Use low-speed I2C as general purpose I2C

Technical Support
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1

Hi,

From Colibri iMX8X datasheet, section 5.9, it mentioned:
“Low-speed I2C without DMA support for dedicated purpose. Could also be used as general
purpose, but require the associated PHY (for example MIPI) to be powered on”

I would like to understand more on what is meant by “power on associate PHY”.
If I would like to use a low-speed I2C bus to connect to some sensors (which don’t have a PHY), and operate in 100/400KHz speed, is this possible? If yes, how should I make this happen?

Thanks.

2

Thank you so much on the input, Matthias!

enable the MIPI PHY function block of the chip via your software
May I know how can I enable it via software?
Do you means enable it via device tree? Any reference code that you could share with me?

3

May I know how can I enable it via software? Do you means enable it via device tree? Any reference code that you could share with me?

Hi @matthias.tx , do you have any advice on my questions above?

4

Thanks @andrecurvello.tx , that helps!

5

Hi @kh_ong,

There is plenty of I2C buses on the Colibri iMX8X for you to use.
One bus is already available at pins 194 (SDA) and 196 (SDL), ready to use.

You don’t need to worry about having to activate a MIPI-CSI or MIPI-DSI to use I2C.

But, if you have a curiosity about it, the way to activate MIPI on Colibri iMX8X is through the use of Device Tree Overlays. Here is an example.

Please let me know if that helped.
If not, please describe your use-cases and what you need.

Best regards,
André Curvello

6

Hi @andrecurvello , I have one follow up question.

After activated the MIPI-CSI or MIPI-DSI, may I know if the I2C will be running in standard speed (400kHz) or it will still stay as low speed?

In my application, we need more than 4 I2C buses running in standard speed.

7

Hello KH_ong,

“Power on the associate PHY” means:
That this I2c e.g. is meant to control a MIPI CSI camera therefore it is part of the MIPI Function block. You can use it for whatever you want does not have to be a camera. but to use it you need to enable the MIPI PHY function block of the chip via your software.

Best Regards,

Matthias Gohlke