16-bit ADC

[last updated: 2025-11-11]
-----

ADS1115

• Adafruit 1085
  This board comes in two versions: header and STEMMA QT.
  I have the "header" version, pictured.
  (link to:) Adafruit
  
• Specs:
  ADS1115
  4-channel (4@ single-ended or 2@ differential)
  16-bit ADC
  with programmable gain amplifier up to 16x gain
  I2c interface with jumper-selectable, 7-bit addresses, between 0x48-0x4B
  VCC: 2 - 5 vdc
  860 samples/sec
  The absolute maximum analog input voltage is Vin + 0.3v.
  current consumption: Continuous Mode: Only 150µA Single-Shot Mode: Auto Shut-Down
  PROGRAMMABLE DATA RATE: 8SPS to 860SPS
  INTERNAL LOW-DRIFT VOLTAGE REFERENCE
  INTERNAL OSCILLATOR
  INTERNAL PGA (programmable gain amplifier)
  PROGRAMMABLE COMPARATOR

• i2c:
  both SDA and SCL have internal 10k pullups to Vin
  Default i2c address is 0x48. 4 different addresses can be selected by connecting the ADDR pin as follows:
  ADDR-gnd = 0x48
  ADDR-Vin = 0x49
  ADDR-SDA = 0x4A
  ADDR-SCL = 0x4B

• ALRT pin:
  This is the programmable comparator output.
  -------------------------------------------------

• Programming/Operation from rPi:
  • First get i2c enabled and functioning on your rPi ,
    see: page 80...
    connect power and ground to the ADS module,
    connect ADDR pin to gnd (or wherever for the i2c address you want to use),
    connect SDA and SCL between your rPi and the ADS module
  • convoluted process. Here are the steps I did:
    sudo apt update
    sudo apt upgrade
    sudo apt install python3-pip
    sudo pip3 install --upgrade setuptools
    everything worked until this last one, that gave error: externally-managed-environment

    
    so after much googling, it seems the recommended procedure is to create a "vitrual environment":
    python -m venv my-venv (this worked...)
    my-venv/bin/pip install [some-python-library]
    so the procedure I'm following from the tutorials is trying to install: adafruit-circuitpython-ads1x15
    so I executed:
    my-venv/bin/pip install adafruit-circuitpython-ads1x15

    this worked, however gave me 3 "DEPRECATION" warnings...
    also, import board still fails...
    rebooted ... still fails

    
    trying a different apaproach: googled "i2c on rpi without using adafruit library". Following their recommentdaions...
    pip install smbus2 - failed for managed environment. crap.
    using previous procedure for installing in virtual environment:

    my-venv/bin/pip install smbus2 (note I did NOT re-create the my-venv)
    YAY! something finally worked!
    Using pipx as an alternative to pip3 if externally-managed-environment error is encountered

    sudo apt install pipx && pipx install "meshtastic[cli]"

    If using pipx it may be necessary to update $PATH by running:

    pipx ensurepath

.

.

.

eof