How to change the drive strength of MIPI-DSI output in i.MX7D

[ko-hey]

Hi all

Are there any registers to change the drive strength of MIPI-DSI in i.MX7D ?

I'm on the compliance test of MIPI-DSI with custom board.

It failed in the section of Rise time in HS mode.

It's too slow both rise time and fall time.

So if there are registers to modify the drive strength, I want to try it.

Are there any registers to change the drive strength of MIPI-DSI in i.MX7D ?

If there are no registers to modify it, please advice me to improve the rise time.

Ko-hey

[Carlos_Musich]

Hi ko-hey,

Please see Drive Strength Field (DSE) in IOMUXC_LPSR_SW_PAD_CTL_PAD_GPIOx_IOxx register on chapter 8 IO and Pinmux
of Reference Manual http://www.nxp.com/assets/documents/data/en/reference-manuals/IMX7DRM.pdf 

Regards,
Carlos

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[ko-hey]

Hi

I think the register which you mentioned is for MUX pin such as BOOT_MODE0.

ex) DSE field of IOMUXC_LPSR_SW_PAD_CTL_PAD_BOOT_MODE0 register

I talked about following fixed pins.

MIPI_DSI_CLK_P/N

MIPI_DSI_D0_P/N

MIPI_DSI_D1_P/N

Do you have register to control the pins ?

Ko-hey

[Carlos_Musich · Accepted solution]

Hi ko-hey,

you are right, I checked and MIPI pins are dedicated to this module, so they are not multiplexed with other functionalities and they are not configurable, however our modules are compliant with the specs. You may need to check your hardware to verify why you are facing such latency.

Sorry for the inconvenience.

Regards,
Carlos

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[ko-hey]

Hi

Could you advise me which part do we check in hardware ?

Ko-hey

[Carlos_Musich]

Hi ko-hey,

If rise time and fall time are too slow most likely the problem is layout. There are some things you can verify:

- shorten distance between sensor and i.mx
- verify that the camera power source is not affecting other devices and add a bypass capacitor
- you can also check that all the wires of the camera connector are properly connected and double check any posibilty of intermittent open pins

Regards,
Carlos

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