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STM32 MIPI checksums

Question asked by Eetu Piukkula on May 19, 2018
Latest reply on May 19, 2018 by Eetu Piukkula

So, I am using STM32F769xxx to run MIPI-DSI display. On the display's datasheet there are power on and off sequences. I am able to get display on and off (so commands are at least somewhat OK), but colors and data on layer are totally messed up. I have good lead on that (wrong configurations as the display normally runs on 4 lanes, MCU has only 2 lanes, I have asked manufacturer about this, they should get back to me soon), but just in case I was wondering about packet footers (checksums).

Heres visual aid:

So, here's what this looks on code:

uint8_t pSETEXTC[4] = {0xB9, 0xFF, 0x83, 0x94};
HAL_DSI_LongWrite(&hdsi, 0x00, DSI_DCS_LONG_PKT_WRITE, 4, 0x3904002C, pSETEXTC);
HAL_DSI_Refresh(&hdsi); //Is this necessary?

How is that packet footer (PF) implemented on MCU? Do I need to calculate it manually and add two bytes of data at the end of pSETEXTC or does STMs DSI-interface do it for me? I read documents but it was not too clear about this.


Thanks in advence,