Wednesday, January 25, 2017

Accessories and peripherals time!

Part of any good system is the amount of expansion that it offers. As I'm building my own components, I can build in as much expansion as I want.

As most of my components are going to run on 1-wire or powered I2C, I chose to go with the venerable modular jack for an expansion interface - in this case, the "5222" 6P6C style connector. They're common enough that you can buy them bulk for a few dollars on the web.

Since boards are so cheap, I've laid out my own board. 6 "5222" connectors, with the capability to add both power and a DS1820 sensor (if using 1-wire systems.) Otherwise, the DS1820 can be omitted. There's some minor power filtering on the board, and the 1-oz copper should handle 800mA or so with no issues. Anything more than that would be cabled direct anyway.

The top of the board offers the I/O connectors, an LED for any power that may be supplied, and a spot for a DS1820 sensor. Currently, I'm using AVTech Room Alert devices, and this board's DS1820 sensor is wired to follow their color code. That's completely optional for other devices. There's also a pullup resistor wired into the Data/VCC lines. There's a lot of discussion on the necessity of this, but it's there. Just in case...

The bottom has the filtering for the power and the resistors for the LED and pullup. A IPC-7351\Chip-CaseC capacitor for ripple smoothing and a single 0805 for high-frequency noise reduction. All mount holes are ground plane.

The boards are shared on OSHPark, feel free to use them.

There's not a whole lot going on, but I can make these by the dozen and drop them in where needed.

5222 "6P4C" connectors. Just remember the pin numbers are different than a 6P6C!