Bug Filed on 06-13-2016: ADS1115 default settings and wrong volts


#1

What dashboard are you using? (Web, iOS, Android)
iOS, Android, web


What OS? (Jessie, Wheezy)
Jessie


What Model Pi?
3


Please describe the bug / issue. Attaching any relevant screenshots would be very helpful!

First, the settings issue:
Is there a way to set the sample rate, mode, gain on the ADS1115?

The incorrect volts issue:
I recently installed an ADS1115 analog to digital converter on my Pi.

Extension ADS1115 may be stuck in one shot mode, if not, an erratic switch exists between zero and ‘correct’ values.

The second and fourth inputs to the ADS1115 appear switch compared to Adafruit specs.

I’m using +5vdc for VDD.
I have 3.3vdc on ‘ai1’ and Cayenne seems to have that input assigned to ai3, (ai0, ai1, ai2, ai3).

The behavior is difficult to describe.
The continuous fluctuation is readily visible on Weaved/WebIOPi’s Devices Monitor example app or on either phone type.
The adc on the web and both phone types, fluctuates, except for timing, identically on all devices.
The correct reading for 2-3 seconds (albeit on the wrong pin) then zero for 2-20 seconds.
The slider on the phones sometimes moves without a numerical readout.
The slider sometimes lags the readout. Phone types are loosely synchronized.
The Cayenne webpage misses most of the ‘correct’ reads the phones get.
The Weaved/WebIOPi/Devices Monitor example pc webpage more closely tracks the phones’ activity.

I’ve used four measures:
Cayenne pc webpage
Weaved/WebIOPi example - ‘Devices Monitor’ pc webpage
iPhone Cayenne app
iPhone Weaved app (lags a little behind the pc webpage)
Android Cayenne app

The wiring list follows:
RPi-ADS1115 wiring scheme

VDD - RED - 4 (5VDC)
GND - BLACK - (GND)
SCL- BROWN - 5 (SCL1)
SDA - PURPLE - 3 (SDA1)
ADDR - GRAY - 14 (GND)
ALRT - FLOAT
Ai0 - BLUE - 34 (GND)
Ai1 - GREEN - 1 (3.3VDC)
Ai2 - YELLOW - 30 (GND)
Ai3 - ORANGE - 25 (GND)

ADDR PIN - SLAVE ADDRESS
Gnd - 1001000 (0x48)
VDD - 1001001 (0x49)
SDA - 1001010 (0x4A)
SCL - 1001011 (0x4B)

Update:
I deleted everything and started from scratch. Most important; I removed edits to webiopi’s config file. Now I get the same 0.27 reading on all channels, steadily.

Thank you
Jim J


#2

Hi @jimlynnjulian2,

Cayenne uses a modified version of WebIOPi, so we recommend using Cayenne with no previous versions of WebIOPi installed. I’m guessing this was the issue you were having with the ADS1115 sensor. Thanks for updating us on this.

I’ll move this post to resolved now :slight_smile:

-B


#3

Hello,

I considered the possibility.
Who owns the webiopi service that boots on my Pi? I can remove the service from the boot list. If that works, I’ll take that route.
If not, I’ll delete the webiopi directory and reinstall Cayenne.
If I get the ADS1115 running and other anomies disappear, I’m done, if not I’ll repost the issue.
You spund certain so I have high expectations.

Thank you,