nrf52832 waveshare e-paper display spi driver help

RE: nrf52832 waveshare e-paper display spi driver help

JoWi — Fri, 24 Dec 2021 16:33:38 GMT

Hi, it seems e-paper-drivers vary with with almost each production lot. finally For me "partial refresh" was important. I ended in contacting a manufacturer directly. I used displays from "good-display.com". They have a good support, but in any case: buy enough displays if you wrote the driver, because re-ordering the same model is often difficult, although bus/mechanics are same. Hence: firmware updates on the HW is indispensable. (my device: Github -> Joembedded ) Best regards, Jo

RE: nrf52832 waveshare e-paper display spi driver help

PopePepeTheFirst — Fri, 24 Dec 2021 11:34:27 GMT

In the reset function decrease delay to 2ms and run the code... I was stuck in the while loop(busy was giving me 0 in oscilloscope) and decreasing reset duration(active low) to 2 ms solved mine(basically use the same delay in example esp32 or stm code). I dont know why it happens like that..

RE: nrf52832 waveshare e-paper display spi driver help

JoWi — Tue, 07 Jan 2020 23:28:01 GMT

Hi karinca,

Did you get it work? I just now got a 2.9 B/W and a 2.13 B/W epaper (Waveshare) display too.
I tested the demo from hoeezit (from this topic), but it seems only to work with the 1.54 display.
I would be very happy make an easy test with one of my displays.

Thanks in advance, Jo

RE: nrf52832 waveshare e-paper display spi driver help

HDuc — Mon, 11 Mar 2019 17:55:52 GMT

Hi karinca,

Have you succeed to communicate the nrf52832 board with the waveshare epaper display.

RE: nrf52832 waveshare e-paper display spi driver help

hooeezit — Tue, 15 Jan 2019 05:42:24 GMT

Probably not relevant to the original poster any more, but I have a project up on Gitlab that runs a Waveshare e-paper demo on an nRF52 DK.

https://gitlab.com/hooeezit/waveshare-epaper-nrf52-dk-demo

RE: nrf52832 waveshare e-paper display spi driver help

Håkon Alseth — Wed, 01 Aug 2018 12:16:38 GMT

Documentation states that you should use SPI mode 0, which you are.

Scope your lines (especially the BUSY line) and see if you see anything out of the ordinary.

RE: nrf52832 waveshare e-paper display spi driver help

karinca — Wed, 01 Aug 2018 12:14:12 GMT

this code is from their stm32 sample, it is working perfectly on stm32f1 uc. I think they wrote a wrong definitoın on function and documentation, this works as it is. I think something's wrong with the spi communication. I ask waveshare about nrf52 code but no response.

RE: nrf52832 waveshare e-paper display spi driver help

Håkon Alseth — Wed, 01 Aug 2018 12:04:42 GMT

Hi,

The BUSY pin is an output (LOW = busy, HIGH = idle) from the e-paper, as stated in the datasheet, chapter 6: https://www.waveshare.com/w/upload/e/e6/2.9inch_e-Paper_Datasheet.pdf

Note 6-4: This pin (BUSY) is Busy state output pin. When Busy is Low the operation of chip should not be interrupted and any commands should not be issued to the module. The driver IC will put Busy pin Low when the driver IC is working such as: ...

Given the above info, it looks like this pin shall be LOW when busy, but in your firmware, you seem to be looping over it incorrectly:

/**
 *  @brief: Wait until the busy_pin goes LOW
 */
void EPD_WaitUntilIdle(EPD* epd) {
  while(EPD_DigitalRead(epd, epd->busy_pin) == HIGH) {      //0: busy, 1: idle
    EPD_DelayMs(epd, 100);
    bsp_board_led_invert(BSP_BOARD_LED_0);
  }      
}

You need to set the loop to "== LOW" to loop while it's busy.

Best regards,

Håkon