ID:	5103
From:	rn...@igor2.repo.hu
Date:	Sat, 4 Sep 2021 15:11:24 +0200 (CEST)
Subject:	[pcb-rnd] [electronics] minilib and utility for DMM serial proto
replies:	5104 from Majenko Technologies <ma...@majenko.co.uk> , 5105 from Doug Knabe <dk...@airmail.net>

Hi all,
 
since this list is not only about pcb-rnd but about electronics in 
general, some of you may find this useful. 
 
I had to buy a new handheld DMM and the model I got happens to have 
opto-isolated serial line and sends readouts twice a second. It's an 
UT61E, based on the ES51922 DMM chip. I looked at how others read the 
data on Linux, and found the usual sad stuff: 
 
- proprietary windows-only software, 
 
- a sigrok plugin that would require a whole sigrok installation just to 
be able to print a voltage,
 
- script implementations depending on the whole python universe and some 
"get it from github" serial line lib
 
I really prefer my software be as simple as possible, so I decided this 
needs an "-rnd solution". The chip has a detailed datasheet so the 
protocol is known. After a few hours of coding, I've released this: 
 
http://repo.hu/projects/ut61/
 
Main properties:
 
- reentrant lib for opening the port and decoding the protocol
 
- a command line utility that is very flexible on how it prints the 
decoded readout on stdout
 
- all implemented in plain C89 with no external dependencies
 
- should run on any *NIX that has the basic termios libc API for setting 
up the serial port (I normally use stty for this, but the DMM adaptor 
requires DTR and RTS set up in a specific way that is just not possible 
with stty).
 
- permissive license (LGPL)
 
- "old-style" project with author/contact info, documentation, releases
 
If you have a DMM with rs232 or USB connection and it has the same chip 
or you suspect it speaks the same protocol, give it a try!
 
Best regards,
 
Igor2

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