rt1170 MIPI DSI send dcs commands using video mode

[jreb]

Hello,
I am currently trying to address the ST7703I TFT Mobile Single Chip Driver with the rt1170 Evaluation Kit. The ST7703I only supports video mode and dcs commands must be transmitted using video mode.
In the MIPI DSI driver (https://mcuxpresso.nxp.com/api_doc/dev/2207/a00014.html ) it is described that the video mode can be started with "DSI_SetDpiConfig." After calling DSI_SetDpiConfig() are DSC commands with the function "DSI_TransferBlocking()", transferred using video mode ?

[EdwinHz]

Hi @jreb,

Yes, the necessary DCS commands are packetized and sent on video mode, as described on section "3.6 Video packetization" of i.MX 8/RT MIPI DSI/CSI-2 (nxp.com).

"Table 13. Data types" shows the DSC packets that the video mode transmissions can execute, which correspond with the ST7703_DS_v01_20160128.pdf (pine64.org), I belive.

BR,
Edwin.

[jreb]

Hi Edwin,
thanks for the answer.
In my application I have to transfer DCS Long Write (0x39) via video mode. This is not possible via the DPI-2 interface, as I can only select 16 bit (datatype 0x0E), 18 bit (datatype 0x1E), 18 bit loosely packed (datatype 0x2E) and 24 bit (datatype 0x3E) as datatypes in the PIXEL_FORMAT register (DPI_IF) of the RT1170 .

I can set the DCS datatype myself via the APB interface. The packet can be set using PKT_CONTROL register (APB_PKT_IF)  

but I can't find a way to set whether it should be transmitted via video mode or command mode.

So is it possible to transmit a DCS Long Write (0x39) via video mode?

[EdwinHz]

Hi @jreb,

Yes, it is possible.

BR,
Edwin.

[jreb]

Hi @EdwinHz 

And how can I transmit DCS Write Long (0x39) in video mode, as I don't think the registers and interfaces offer any options ?

BR
jreb

[EdwinHz]

Hi @jreb,

Please refer to our SDK example code "mipi_dsi_compliant_test_cm7" for you to see how the DCS commands are sent, especially on the API function call "MIPI_DSI_DCS_Write()" on "fsl_mipi_dsi_cmd.c".

BR,
Edwin.

[jreb · Accepted solution]

Hi @EdwinHz 

I have now got my display working. In the end it was due to an incorrect power-on initialization of the display controller. During initialization, the data and clock lanes of the ST7703I must be in LP11 (differential pairs in high level). Which can  can be achieved by setting the CFG_NONCONTINUOUS_CLK bit for CLK lanes.
As for command mode and video mode, I assume this only refers to the transmission of pixel data. So when it says that the ST7703I only supports video mode, it maybe means that it can receive commands, but the pixel data must then be transmitted in video mode.

The terms "command mode" and "video mode" may have confused me, but I'm still not 100% sure about the definition of command mode and video mode

BR

jreb

[jreb]

The block diagram of the DSI Host Controller looks like this:

My question is aimed at whether DCS commands can be transmitted via video mode via the APB interface and how I can determine whether video mode is active or not ?

Or is it possible to send DCS commands via the DPI-2 interface and how is that done ?