FX30S Analog Input on IO 2 not reading as expected

IoT Gateways
1

I have an FX30S. I’ve used Octave to configure IO2 as an Analog input. I’ve wired the green wire from the provided cable into various voltage sources and get strange results. Here’s a quick summary of what steps I have taken:

  • Configured IO2 through Resources tab of Octave and observed measurements
  • Configured IO2 pullup to be false
  • SSHed into the FX30S using USB and directly polled the relevant ADC (/sys/devices/qpnp-vadc-8/mpp2_div1).

Here are a few sample measurements (voltage was confirmed with multimeter):

  • Voltage = 0V, Octave = 12, mpp2_div1=12000
  • Voltage = 0.75V, Octave = 139, mpp2_div1=139000
  • Voltage = 4.4V, Octave = 784, mpp2_div1=784000

My understanding is that Octave should be showing mV and the raw ADC should be in units uV. Is additional scaling needed? Or is there a configuration I’m missing to correct these bad values??

2

Hi david.drake,

This issue come from ADC scaling. Please be patient and wait for the fix on the next Octave version.

Thanks,

3

So as it stands, there is a known issue with ADC scaling of IO2. I take it the best way to deal with this is to add a correction factor of ~140?