Adding Remote Logging/Connectivity to a Multimeter?  - Page 1
Forum section: electronics / beginners

author: LooseJunkHater
author_rank: Frequent Contributor
timestamp: May 21, 2025, 04:43:55 pm
content: Got the ideas from Dave's newest video, titled "EEVblog 1687 - A Pointless Alkaline Battery LEAKAGE Repair".MyHoldpeak HP770dmultimeter utilizes theHycon HY3131 chipset. Per the datasheet, it doesn't appear to have UART nor I²C, but it *does* have SPI, which I'd imagine is for communication with the built-in flash memory (which stores the progamming/config).How feasible would it be to add external interface, to pull the measurement from the multimeter, to export to a PC and used with the software shown in

author: LooseJunkHater
author_rank: Frequent Contributor
timestamp: May 21, 2025, 08:11:18 pm
content: Small update;I thought the EEProm was connecting to the HY3131, but it does not appear to. It appears that the SPI lines connect between the HY3131 (44pin) &Hycon HY11P14(100pin), which as advertised as a "8-Bit RISC-like Mixed Signal Microcontroller, Embedded 4x40 LCD Driver, Low Noise Amplifier, 18-Bit Σ∆ADC", and is clearly driving the LCD, based onthis image.I originally assumed that the HY3131 was an MCU, but it doesn't appear to be, as it's advertised as a "DMM Analog Front End", with the typical schematic of the HY3131 showing that the 4x SPI lines are used for communication with the MCU.I'd imagine I'll need to use a logic analyzer to attempt to reverse engineer the communication, and while I do have a low cost 40MHz 16-channel logic analyzer, I don't think I have the knowledge at this time in Sigrock to do this alone? Even if I did manage to reverse-engineer the SPI communication interface, how plausible is it that I'd be able to perform remote logging/connectivity?

author: abeyer
author_rank: Frequent Contributor
timestamp: May 21, 2025, 10:34:39 pm
content: It's not impossible. You shouldn't even need to reverse engineer anything, the datasheet looks to have the details you'd need. But you'd have to track the history of commands and responses and the current state of the device... and in the end would have implemented most of a meter firmware yourself to make it work.If you value your time, it would be far cheaper to buy something with connectivity. If you just want a project, I'd think it would be more interesting to start from a better device and/or build your own.

author: LooseJunkHater
author_rank: Frequent Contributor
timestamp: May 22, 2025, 04:23:52 pm
content: Quote from: abeyer on May 21, 2025, 10:34:39 pmI have essentially nil knowledge in regards to programming/MCU's, so excuse my ignorance.I'm thinking that it may be as simple as intercepting the data coming from the slave device (HY3131; MISO line) and utilize the SCLK + CS line for synchronization, right? I'll have a device intercepting all data (a separate MCU, like an STM32 or Arduino), filtering out the useful information (ex. voltage level command, and then the value of 2.5v), and then pushing that to the PC software fromhttps://lygte-info.dk?Am I dumbing this down too much? Is it unrealistic for me to accomplish this without programming/MCU experience?

author: abeyer
author_rank: Frequent Contributor
timestamp: May 22, 2025, 11:34:08 pm
content: Quote from: LooseJunkHater on May 22, 2025, 04:23:52 pmI don't think at a high-level your concept is wrong... but I think you may underestimate the complexities of implementing what you say. I would think this would be an extremely ambitious first programming project, but not fundamentally impossible given enough time and effort. For some people that kind of fast ramp up is fine, for others it just ends up frustrating them until they give up -- I'd say that's a question about yourself that only you can answer.

author: coromonadalix
author_rank: Super Contributor
timestamp: May 23, 2025, 12:58:36 am
content: the eevblog 121gw is based on the same hy3131 if i recall schematics can be foundsome github infoshttps://github.com/tpwrules/121gw-88mph/tree/master?tab=readme-ov-fileand you create a new thread instead of continuing on this one ?https://www.eevblog.com/forum/testgear/40-000-count-multimeter-under-$50-holdpeak-hp-770d/

author: ledtester
author_rank: Super Contributor
timestamp: May 23, 2025, 01:56:47 am
content: Here a data logging method that should be relatively easy to do: use a webcam to record the meter display and use OCR software to read the digits.If you search for "multimeter ocr" or "meter ocr" you'll see a lot of people have done this.For the OCR software there are a bunch of options:- ssocr --https://www.unix-ag.uni-kl.de/~auerswal/ssocr/- general purpose neural networks like Tesseract- smaller specialized NNs like what this guy used:https://github.com/prenone/MultimeterReaderHow long do you want to log data for?You might have to modify the meter to keep the backlight on and/or prevent it from powering down - but that likely can be done by just simulating button presses.

author: Terry Bites
author_rank: Super Contributor
timestamp: May 27, 2025, 05:45:56 pm
content: Why risk ruining your meter when you can make a logger for a a few euros.eghttps://thecavepearlproject.org/2014/07/01/a-10-diy-data-logger-is-born/