2.9" E-Ink Featherwing Display Partial Refresh Does Not Work

[chanyork]

• Arduino board: Adafruit Feather NRF52840
• E-INK: Featherwing 2.9" E-INK (Adafruit Thinkink)

The below display partial does not work. The single digits does not get updated instead only the 10th digit got updated.

'#include "Adafruit_ThinkInk.h"

#define EPD_DC 10 // can be any pin, but required!
#define EPD_CS 9 // can be any pin, but required!
#define EPD_BUSY -1 // can set to -1 to not use a pin (will wait a fixed delay)
#define SRAM_CS 6 // can set to -1 to not use a pin (uses a lot of RAM!)
#define SD_CS -4 // SD card chip select
#define EPD_RESET -1 // can set to -1 and share with chip Reset (can't deep sleep)

ThinkInk_290_Grayscale4_T5 display(EPD_DC, EPD_RESET, EPD_CS, SRAM_CS, EPD_BUSY);
//ThinkInk_154_Mono_D67 display(EPD_DC, EPD_RESET, EPD_CS, SRAM_CS, EPD_BUSY);

void setup() {
Serial.begin(115200);
// while (!Serial) { delay(10); }
// Serial.println("Adafruit counter");
display.begin(THINKINK_GRAYSCALE4);
display.setRotation(0);
}

uint16_t counter = 0;

void loop() {
display.clearBuffer();
display.setTextSize(4);
display.setTextColor(EPD_BLACK);
display.setCursor(32, 32);
display.print((counter / 1000) % 10);
display.print((counter / 100) % 10);
display.print((counter / 10) % 10);
display.print(counter % 10);

if ((counter % 10) == 0) {
display.display(false);
} else {
// redraw only 4th digit
display.displayPartial(32+(243), 32, 32+(244), 32+(4*8));
}

counter++;

}'

[ladyada]

tbh partial updates never worked very well in this librayr. you could try gxEPD or gxEPD2!