topic Re: How to change the drive strength of MIPI-DSI output in i.MX7D in i.MX Processors

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

ko-hey — Wed, 08 Mar 2017 07:00:31 GMT

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

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

Carlos_Musich — Wed, 08 Mar 2017 13:38:34 GMT

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

ko-hey — Wed, 08 Mar 2017 23:19:01 GMT

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

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

Carlos_Musich — Wed, 15 Mar 2017 00:50:20 GMT

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

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

ko-hey — Wed, 15 Mar 2017 02:18:34 GMT

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

Ko-hey

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

Carlos_Musich — Wed, 15 Mar 2017 17:07:17 GMT

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