How to run a Window PC as I2C Master (hardware and software solution)? - Page 1
Forum section: electronics / projects

author: DigitalDesigner
author_rank: Contributor
timestamp: September 22, 2025, 04:33:57 pm
content: Hi,I’ve tested several USB-to-I²C converters, but none of them seem to do what I need them to do.What I’m trying to do is configure a PC as an I²C master, so I can send commands directly to I²C slave devices from the PC and - ideally - through something like Windows Terminal, Putty or some other similar software. Due to the urgency, spending time writing software is not an option at the moment.Does anyone have suggestions for a low-cost,ready-madesolution?Thank you

author: 0xdeadbeef
author_rank: Super Contributor
timestamp: September 22, 2025, 04:37:37 pm
content: Untested, German, most probably no the cheapest option:https://de.elv.com/p/elv-arr-bausatz-usb-ic-interface-usb-i2c-2-P160452

author: tomeko
author_rank: Newbie
timestamp: September 22, 2025, 07:10:01 pm
content: Do you have CH341-based serial memory programmer or generic CH341 board?I have writtenhttps://tomeko.net/software/CH341A_tool/but it is more GUI than terminal-oriented.If you need terminal, maybe something like Bus Pirate or one of its clones would be what you are looking for.

author: tooki
author_rank: Super Contributor
timestamp: September 22, 2025, 07:23:42 pm
content: Quote from: DigitalDesigner on September 22, 2025, 04:33:57 pmWhat I have used extensively is the Aardvark:https://www.totalphase.com/products/aardvark-i2cspi/I think it's quite overpriced for what it is, but I can say that it does work as promised. I used it heavily at my old job while developing a device with a bunch of I2C peripherals.I've been looking for a cheaper alternative to buy for myself, but so far without much luck.I've tried the MCP2221A boards, which are cheap as chips, but the sample software from Microchip is not great.There's the Bus Pirate and the like; I've never used them.The CH341 app tomeko wrote looks really cool. I'll have to try it out.

author: tooki
author_rank: Super Contributor
timestamp: September 22, 2025, 07:25:59 pm
content: Quote from: tomeko on September 22, 2025, 07:10:01 pmThat looks awesome.Am I interpreting correctly that the GUIs for specific peripherals are hard-coded into the app itself? Or is there some way for a user to create a GUI for a particular device on their own?

author: tomeko
author_rank: Newbie
timestamp: September 22, 2025, 07:31:45 pm
content: Quote from: tooki on September 22, 2025, 07:25:59 pmUnfortunately yes as I'm not anticipating anyone would be interested in creating any sort of plugins for it. Required effort would be virtually identical to using CH341 dll directly and I think everyone has own favorite way of making GUI applications.Side note, CH341 is cheap and popular, should work with most of the things, but has few quirks: limited I2C speed range (some I2C sensors like AGS10 TVOC require I2C speed below 15 kHz), only one API function checks for ACK (at least according to my knowledge), I2C clock stretching is not handled. I think CH347 might be improved, but I have not tested it. Another very cheap adapter is CP2112 (I have bought one, but not tested so far).

author: voltsandjolts
author_rank: Unknown
timestamp: September 22, 2025, 08:02:40 pm
content: If you like python then pyftdi.https://eblot.github.io/pyftdi/api/i2c.htmlhttps://www.eevblog.com/forum/microcontrollers/need-getting-started-example(s)-using-pyftdi-to-access-gpio-and-i2c-on-ft232h/

author: thm_w
author_rank: Super Contributor
timestamp: September 22, 2025, 09:55:36 pm
content: https://www.crowdsupply.com/excamera/i2cdriver

author: Zoli
author_rank: Frequent Contributor
timestamp: September 23, 2025, 06:20:48 am
content: In addition to the previous post:https://i2cdriver.com/mini.html

author: Smokey
author_rank: Super Contributor
timestamp: September 23, 2025, 08:04:16 am
content: https://en.wikipedia.org/wiki/Bus_Piratehttps://buspirate.com/https://www.adafruit.com/product/6017https://www.digikey.com/en/products/detail/sparkfun-electronics/12942/5994960?gad_campaignid=20243136172etc.

author: fdgb
author_rank: Newbie
timestamp: September 24, 2025, 05:52:08 am
content: you could try the FT232H or FT2232H modules — they can act as I²C masters and are pretty easy to control from a PC using command line tools. BusPirate is another inexpensive tool that works well for quick testing and sending commands without writing custom code.

author: DigitalDesigner
author_rank: Contributor
timestamp: September 25, 2025, 03:06:22 am
content: Thank you all!Much appreciated solutions and suggestions!

author: croma641
author_rank: Regular Contributor
timestamp: September 25, 2025, 03:33:53 am
content: There's another version of the Bus Pirate—multi-protocol, ultra-cheap, freshly "baked" by the author. It uses an ESP32 Devkit. Around €6. Fantastic.-https://github.com/geo-tp/ESP32-Bus-Pirate-