QUP0 i2c access on VOXL2 mini

jcai

Sort of a 2-part question:

On a VOXL2 mini, if I have both an M0155 and an M0181 on J6 and J7, is there any way to access i2c-0 on J7? I'm assuming if the coax adapter is on J7, there's no way to break out the i2c pins?

If not, then my other option is to use QUP0 on J19. I'm not running px4. Is it possible to somehow use that i2c bus from the apps proc? I've looked at libqrb5165-io and there doesn't seem to be anything for that. There's functions for accessing slpi UARTs, but only one port at a time?

Thanks

Alex Kushleyev

@jcai , can you please let me know where you see i2c0 on J7 of voxl2 mini? Please keep in mind that CCI_I2C ports are reserved for camera use.

Regarding accessing QUP0 on J19 from application processor, it not currently supported. It would require a bridge application to communicate the the DSP's I2C port. It's on our todo list to look at enabling this, but there is no timeline at this moment. The best bet right now would be writing a custom PX4 driver that will run on the DSP and talk to the device and then somehow pass that information to the application processor. There are a number of examples of i2c device drivers, such as barometer, compass drivers that are running on DSP.

Alex

jcai

@Alex-Kushleyev
https://docs.modalai.com/voxl2-mini-linux-user-guide/
https://docs.modalai.com/voxl2-mini-connectors/#j7---camera-group-1-specific-pinout
The linux user guide says that i2c0 is on J7, but the connectors page only has i2c4 on pins 34/36. Could you confirm the correct bus and pin numbers here? I'm assuming i2c4 was on an older system image, in which case are the correct pins still 34/36?

Also, turns out we're only using one camera so J7 will be free. As for QUP0, that makes sense, thanks

Alex Kushleyev

@jcai , good news. I checked the kernel Device Tree for VOXL2 Mini (M0104) and I believe that J7 has /dev/i2c-0 , which is using GPIO 4 and 5. The /dev/i2c-0 is present on on the file system.

I have not tested the i2c port just now, but you should give it a go! Just watch the digital IO voltage levels, they are 1.8V coming off from the voxl2 / mini camera connectors. Not buffered, but ESD protected.

I think we need to update the docs to reflect that this is /dev/i2c-0 and not /dev/i2c-4.

https://gitlab.com/voxl-public/system-image-build/meta-voxl2-bsp/-/blob/qrb5165-ubun1.0-14.1a/recipes-kernel/linux-msm/files/dts/m0104/m0104-modalai-qupv3.dtsi#L11

https://gitlab.com/voxl-public/system-image-build/meta-voxl2-bsp/-/blob/qrb5165-ubun1.0-14.1a/recipes-kernel/linux-msm/files/dts/common/m0xxx-kona-pinctrl.dtsi?ref_type=heads#L3117

Alex

Alex Kushleyev

BTW, you should be able to use M0076 single camera interposer or M0135 dual image interposer to access the I2C-0 pins if you need to:

https://docs.modalai.com/m0076/#2d-diagrams

TP 5 and 6 are GPIO 4 and 5

https://docs.modalai.com/m0135/

TP1 and TP2 are GPIO 4 and 5

Alex Kushleyev

https://docs.modalai.com/voxl2-mini-connectors/#j7---camera-group-1-specific-pinout has been updated to i2c-0 and SDA / SCL pins are labeled

jcai

Awesome, thanks!