Use SPIM to send data to panel, but uint8_t only send 255 byte at a time.

[Coldson]

Hi, I try to send data through SPIM to my panel(Sharp Memory LCM), and I success get the picture (only part of the picture).

The reason why is that function can only support uint8_t, max length 255 byte, but this panel need to send at least 2Kbyte at a time.

(Using function nrf_drv_spi_transfer(&spi, m_tx_buf, m_length, m_rx_buf, m_length)))

Are there any way to send 2K size data through SPI at a time?

Thx for ur kindly help.

Update 1(2016/05/14): I use nrf_drv_spi_transfer() function, send data repeatedly until all data transfer, but it's too lag to display...I will keep study it.

Update 2(2016/05/16): I decided not to use DMA and just replace all tx_buf_length with uint16_t on nrf_drv_spi.c & nrf_drv_spi.h and u can run this panel. nrf_drv_spi.c nrf_drv_spi.h

[Wojtek]

I am not 100% sure i understand ArrayList usage correctly, but i think you can use them to immediately switch to the next 255b buffer after finishing one spim transaction. you should however start each transaction explicitly, ex. manually or (better) by PPI.

[James Yu]

Yes you can do it.

1. Control the SS pin manually by configuring it as a GPIO output and and setting it high initially.
2. Break your data into 255 byte chunks
3. Before sending data set SS low.
4. Call nrf_drv_spi_transfer() for first chunk
5. Wait for SPI event handler to know when transfer is complete
6. Repeat 4-5 until all data is transferred, then set SS high.

[Coldson]

Hi, I found that SPIM EasyDMA ArraryList can handle this problem, but I don't know how to use it. Did u use that before? Thx

[James Yu]

Yes it seems that will work as well, although I haven't used it before.

[Coldson]

Hi, I try ur solution, and it work also. Thx.