First look: I²CMini
Sometimes people email me. If they're having trouble with something I've made I'll try to fix it. When people write about their projects, I try to reply with encouragement. And sometimes people send product suggestions. Here's one that came in March:
To be honest some product ideas have, well, extremely limited appeal. But the more I thought about this one, the more I liked it. The turning point was when I made a quick hack for the house, and realized that what I really needed was a mini I²CDriver. So it was made.
It occurs to me that the core logic might be handy as a standalone "USB-I2C dongle" for an installation where the user has a PC or other USB host and a handful of I2C gadgets to control, but no need for the display or any debugging etc.
If one was prototyping a setup using the I2Cdriver to begin with, a faceless model would work identically and be a straightforward swap after everything is debugged.
throw it on the random feedback item pile ;)
Software-wise, it behaves exactly like I²CDriver. It has a USB mini plug (left), and a 4-pin .1 inch castellated header (bottom) that supplies clean power and the I²C signals. It lacks the screen (or course) and the voltage and current sensing of the I²CDriver.
In addition, it includes a Qwiic socket and cable. Qwiic is SparkFun's standard that uses 4-pin JST connectors to power and drive I²C peripherals.
Besides SparkFun, Smart Prototyping has an impressive range of Qwiic peripherals. Like I²CDriver, I²C mini can run as both the I²C controller and as a I²C monitor/capture device, passively listening to traffic on the Qwiic-connected I²C network.
I²CMini can also be soldered directly to a PCB. The Eagle footprint is available here, and it's the same size as all the Electric Dollar Store I²C modules, so it can be used interchangeably with them. In two minutes you can make a USB-connected RGB LED and rotary control, like this one.
I²CMini will be launching in a couple of weeks. I'll send updates in the next couple of newsletters. Thanks for reading! I hope some readers will be interested in getting their hands on one or two.
To sum up:
- Fast transfer: sustained I²C transfers at 400 and 100 kHz
- I²C pullups: programmable I²C pullup resistors, with automatic tuning
- 3.3 V output: output levels are 3.3 V, all are 5 V tolerant
- On board 300mA 3.3V voltage regulator for stable peripheral power supply
- Four-pin castellated header carrying power and I²C signals -- for pin headers or direct to PCB mounting
- High-quality 100mm Qwicc color-coded cable included
- Supports all I²C features: 7- and 10-bit I²C addressing, clock stretching, bus arbitration
- Sturdy componentry: uses an FTDI USB serial adapter, and Silicon Labs automotive-grade EFM8 controller
- Usage reporting: reports uptime, temperature, and running CRC of all traffic
- Open hardware: the design, firmware and all tools are under BSD license
- GUI, command-line, C/C++, and Python 2/3 host software provided for Windows, Mac, and Linux