Serial-a-Sketch

Powered by Python 3.10.5, pygame-ce 2.3.0.dev1, tkinter (Tk interface) and pySerial (Windows) / Python 3.8.10, pygame-ce 2.2.1, tkinter (Tk interface) and pySerial (Linux)
Code (Python script, procedural) by Kyuchumimo

There will be a Web version once pySerial will be compatible with pygbag.

"Serial-a-Sketch: A virtual mechanical drawing sketch pad.
Virtually compatible with any microcontroller. Just program your microcontroller, plug and play."

Tested on the following devices:

• USB Serial Device
• Prolific USB-to-Serial Comm Port
• USB-SERIAL CH340
• Arduino Uno

CHANGELOG 230506
A Linux version of the program has been added. This version should work perfectly on the oldest version of Ubuntu with long term support and higher, i.e. Ubuntu 20.04 LTS and higher.

This project uses real electronic components to make this project work. The materials are as follows:

Any microcontroller that can communicate to your computer via SERIAL/TTL/UART protocol, that has at least 2 internal analog-to-digital converters (or externally using some ADC IC like MCP3002/3004/3008/3202/3204/3208/3302/3304, ADS1015/1115/7830, PCF8591) and can provide a string containing a Python-like list of the values of 2 10-bit (0-1023 levels) analog signals.

x2 10k ohms rotary potentiometers

Breadboard

DuPont cables

CONTROLS

LEFT POTENTIOMETER (ANALOG-TO-DIGITAL CONVERTER, CHANNEL 0)	Stylus X-axis position
RIGHT POTENTIOMETER (ANALOG-TO-DIGITAL CONVERTER, CHANNEL 1)	Stylus Y-axis position
SPACEBAR (KEYBOARD)	Clear
ESCAPE	Close software

Code for run on any Arduino compatible board:





void setup() {
  Serial.begin(9600);
}

void loop() {
  int adc0 = analogRead(0); // 26 for Pico board
  int adc1 = analogRead(1); // 27 for Pico board

  Serial.println("[" + String(adc0) + ", " + String(adc1) + "]");

  delay(50);
}

Note: Even if you don't have an Arduino development board, the same code (using MiniCore Arduino core or equivalent) is compatible for a variety of 8-bit ATmega family microcontrollers such as ATmega8/48/88/168/328, just make sure you have a USB to SERIAL/TTL/UART converter.

For 8-bit ATtiny family microcontrollers such as the ATtiny25/45/85 (using ATTinyCore Arduino core or equivalent), you will need to implement serial communication by software with the SoftwareSerial library.
See: https://docs.arduino.cc/learn/built-in-libraries/software-serial

Code for run only on 8-bit ATmega8/48/88/168/328 microcontrollers (main.c GCC C Executable for Atmel Studio / Microchip Studio):

#define BAUD 9600
#define F_CPU 8000000UL
#define BAUD_PRESCALLER ((F_CPU / (BAUD * 16UL)) - 1)

#include <avr/io.h>
#include <util/delay.h>
#include <stdio.h>

void USART_init(void)
{
    UBRR0H = (uint8_t)(BAUD_PRESCALLER >> 8);
    UBRR0L = (uint8_t)(BAUD_PRESCALLER);
    UCSR0B = (1 << TXEN0);
    UCSR0C = (3 << UCSZ00);
}

void USART_send_char(char data)
{
    while (!(UCSR0A & (1 << UDRE0)));
    UDR0 = data;
}

void USART_send_string(char *str)
{
    while (*str)
    {
        USART_send_char(*str++);
    }
}

void ADC_init(void)
{
    ADCSRA |= (1 << ADEN);
    ADCSRA |= (1 << ADPS2) | (1 << ADPS1) | (1 << ADPS0);
}

uint16_t ADC_read(uint8_t channel)
{
    ADMUX = (1 << REFS0) | channel;
    ADCSRA |= (1 << ADSC);
    while (ADCSRA & (1 << ADSC));
    return ADC;
}

int main(void)
{
    USART_init();
    ADC_init();

    while (1)
    {
        uint16_t adc_value_0 = ADC_read(0);
        uint16_t adc_value_1 = ADC_read(1);
        char adc_string[20];
        sprintf(adc_string, "[%d, %d]", adc_value_0, adc_value_1);
        USART_send_string(adc_string);
        USART_send_string("\r\n");
        _delay_ms(50);
    }
}

Code for run on Micropython v1.17 or higher compatible boards (save as main.py):

import machine
import utime

adc0 = machine.ADC(26)
adc1 = machine.ADC(27)

while True:
    print(f"[{adc0.read_u16()//64}, {adc1.read_u16()//64}]")
   
    utime.sleep_ms(50)

Code for run on any CircuitPython v5.1.0-rc.0 o higher compatible board (save as code.py):

import time
import board
import analogio

adc0 = analogio.AnalogIn(board.GP26)
adc1 = analogio.AnalogIn(board.GP27)

while True:
    print(f"[{adc0.value//64}, {adc1.value//64}]")

    time.sleep(0.05)

TROUBLESHOOTING
GNU/Linux:
• Cannot open /dev/ttyUSB0: Permission denied

This error is caused by the user not having access to the serial ports. More specifically, the user is not in the dialout group.

Open a terminal and enter the following command:
sudo usermod -a -G dialout $USER
Make sure you log out for the changes to take effect.

• version 'GLIBC_2.31' not found

This program requires glibc 2.31 or higher, in other words, it is only compatible with Ubuntu 20.04 LTS or higher.