Hi everybody,
We're making a miniature vending machine, driven by an Arduino MEGA. Basically consists of a TFT screen, a select & a down button to navigate the menu, 4 stepper motors that drive the spiral vending mechanism and an IR sensor to check whether the product has been vended.
However, the screen is a shield which takes up almost all of the pins on an Arduino UNO board, although digital pins 1 and 0 are free. So we decided to try and make our Arduinos communicate by linking the TX and RX pins and using Serial.
We want to send instructions to the UNO to display a certain bitmap file on the screen when a button is pressed. The code we've got so far hasn't been very successful, and we're wondering whether anybody has tried to do something similar before? Or failing that, just take a look at our code so far and tell us if there are any glaring errors we're missing.
This code has just got one button coded to try and change the screen a few times. It uploads fine but the button doesn't have any effect on the bitmap being displayed.
Master code:
int sbutton = 6; // select button
int outgoingByte; // variable for serial communication
int sbuttonState = 0;
void setup() {
Serial.begin(9600); // start serial between MEGA and UNO
pinMode(sbutton, INPUT); // define select button
}
void loop() {
sbuttonState = digitalRead(sbutton); // resets buttons to 0
while(sbuttonState ==LOW){
sbuttonState = digitalRead(sbutton);
}
if (sbuttonState==HIGH) // select button pressed
{outgoingByte==1; // How can I help? SUPPLIES comes up
Serial.write(outgoingByte);
sbuttonState = digitalRead(sbutton); //button reset
while(sbuttonState ==LOW){
sbuttonState = digitalRead(sbutton);}
}
if (sbuttonState==HIGH) // if supplies chosen
{
outgoingByte ==7; //bring up supplies menu : chocolate
sbuttonState = digitalRead(sbutton); //button reset
while(sbuttonState ==LOW){
sbuttonState = digitalRead(sbutton);
}
}
}
Screen code:
#include <SD.h>
#include "TFTLCD.h"
#define LCD_CS A3
#define LCD_CD A2
#define LCD_WR A1
#define LCD_RD A0
#define LCD_RESET A4
//Duemilanove/Diecimila/UNO/etc ('168 and '328 chips) microcontoller:
#define BLACK 0x0000
#define BLUE 0x001F
#define RED 0xF800
#define GREEN 0x07E0
#define CYAN 0x07FF
#define MAGENTA 0xF81F
#define YELLOW 0xFFE0
#define WHITE 0xFFFF
#define SD_CS 10 // Set the chip select line to whatever you use (10 doesnt conflict with the library)
// our TFT wiring
TFTLCD tft(LCD_CS, LCD_CD, LCD_WR, LCD_RD, LCD_RESET);
// the file itself
File bmpFile;
// information we extract about the bitmap file
int bmpWidth, bmpHeight;
uint8_t bmpDepth, bmpImageoffset;
//int loads = 0;
#define ROTATION 3
#define BUFFPIXEL 60
#define BYTES_PER_PIXEL 3
uint8_t picBuffer[BYTES_PER_PIXEL * BUFFPIXEL]; // 3 * pixels to buffer
int bufferIndex = BYTES_PER_PIXEL * BUFFPIXEL;
int incomingByte;
void setup()
{
Serial.begin(9600);
tft.reset();
tft.initDisplay();
tft.setRotation(ROTATION);
Serial.print("Initializing SD card...");
pinMode(10, OUTPUT);
tft.setRotation(ROTATION);
if (!SD.begin(10)) {
Serial.println("failed!");
while(1);
}
Serial.println("SD OK!");
}
/*
Callback for displayBitmap function to load data into buffer
*/
unsigned int loadBitmapData(void *data)
{
File *sdFile = (File *) data;
int bytesRead = sdFile->read(picBuffer, 2 * BUFFPIXEL);
return bytesRead / 2;
}
/*
Loads a raw 16-bit bitmap with the format
4-byte width
4-byte height
raw 16-bit pixel data in R5G6B5 format
*/
void displayBitmap(const char *name, int x, int y)
{
File sdFile = SD.open(name);
if( ! sdFile )
{
Serial.println("Error opening file.");
return;
}
uint32_t width = read32( sdFile );
uint32_t height = read32( sdFile );
Serial.print("Width: ");
Serial.println(width, DEC);
uint32_t time = millis();
uint16_t bx, ex, by, ey;
tft.setViewport(x, y, x + width - 1, y + height - 1);
tft.goTo(x, y);
int bytesRead = ( loadBitmapData(&sdFile) );
tft.bulkWrite( (uint16_t *) picBuffer, bytesRead, loadBitmapData, &sdFile);
// tft.setViewport(bx, ex, by, ey);
tft.setDefaultViewport();
Serial.print(millis() - time, DEC);
Serial.println(" ms");
sdFile.close();
}
/*
Slightly modified routine for drawing bitmaps (From original samples).
Watch out, as this one uses some global variables
*/
void bmpdraw(const char *name, int x, int y) {
File sdFile = SD.open(name);
if( ! sdFile )
{
Serial.println("Error opening file.");
return;
}
if( ! bmpReadHeader(sdFile) )
{
Serial.println("Error reading header.");
return;
}
sdFile.seek(bmpImageoffset);
uint32_t diskTime = 0;
uint32_t tempTime;
uint32_t time = millis();
uint16_t p;
uint8_t g, b;
int i, j;
Serial.print("rotation = "); Serial.println(tft.getRotation(), DEC);
tft.goTo(0,0);
for (i=0; i< bmpHeight; i++) {
// bitmaps are stored with the BOTTOM line first so we have to move 'up'
tft.goTo(0, bmpHeight - i - 1);
for (j=0; j<bmpWidth; j++) {
// read more pixels
if (bufferIndex >= BYTES_PER_PIXEL * BUFFPIXEL) {
tempTime = millis();
sdFile.read(picBuffer, BYTES_PER_PIXEL * BUFFPIXEL);
diskTime += millis() - tempTime;
bufferIndex= 0;
}
p = tft.Color565( picBuffer[bufferIndex+2], picBuffer[bufferIndex+1], picBuffer[bufferIndex]);
bufferIndex += 3;
tft.writeData(p);
}
}
uint32_t totalTime = millis();
Serial.print("Total time: ");
Serial.println(totalTime - time, DEC);
Serial.print("Disk Time: ");
Serial.println(diskTime, DEC);
sdFile.close();
}
/*
From example code. Reads bitmap header. Uses global variables.
*/
boolean bmpReadHeader(File f) {
// read header
uint32_t tmp;
if (read16(f) != 0x4D42) {
// magic bytes missing
return false;
}
// read file size
tmp = read32(f);
Serial.print("size 0x"); Serial.println(tmp, HEX);
// read and ignore creator bytes
read32(f);
bmpImageoffset = read32(f);
Serial.print("offset "); Serial.println(bmpImageoffset, DEC);
// read DIB header
tmp = read32(f);
Serial.print("header size "); Serial.println(tmp, DEC);
bmpWidth = read32(f);
bmpHeight = read32(f);
if (read16(f) != 1)
return false;
bmpDepth = read16(f);
Serial.print("bitdepth "); Serial.println(bmpDepth, DEC);
Serial.print("compression "); Serial.println(tmp, DEC);
return true;
}
/*********************************************/
// These read data from the SD card file and convert them to big endian
// (the data is stored in little endian format!)
// LITTLE ENDIAN!
uint16_t read16(File &f) {
uint16_t d;
uint8_t b;
b = f.read();
d = f.read();
d <<= 8;
d |= b;
return d;
}
// LITTLE ENDIAN!
uint32_t read32(File &f) {
uint32_t d;
uint16_t b;
b = read16(f);
d = read16(f);
d <<= 16;
d |= b;
return d;
}
void loop()
{
bmpdraw("pdt.bmp", 0, 0);
if (Serial.available() > 0) {
// read the incoming byte:
incomingByte = Serial.read();
if (incomingByte==1)
{
tft.fillScreen(WHITE);
bmpdraw("ssup.bmp", 0, 0); // 24-bit bottom-up display
delay(3000);
}
}
if (Serial.available() > 0) {
read the incoming byte:
incomingByte = Serial.read();
if (incomingByte==7)
{
tft.fillScreen(WHITE);
bmpdraw("choc.bmp", 0, 0); // 24-bit bottom-up display
delay(3000);
}
}
}
There is a lot of code in the screen code that was provided by a blogger who had used our particular ebay bought tft screen before. The screen works fine when it is programmed directly.
Apologies for this being quite long and confusing. Please do ask if I've omitted any details you'd need to know to start offering suggestions.
Thanks!
