197 lines
7.7 KiB
C++
197 lines
7.7 KiB
C++
// Reads a screen image off the TFT and send it to a processing client sketch
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// over the serial port. Use a high baud rate, e.g. for an ESP8266:
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// Serial.begin(921600);
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// At 921600 baud a 320 x 240 image with 16 bit colour transfers can be sent to the
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// PC client in ~1.67s and 24 bit colour in ~2.5s which is close to the theoretical
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// minimum transfer time.
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// This sketch has been created to work with the TFT_eSPI library here:
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// https://github.com/Bodmer/TFT_eSPI
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// Created by: Bodmer 27/1/17
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// Updated by: Bodmer 10/3/17
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// Updated by: Bodmer 23/11/18 to support SDA reads and the ESP32
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// Version: 0.08
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// MIT licence applies, all text above must be included in derivative works
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//====================================================================================
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// Definitions
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//====================================================================================
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#define PIXEL_TIMEOUT 100 // 100ms Time-out between pixel requests
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#define START_TIMEOUT 10000 // 10s Maximum time to wait at start transfer
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#define BITS_PER_PIXEL 16 // 24 for RGB colour format, 16 for 565 colour format
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// File names must be alpha-numeric characters (0-9, a-z, A-Z) or "/" underscore "_"
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// other ascii characters are stripped out by client, including / generates
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// sub-directories
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#define DEFAULT_FILENAME "tft_screenshots/screenshot" // In case none is specified
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#define FILE_TYPE "png" // jpg, bmp, png, tif are valid
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// Filename extension
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// '#' = add incrementing number, '@' = add timestamp, '%' add millis() timestamp,
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// '*' = add nothing
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// '@' and '%' will generate new unique filenames, so beware of cluttering up your
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// hard drive with lots of images! The PC client sketch is set to limit the number of
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// saved images to 1000 and will then prompt for a restart.
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#define FILE_EXT '@'
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// Number of pixels to send in a burst (minimum of 1), no benefit above 8
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// NPIXELS values and render times:
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// NPIXELS 1 = use readPixel() = >5s and 16 bit pixels only
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// NPIXELS >1 using rectRead() 2 = 1.75s, 4 = 1.68s, 8 = 1.67s
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#define NPIXELS 8 // Must be integer division of both TFT width and TFT height
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//====================================================================================
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// Screen server call with no filename
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//====================================================================================
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// Start a screen dump server (serial or network) - no filename specified
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boolean screenServer(void)
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{
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// With no filename the screenshot will be saved with a default name e.g. tft_screen_#.xxx
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// where # is a number 0-9 and xxx is a file type specified below
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return screenServer(DEFAULT_FILENAME);
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}
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//====================================================================================
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// Screen server call with filename
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//====================================================================================
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// Start a screen dump server (serial or network) - filename specified
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boolean screenServer(String filename)
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{
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delay(0); // Equivalent to yield() for ESP8266;
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boolean result = serialScreenServer(filename); // Screenshot serial port server
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//boolean result = wifiScreenServer(filename); // Screenshot WiFi UDP port server (WIP)
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delay(0); // Equivalent to yield()
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//Serial.println();
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//if (result) Serial.println(F("Screen dump passed :-)"));
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//else Serial.println(F("Screen dump failed :-("));
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return result;
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}
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//====================================================================================
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// Serial server function that sends the data to the client
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//====================================================================================
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boolean serialScreenServer(String filename)
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{
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// Precautionary receive buffer garbage flush for 50ms
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uint32_t clearTime = millis() + 50;
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while ( millis() < clearTime && Serial.read() >= 0) delay(0); // Equivalent to yield() for ESP8266;
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boolean wait = true;
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uint32_t lastCmdTime = millis(); // Initialise start of command time-out
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// Wait for the starting flag with a start time-out
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while (wait)
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{
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delay(0); // Equivalent to yield() for ESP8266;
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// Check serial buffer
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if (Serial.available() > 0) {
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// Read the command byte
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uint8_t cmd = Serial.read();
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// If it is 'S' (start command) then clear the serial buffer for 100ms and stop waiting
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if ( cmd == 'S' ) {
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// Precautionary receive buffer garbage flush for 50ms
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clearTime = millis() + 50;
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while ( millis() < clearTime && Serial.read() >= 0) delay(0); // Equivalent to yield() for ESP8266;
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wait = false; // No need to wait anymore
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lastCmdTime = millis(); // Set last received command time
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// Send screen size etc using a simple header with delimiters for client checks
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sendParameters(filename);
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}
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}
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else
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{
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// Check for time-out
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if ( millis() > lastCmdTime + START_TIMEOUT) return false;
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}
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}
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uint8_t color[3 * NPIXELS]; // RGB and 565 format color buffer for N pixels
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// Send all the pixels on the whole screen
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for ( uint32_t y = 0; y < tft.height(); y++)
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{
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// Increment x by NPIXELS as we send NPIXELS for every byte received
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for ( uint32_t x = 0; x < tft.width(); x += NPIXELS)
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{
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delay(0); // Equivalent to yield() for ESP8266;
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// Wait here for serial data to arrive or a time-out elapses
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while ( Serial.available() == 0 )
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{
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if ( millis() > lastCmdTime + PIXEL_TIMEOUT) return false;
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delay(0); // Equivalent to yield() for ESP8266;
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}
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// Serial data must be available to get here, read 1 byte and
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// respond with N pixels, i.e. N x 3 RGB bytes or N x 2 565 format bytes
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if ( Serial.read() == 'X' ) {
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// X command byte means abort, so clear the buffer and return
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clearTime = millis() + 50;
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while ( millis() < clearTime && Serial.read() >= 0) delay(0); // Equivalent to yield() for ESP8266;
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return false;
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}
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// Save arrival time of the read command (for later time-out check)
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lastCmdTime = millis();
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#if defined BITS_PER_PIXEL && BITS_PER_PIXEL >= 24 && NPIXELS > 1
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// Fetch N RGB pixels from x,y and put in buffer
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tft.readRectRGB(x, y, NPIXELS, 1, color);
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// Send buffer to client
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Serial.write(color, 3 * NPIXELS); // Write all pixels in the buffer
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#else
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// Fetch N 565 format pixels from x,y and put in buffer
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if (NPIXELS > 1) tft.readRect(x, y, NPIXELS, 1, (uint16_t *)color);
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else
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{
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uint16_t c = tft.readPixel(x, y);
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color[0] = c>>8;
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color[1] = c & 0xFF; // Swap bytes
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}
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// Send buffer to client
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Serial.write(color, 2 * NPIXELS); // Write all pixels in the buffer
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#endif
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}
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}
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Serial.flush(); // Make sure all pixel bytes have been despatched
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return true;
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}
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//====================================================================================
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// Send screen size etc using a simple header with delimiters for client checks
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//====================================================================================
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void sendParameters(String filename)
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{
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Serial.write('W'); // Width
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Serial.write(tft.width() >> 8);
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Serial.write(tft.width() & 0xFF);
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Serial.write('H'); // Height
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Serial.write(tft.height() >> 8);
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Serial.write(tft.height() & 0xFF);
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Serial.write('Y'); // Bits per pixel (16 or 24)
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if (NPIXELS > 1) Serial.write(BITS_PER_PIXEL);
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else Serial.write(16); // readPixel() only provides 16 bit values
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Serial.write('?'); // Filename next
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Serial.print(filename);
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Serial.write('.'); // End of filename marker
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Serial.write(FILE_EXT); // Filename extension identifier
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Serial.write(*FILE_TYPE); // First character defines file type j,b,p,t
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}
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