BitBastelei

Vor einiger Zeit hatte ich ein altes EC-Kartenterminal zerlegt und schon angemerkt, dass man viele der Bauteile recyclen kann. Dieses mal geht es um das Display sowie die Tastatur – eigentlich eine einfache Aufgabe. Eigentlich.

Links

• 00:00 EFTPOS
• 08:43 i2c_port_address_scanner.ino
• 09:21 https://github.com/tronixlabsAU/LCDbackpack
• 10:17 https://www.instructables.com/id/I2C-LCD-on-NodeMCU-V2-With-Arduino-IDE/
• 11:20 https://github.com/fdebrabander/Arduino-LiquidCrystal-I2C-library
• 19:40 ICS Expander MCP25S17
• 21:00 https://github.com/n0mjs710/MCP23S17
  https://github.com/adlerweb/MCP23S17

Quellcode Testsoftware #include <Arduino.h> #include <SPI.h> #include <MCP23S17.h> #include <Wire.h> #include <LiquidCrystal_PCF8574.h> extern "C" { #include "user_interface.h" } const char* kbdmap = "K##.0CRE321MSO654FTe987U"; const char* cmdmap = " +-*/"; #define ROWS 4 #define COLS 6 LiquidCrystal_PCF8574 lcd(0x27); MCP gpio(0, 15); int8_t last = 0; String num1, num2; byte cmd = 0; void setPinMode(void) { uint16_t out = 0xFFFF; out <<= (ROWS); gpio.pinMode(out); gpio.pullupMode(out); gpio.inputInvert(out); out = ~out; gpio.digitalWrite(out); } void startLCD(void) { int error; Serial.println("LCD..."); Wire.begin(D1, D2); Wire.beginTransmission(0x27); error = Wire.endTransmission(); Serial.print("Return: "); Serial.print(error); if (error == 0) { Serial.println(": LCD found."); } else { Serial.println(": LCD not found."); } lcd.begin(20, 2); // initialize the lcd lcd.home(); lcd.clear(); lcd.print("BitBa // POS-Matrix"); } void setup() { Serial.begin(115200); Serial.print("\nInit..."); gpio.begin(); setPinMode(); Serial.println("OK"); startLCD(); } int8_t checkKeys(void) { byte row, col; int input; for(row = 0; row < ROWS; row++) { gpio.digitalWrite(row, LOW); delay(1); input = gpio.digitalRead(); gpio.digitalWrite(row, HIGH); for(col=0; col < COLS; col++) { if(input & (1<<(ROWS + col))) { return (byte)(COLS * row + col); } } } return -1; } void loop() { int8_t input = checkKeys(); int8_t check = 0xFF; float result = num2.toFloat(); bool change = false; if(result == 0) result = num1.toFloat(); if(input < (COLS*ROWS) && input >= 0 && last != input) { Serial.print(input); Serial.print(": "); last = input; if(input >= 0) { check = kbdmap[input]; Serial.print(check); }else{ check = 0xFF; } Serial.println(); delay(15); //Poor maker debounce }else{ check = 0xFF; } if(check != 0xFF) { switch(check) { //K##.0CRE321MSO654FTe987U case 'K': cmd = 4; change = true; break; case 'R': cmd = 3; change = true; break; case 'S': cmd = 2; change = true; break; case 'T': cmd = 1; change = true; break; case 'C': cmd = 0; num1 = ""; num2 = ""; change = true; break; case 'U': cmd = 0; num2 = ""; change = true; break; case 'F': if(cmd == 0) { if(num1.length() > 0) num1.remove(num1.length()-1); }else{ if(num2.length() > 0) num2.remove(num2.length()-1); } change = true; break; case '#': switch(cmd) { case 1: result = num1.toFloat() + num2.toFloat(); break; case 2: result = num1.toFloat() - num2.toFloat(); break; case 3: result = num1.toFloat() * num2.toFloat(); break; case 4: result = num1.toFloat() / num2.toFloat(); break; } cmd = 0; num1 = result; num2 = ""; change = true; break; case '.': case '0': case '1': case '2': case '3': case '4': case '5': case '6': case '7': case '8': case '9': if(cmd == 0) { num1 += (char)check; }else{ num2 += (char)check; } change = true; } if(change) { lcd.clear(); lcd.setCursor(0, 0); lcd.print(num1); if(cmd > 0) { lcd.setCursor(18, 0); lcd.print(" "); lcd.print(cmdmap[cmd]); lcd.setCursor(0, 1); lcd.print(num2); } } } }

 

 

Hinweis: Der bei 19:40 gezeigter GPIO-Expander wurde mir seinerzeit von ICStation.com zur Verfügung gestellt.