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A package to communicate with the voltOTG usb volt-meter

Project description


Python class to interface with a USB volt meter named voltOTG


While surfing online I spotted a 15$ volt meter called "voltOTG" from china that connects to a smartphone, I thought it sounded fun and ordered it.

When I got it I started playing with it in the android app and saw some potential for use with for example a raspberry pi for logging voltages. So I reversed engineered the usb communications and wrote them up as a python class

How to use


Automatically connect to the voltOTG reader

import voltotg
reader = voltotg.voltOTG()

Manually connect

import voltotg
reader = voltotg.voltOTG()

Reading and printing the voltage every 10 seconds

import voltotg
from time import sleep
reader = voltotg.voltOTG()
while True:
  volts = reader.reatVolt()

Execute serial command (basic)

import voltotg
reader = voltotg.voltOTG()
command = "ReadVersion"
reply = reader.bcom(command)

Execute serial command (With empty reply fail-safe*)

import voltotg
reader = voltotg.voltOTG()
command = "ReadVersion"
reply = reader.scom(command)

Commands avaivable within voltOTG

voltOTG command serial command Explination
scom (command) N/A Executes a serial command, returns the reply, even if empty
bcom (command) N/A Executes a serial command, retries if the reply is empty. Returns the reply or error
connectDevice(devicePath) N/A Attemps to connect to a specified device
findDevice() N/A Looks for a voltOTG device by matching the VID:PID
autoConnect() N/A Runs findDevice() and uses the reply to connectDevice()
getVersion(none,list,version,name) (1) ReadVersion Returns the device version, by default it returns just the version
readVolt(none,list,voltage,info,raw) (2) ReadVolt Only returns the voltage read by the device by default
readScale(none,list,scale,calib,raw) (3) ReadScale Only returns the scale value by default
setScale(float,int) SetScale:int,float> Sets the scale value, whatever that is
readPga() ReadPga Returns the PGA, not that I have any idea what it does
setPga(1,2,4,9) SetPga:int>" Sets the PGA, which does something I assume
readMode() ReadMode Returns the mode version
setMode(0,1) SetMode:int> Sets the mode, if only I had any idea what the modes are

(1): getVersion() will return the version number, getVersion(list=True) will provide both version and name, getVersion(name=True) will return the name only, getVersion(version=True) will do the same as providing no argument

(2):readVolt() will return a voltage reading in mV, readVolt(list=True) will provide more info from the command, readVolt(raw=True) will return the raw reply from the device, readVolt(info=True) returns a weird one-off inside-the-code documentation, readVolt("voltage=True") does the same as no arguments,

(3) readScale() will return the scale value, readScale(list=True) will return a list of scale and calib, readScale(raw=True) will return the raw reply from the device, readScale(calib=True) will return the calib value, readScale(scale=True) does the same as providing no argument

Commands on device not in voltOTG

Due to me having no idea how to handle consistant data streams the first 2 commands were not implemented in the package, the last one was simply left out since I thought it was a bad idea to implement an automatic Zero-ing function, not sure if I agree with that anymore though ........

Command Explination
SetAutoSend:1> Activates a command that causes the device to send about 1 volt reading per second until it is told to stop
SetAutoSend:0> Deactivates the AutoSend feature of the device
SetZero Causes the device to take the current reading and set it as the zero point for future reads. "reader.bcom("SetZero") would run this command

Project details

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