Voxl2 analog sensor interface

tiralonghipol

Hi,
I do not see an ADC or similar pin on the Voxl2 to read an analog signal coming from a flex sensor
is there any other way to achieve this? maybe the gpio pins on J19 ?

thank you!

Moderator

@tiralonghipol Correct, there is not an ADC input on VOXL 2

tiralonghipol

@Moderator awesome!
I saw in the px4 drivers that the module i'm trying to read (ADS1115) is already supported
what I plan to do, since I am not using pin 4 and 5 on J19 (sda,scl) is to read the adc instead of the gps.

now the problem is that when I plug the ADC breakout board

and i

voxl2:/$ i2cdetect -r -y 0
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --

there is nothing on i2c-0.
actually there is no register detected on 0,1,2 (3 should not be used)

what am I doing wrong?

the physical connection is [J19 <-> adc board]:
pin 1 (5V) <-> Vin
pin 4 (SCL) <-> scl
pin 5 (SDA) <-> sda
pin 12 (GND) <-> gnd

tiralonghipol

@Moderator
Solved using the J5 connector instead!

tiralonghipol

@Moderator
so I am able to correctly read 2 flex sensors using a python library.

But is it possible to achieve the same via the px4 driver itself? if yes, where should I look into?
should I rebuild the voxl-px4 image enabling the ads1115 driver?
I believe it is disabled by default, if I understood correctly

just to give some context:
let's say the arms of my quad are able to passively flex and I read the 4 deflection angles via this ADC.
the ultimate goal I am trying to achieve is to send this analog information to the control actuator matrix and adapt it real time, taking into account the deflection

Any help is highly appreciated thanks

Eric Katzfey

@tiralonghipol That driver is not built or included in the px4 dsp build. So you would need to add that and then add it's start command to the /usr/bin/voxl-px4-start script file. You would need to specify -b 4 as an option to that start command to choose the proper bus.

tiralonghipol

@Eric-Katzfey thank you Eric!
I figured out during our time-zone difference!
I was actually able to use the pins reserved for the mag
so I built the docker, added the driver, modified the start on the correct bus but now I am unsure: where are these values published? lol

========== Starting ads1115 ADC ===========
INFO  [qshell] Send cmd: 'ads1115 start -X -b 1'
INFO  [muorb] SLPI: Marking DeviceNode(qshell_req) as advertised in process_remote_topic
INFO  [muorb] SLPI: qshell gotten: ads1115 start -X -b 1
INFO  [muorb] SLPI:   arg0 = 'ads1115'

INFO  [muorb] SLPI:   arg1 = 'start'

INFO  [muorb] SLPI:   arg2 = '-X'

INFO  [muorb] SLPI:   arg3 = '-b'

INFO  [muorb] SLPI:   arg4 = '1'

INFO  [muorb] SLPI: *** I2C Device ID 0x904809 9455625
INFO  [muorb] SLPI: ads1115 #0 on I2C bus 1
INFO  [muorb] SLPI:  (external)
INFO  [muorb] SLPI:  address 0x48
INFO  [muorb] SLPI: 

INFO  [muorb] SLPI: Ok executing command: ads1115 start -X -b 1
INFO  [qshell] qshell return value timestamp: 791748467, local time: 791750038
INFO  [uORB] Advertising remote topic sensor_baro
INFO  [qshell] Send cmd: 'sensors start'
INFO  [muorb] SLPI: Marking DeviceNode(qshell_req) as advertised in process_remote_topic
INFO  [muorb] SLPI: qshell gotten: sensors start
INFO  [muorb] SLPI:   arg0 = 'sensors'

INFO  [muorb] SLPI:   arg1 = 'start'

could be this one?

INFO  [uORB] Advertising remote topic adc_report

Eric Katzfey

@tiralonghipol I have never used that sensor but from the code it looks like adc_report is indeed the data it is publishing.