1/8 inch on all axes.)
  • Table travel: 0.0 to 5.5
  • Home Switch Location: 0.0
  • Home Search velocity: -0.05
  • Home Latch direction: Same

005
Axis Y

  • Motor steps per revolution: 800
  • Driver Microstepping: 2.0
  • Pulley teeth (Motor:Leadscrew): 1.0:1.0
  • Leadscrew Pitch: 20.0
  • Maximum Velocity: 0.4
  • Maximum Acceleration: 30.0
  • Home location: 0.125
  • Table travel: 0.0 to 8.0
  • Home Switch Location: 0.0
  • Home Search velocity: -0.05
  • Home Latch direction: Same

006
Axis Z

  • Motor steps per revolution: 800
  • Driver Microstepping: 2.0
  • Pulley teeth (Motor:Leadscrew): 1.0:1.0
  • Leadscrew Pitch: 20.0
  • Maximum Velocity: 0.4
  • Maximum Acceleration: 30.0
  • Home location: -0.125
  • Table travel: -4.0 to 0.0
  • Home Switch Location: 0.0
  • Home Search velocity: 0.05
  • Home Latch direction: Same

007
Almost Done

008
Do you want to quit?

Screenshot added for completeness

I plan to continue to look into what is going on with the scaling and settle on the correct settings or at least settings which will work.

Test Video

I would like to add more videos to the blog. One of the problems that I have had is the time it takes to perform post processing on videos to add different sources and information. I found the Open Broadcaster Software application and started messing around with it and found that it is quite good, once you get use to how it works. Here is my first attempt at creating a video with the software.

BTW: Yes, I totally ripped off some ideas from Adafruit. I’m not too creative so I copied what I like. I will attempt to change it but it is tough as Limor and Phil have created a very nice format for the shows that Adafruit produces. I also like Ben Heck and Dave Jones (EEVBlog) videos as well but I seem to watch more of the videos Adafruit puts out.

Here is my first recording.

Portable PI – Power Supply and Power Switch

Finally nearing the end of completing the power supply and soft latching power switch. The components have changed slightly but the principle design is the same. The components include two li-ion batteries connected in parallel with protection circuit, soft latching switch, Adafruit Powerboost 1000 with charging circuit (Product #2465) , and a Teensy 3.1. Along with the hardware components, there are two software pieces with one residing on the Teensy and the other running in the background of the Raspberry Pi.

The design utilizes a soft latching power switch has three functions. It powers the device on from an off state, signals the Teensy that the user has pressed the power button to request a shutdown, and power off. One of the main requirements besides those mentioned above is that the soft latching power switch must not draw current or very little current when in the off state. This is necessary as we do not want the batteries to be drained when the device is in the off state.

These requirements were met with a modified version of the soft latching power circuit described in my earlier post. The circuit was modified for a couple of reasons. First of all, the circuit needed to be able to operate from 3 to 4.5 VDC rather than at 5 VDC. Another reason the circuit needed to be modified is that the output was floating when off so the enable signal to the powerboost circuit would cause the power to cycle back on after a few seconds.

There are two pieces of software working together which allows the Raspberry Pi to safely shutdown when the user presses the power button. The Teensy has software which monitors the power button to see if it is pressed and monitors the USB power from the Raspberry Pi. If the user presses the power button, the Teensy changes the state of a pin on the Raspberry Pi. The Raspberry Pi has a program running in the background which checks if the logic level on the pin has changed. If the logic level changes, the script will issue a shutdown command.

The next thing was to determine the best way to know when the shutdown was complete.

Soft Latching Power Switch

The Raspberry Pi ON/OFF Power Controller that I looked at from Mosaic Industries, Inc. does a good job at 5 VDC but I need the circuit to be able to switch LiPo batteries which have a voltage range of between 2.7 and 4.35 VDC between discharged and fully charged. I looked for dual MOSFET devices which could operate in this range and found the following.

Both of these devices function at these lower voltages however I have been having some oscillation issues with these. When the button is held down to turn off the load, which is a LED, the output is switched off but it turns back on after a few seconds. I have not been able to investigate why this is happening. I suspect that I miswired something but I need to take some time to check.

The International Rectifier device seems to behave a bit better so it may be the one I use but I will need to investigate what the issue is and resolve that before I can move on. I can’t wait to wrap this project up.

If you have an idea as to what my problem may be, please leave a comment to let me know.

UPDATE – 16 May 2015

I determined the reason for the odd behavior was that the N-Channel MOSFET’s gate was floating. I was able to fix this by using a pull-down resistor of 100KΩ. Looking at the schematic, I connected the resistor between Pin 7 and ground. This pulls the gate to ground through the 330KΩ and 1KΩ resistors.