Super simple example to push pixels to waveshare epd display
See main/main/epd_demo.c for main usage
In short: feclare an epd_t and at least set the .pins to match where you want to
wire things up. The values there now work for me.
createEpd()to set things up, this does all the esp32-specific setup, but doesnt talk to the display itself.initEpd()does a reset of the display and wait for it to be ready.
Then, each time you want to update the display:
epdBegin()gets the display into a state where it is ready to receive pixel dataepdPush()call repeatedly in a loop until exactly 600 * 448 / 2 = 134400 bytes have been transferred. If you have the whole buffer at once then this might be just once, with all the data. I like to do it line-by line to keep peak memory requirments down. Or you can push to the display as each chunk of a download completes, etc. Note: you MUST send the correct number of bytes. I have no idea what happens if you send too little or to much.epdEnd()This finialises the display, beginning the update and waiting for it to happen. Note: this may take many seconds (say, upto 30)
You can also call:
clearEpd()which, although badly named, clears the display. (it's just a fullscreen draw of while)epdSleep()puts the display to sleep. It may require anotherinitEpd()to bring back to life but I havent tested that, usually just deepsleep and effectively reboot for the next update. I get the impression from waveshare docs that it's better for the display if it is left asleep rather than init'd for long periods of time.
The buffer you push is 4-bits per pixel, packed tightly into neighbouring nybbles of a byte. So for the a 600 * 448 display we send half that many bytes.
There are 7 colours allowed. These are presented below as well as their approximate RGB values (sampled from a photo of the display, taken under non-controlled lighting conditions).
| Index | Colour | RGB | HTML |
|---|---|---|---|
| 0 | Black | ( 12, 12, 14 ) | #0c0c0e |
| 1 | White | ( 210, 210, 208 ) | #d2d2d0 |
| 2 | Green | ( 30, 96, 31 ) | #1e601f |
| 3 | Blue | ( 29, 30, 84 ) | #1d1e54 |
| 4 | Red | ( 140, 27, 29 ) | #8c1b1d |
| 5 | Yellow | ( 211, 201, 61 ) | #d3c93d |
| 6 | Orange | ( 193, 113, 42 ) | #c1712a |
Internally, epdClear() just sends 0x11 bytes to make it all white.
nice