I have two devices:
A) arduino pro mini, powered with two AA bateries.
B) ESP32 device with a small tft screen.
I want to use the ESP32 as a mobile serial monitor to debug sensor nodes (using mysensors) without having to attach a PC. I have all the separate things working, but when I connect the two, the ESP32 does not display the serial data on screen. Proven so far:
- When I connect the ESP32 to the Serial Monitor in the IDE and I enter a message, it's displayed on the TFT screen.
- When I connect the Arduino (only the TX, RX and additional GND), still battery powered) to the Serial Monitor in the IDE it displays the message in the serial monitor.
- Both are working at 9600 baud
When I connect the two together, it doesn't work. The way I do this is as follows:
Powerbank by USB to the ESP32 device.
2AA batteries to VCC and GND on the Arduino
GND from ESP32 to GND arduino
TX (ESP32) to RX(Arduino)
But nothing works. What am I missing here?
Code Arduino:
void setup() {
Serial.begin(9600); // for serial debugging over USB.
pinMode(13, OUTPUT);
}
void loop() {
Serial.println("Ping");
digitalWrite(13, HIGH); // turn the LED on (HIGH is the voltage level)
delay(1000); // wait for a second
digitalWrite(13, LOW); // turn the LED off by making the voltage LOW
delay(1000); // wait for a second
} // end of main loop.
Code TFT:
#include <TFT_eSPI.h> // Hardware-specific library
#include <SPI.h>
TFT_eSPI tft = TFT_eSPI(); // Invoke custom library
// The scrolling area must be a integral multiple of TEXT_HEIGHT
#define TEXT_HEIGHT 16 // Height of text to be printed and scrolled
#define BOT_FIXED_AREA 0 // Number of lines in bottom fixed area (lines counted from bottom of screen)
#define TOP_FIXED_AREA 16 // Number of lines in top fixed area (lines counted from top of screen)
#define YMAX 320 // Bottom of screen area
// The initial y coordinate of the top of the scrolling area
uint16_t yStart = TOP_FIXED_AREA;
// yArea must be a integral multiple of TEXT_HEIGHT
uint16_t yArea = YMAX-TOP_FIXED_AREA-BOT_FIXED_AREA;
// The initial y coordinate of the top of the bottom text line
uint16_t yDraw = YMAX - BOT_FIXED_AREA - TEXT_HEIGHT;
// Keep track of the drawing x coordinate
uint16_t xPos = 0;
// For the byte we read from the serial port
byte data = 0;
// A few test variables used during debugging
bool change_colour = 1;
bool selected = 1;
// We have to blank the top line each time the display is scrolled, but this takes up to 13 milliseconds
// for a full width line, meanwhile the serial buffer may be filling... and overflowing
// We can speed up scrolling of short text lines by just blanking the character we drew
int blank[19]; // We keep all the strings pixel lengths to optimise the speed of the top line blanking
void setup() {
// Setup the TFT display
tft.init();
tft.setRotation(0); // Must be setRotation(0) for this sketch to work correctly
tft.fillScreen(TFT_BLACK);
// Setup baud rate and draw top banner
Serial.begin(9600);
tft.setTextColor(TFT_WHITE, TFT_BLUE);
tft.fillRect(0,0,240,16, TFT_BLUE);
tft.drawCentreString(" Serial Terminal - 9600 baud ",120,0,2);
// Change colour for scrolling zone text
tft.setTextColor(TFT_WHITE, TFT_BLACK);
// Setup scroll area
setupScrollArea(TOP_FIXED_AREA, BOT_FIXED_AREA);
// Zero the array
for (byte i = 0; i<18; i++) blank[i]=0;
}
void loop(void) {
// These lines change the text colour when the serial buffer is emptied
// These are test lines to see if we may be losing characters
// Also uncomment the change_colour line below to try them
//
// if (change_colour){
// change_colour = 0;
// if (selected == 1) {tft.setTextColor(TFT_CYAN, TFT_BLACK); selected = 0;}
// else {tft.setTextColor(TFT_MAGENTA, TFT_BLACK); selected = 1;}
//}
while (Serial.available()) {
data = Serial.read();
// If it is a CR or we are near end of line then scroll one line
if (data == '\r' || xPos>231) {
xPos = 0;
yDraw = scroll_line(); // It can take 13ms to scroll and blank 16 pixel lines
}
if (data > 31 && data < 128) {
xPos += tft.drawChar(data,xPos,yDraw,2);
blank[(18+(yStart-TOP_FIXED_AREA)/TEXT_HEIGHT)%19]=xPos; // Keep a record of line lengths
}
//change_colour = 1; // Line to indicate buffer is being emptied
}
}
// ##############################################################################################
// Call this function to scroll the display one text line
// ##############################################################################################
int scroll_line() {
int yTemp = yStart; // Store the old yStart, this is where we draw the next line
// Use the record of line lengths to optimise the rectangle size we need to erase the top line
tft.fillRect(0,yStart,blank[(yStart-TOP_FIXED_AREA)/TEXT_HEIGHT],TEXT_HEIGHT, TFT_BLACK);
// Change the top of the scroll area
yStart+=TEXT_HEIGHT;
// The value must wrap around as the screen memory is a circular buffer
if (yStart >= YMAX - BOT_FIXED_AREA) yStart = TOP_FIXED_AREA + (yStart - YMAX + BOT_FIXED_AREA);
// Now we can scroll the display
scrollAddress(yStart);
return yTemp;
}
// ##############################################################################################
// Setup a portion of the screen for vertical scrolling
// ##############################################################################################
// We are using a hardware feature of the display, so we can only scroll in portrait orientation
void setupScrollArea(uint16_t tfa, uint16_t bfa) {
tft.writecommand(ILI9341_VSCRDEF); // Vertical scroll definition
tft.writedata(tfa >> 8); // Top Fixed Area line count
tft.writedata(tfa);
tft.writedata((YMAX-tfa-bfa)>>8); // Vertical Scrolling Area line count
tft.writedata(YMAX-tfa-bfa);
tft.writedata(bfa >> 8); // Bottom Fixed Area line count
tft.writedata(bfa);
}
// ##############################################################################################
// Setup the vertical scrolling start address pointer
// ##############################################################################################
void scrollAddress(uint16_t vsp) {
tft.writecommand(ILI9341_VSCRSADD); // Vertical scrolling pointer
tft.writedata(vsp>>8);
tft.writedata(vsp);
}
