The breadboard/birds nest from the last post is now a shiny PCB - it just needs a box... and bit more programming. Three LEDs and a switch have been added but I haven't decided what they are for yet. Errors, probably. To recap; the Arduino controls power to the Raspberry Pi via latched relay. Once the Rpi is up the Arduino just listens for commands on the I2C bus - such as measuring Vin, or controlling the pretty lights or killing the power.The Mosfet 'drivering' the IR LED array is directly controlled by the RPi GPIO. There's a real time clock on the I2C bus too. That's about it really.
I'm working on building something similar and would love to see some more design details about how the system works together. Does the Arduino power the Pi on and off a regular intervals or do you simply have a big battery to keep the Pi running all the time?
ReplyDeleteHi Eric, I am working on writing some of this stuff up... but it's still "evolving" to some extent. i.e. I've had a few teething troubles in the field. Yes, the Arduino is doing the power management. It turns the RPi on and then waits for instructions... one of which being "turn me off until HH:MM", then I just give it a couple of minutes to shutdown.
ReplyDeleteI've been looking at sleepypi lately too though as it does most of what I need at an attractive unit cost. Even if you want to build it yourself, or build it as part of something bigger, there are some notes and schematics there that might be helpful. Jon's pi-arduino handshaking procedure is certainly more elegant than mine.
http://spellfoundry.com/products/sleepy-pi/
You could have a look at the "GertDuino" board too - I don't know much about it but it is also based on an ATMEL 328. I think it might be geared towards interfacing rather than power management.