All,
I've been hacking on a fancier voltage display for Rob's full-throttle supercharger. It's working now on a protoboard and needs to be consolidated into a pair of project boxes, but I'm pretty pleased with how it's turning out.
I will be posting the schematics, bill of materials, and microcontroller source code on Github as soon as the git history won't make me look foolish as I remember what 2kB of RAM really means.
Features (so far):
- Shows 64 seconds of historical voltage readings as a scrolling graph
- Records temperature from two probes, one for the controller and one for the compressor
- Logs timestamp, voltage, temp1 and temp2 to a CSV file on an SD card
- Real time clock for logging to the SD card
- Drives a relay to enable system when accessory is turned on
- Daylight readable OLED display
- Display connected via standard Cat5 cable to enable remote mounting
Here's a brief video showing the display in action with a sine-function voltage source rather than the real batteries.
[ame="http://www.youtube.com/watch?v=6hH_JmlWqPI"]Phantom Full Throttle Supercharger Advanced Display, Prototype - YouTube[/ame]
The system is based right now on an
Arduino Uno (Atmega328) with Adafruit's
Logging Shield and a
Monochrome 0.96" 128x64 OLED graphic display. The temperature probes are simple
TMP36 sensors, but I have to change those to
1-wire digital probes as the TMP36s do not behave well on the required length of cable with all the EMI from the ignition system. The relay is a standard 5-30V DPDT relay I had hanging around; it's driven by a 2N3904 transistor bringing the 12V accessory to its coil.
Right now I've carved out about as much functionality as I can fit into the Atmega328; color and larger displays are possible, but are going to be difficult as there's about 300 bytes of RAM available to the stack at present, which is getting close to limits, and I'm out of EEPROM with these nice fonts.
I don't get a lot of time to work on the system, and I'm sure at least one of you will want to build one of these yourself; please be patient. I really will get all the information together; right now the Fritzing diagrams are out-of-date with what is really on the protoboard, so they need updating.
Thanks to Rob for getting me the design details and answering all my pointed questions while still handling everything else!