# Voxl2 Mini i2c

Source: https://forum.modalai.com/topic/2953/voxl2-mini-i2c
Category: General Questions (https://forum.modalai.com/category/2/general-questions)
Posted: 2023-12-15 09:02:29 UTC by tiralonghipol
Replies: 8 · Views: 1908

## tiralonghipol · 2023-12-15 09:02:29 UTC

Hi,
Im testing the command i2cdetect with the magnetometer attached on J19 as swhon [here](https://docs.modalai.com/voxl2-mini-offboard-sensors/)
but I get a weird output:

```
voxl2-mini:/$ i2cdetect 0    
Warning: Can't use SMBus Quick Write command, will skip some addresses
WARNING! This program can confuse your I2C bus, cause data loss and worse!
I will probe file /dev/i2c-0.
I will probe address range 0x03-0x77.
Continue? [Y/n] y
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:                                                 
10:                                                 
20:                                                 
30: -- -- -- -- -- -- -- --                         
40:                                                 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60:                                                 
70:              
```

I tried to look it up on the web but I do not seem to find any solution for properly probe the bus. Any help?

system details:

```
system-image: 1.7.1-M0104-14.1a-perf-nightly-20231025
kernel:       #1 SMP PREEMPT Thu Oct 26 04:23:26 UTC 2023 4.19.125
--------------------------------------------------------------------------------
hw version:   M0104
--------------------------------------------------------------------------------
voxl-suite:   1.1.1
--------------------------------------------------------------------------------

```

## Reply by Eric Katzfey (ModalAI staff) · 2023-12-15 15:45:03 UTC

@tiralonghipol i2cdetect is looking on the applications processor. The i2c on J19 are routed to the DSP, not the applications processor.

## Reply by tiralonghipol · 2023-12-15 15:48:02 UTC (in reply to Eric Katzfey)

@Eric-Katzfey  thanks for your answer

so what could be a way to check if I correctly detect a i2c device on J19? assuming of course wiring is correct

## Reply by Eric Katzfey (ModalAI staff) · 2023-12-16 16:35:43 UTC (in reply to tiralonghipol)

@tiralonghipol If you run PX4 and have a supported magnetometer attached to J19 then you can see if the magnetometer driver is sending out magnetometer data. (e.g. `px4-listener sensor_mag`).

## Reply by tiralonghipol · 2023-12-17 07:36:54 UTC (in reply to Eric Katzfey)

@Eric-Katzfey  what I am trying to do is writing a driver for an external i2c imu
is there any code example where you have already implemented an i2c interface on the dsp on voxl2 mini?

## Reply by Eric Katzfey (ModalAI staff) · 2023-12-17 15:52:57 UTC (in reply to tiralonghipol)

@tiralonghipol For PX4? Then yes, take a look at some magnetometer driver code: https://github.com/modalai/px4-firmware/tree/main/src/drivers/magnetometer/isentek/ist8310

## Reply by tiralonghipol · 2023-12-18 17:10:36 UTC (in reply to Eric Katzfey)

@Eric-Katzfey amazing, thank you!

## Reply by tiralonghipol · 2024-03-06 10:53:00 UTC (in reply to Eric Katzfey)

Hei @Eric-Katzfey 

is there any code example to read the J19 i2c port 'outside' px4 ?

## Reply by Eric Katzfey (ModalAI staff) · 2024-03-07 18:29:54 UTC (in reply to tiralonghipol)

@tiralonghipol No, only within px4