Next Project: Car monitor, here’s a GPS breakout board

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My next project is going to be the Car monitoring circuit which logs to an SD card, as well as wirelessly broadcasts the information to my controller. The two big new things it will have are this MediaTek 3329 GPS module, and the Motion Plus Gyro.

The store that I purchased this from (for $30), wants to charge $9 for a breakout board for this, which I feel is kind of crazy (with that money, I could add an ATMEGA328 to parse the GPS), so I made a cheap $0.30 breakout board (well components push the board price to 0.50 or 1.00). It has the connections for USART and USB, and I plan to have an RJ45 connector to put this GPS circuit somewhere remote (RJ45 – ethernet connector). Thinking about disguising it in a gum box, but then again, it would be a gum box + ethernet cable coming out of it, so not much of a disguise.

I’ll update the Projects page, but here is the details of the car monitor (which will be similar to my UPC battery backup logging experiment):
– 6 Temp sensors (Engine x 2, Radiator, Transmission, outside, inside)
– GPS (location, speed, time)
– Piezo (maybe alert on high temp?)
– MotionPlus Gyro (sense direction)
– Bluetooth Serial module
– 3.3v system, powered via car battery

I will have the power for the GPS + MotionPlus + BT module controlled using a BSS123 nMOSFET, as explained here. When the car is off (can detect because Alternator pushes battery voltage to around 14.2), it will turn off the non-essential things and enter a sleep mode, where it wakes to determine if it should still sleep. Cars are noisy environments, so I will be using some techniques discussed here to protect the inputs of the ATMEGA328. This project shouldn’t take too long (ha) because most of the framework is there, I just need to add the code to sleep, to use the motionplus, filter the car battery voltage to power my circuit, and to parse the GPS data. Progress!


GPS board thoughts

I just realized that I should have breadboard-friendly pins on the GPS board, so looks like I will modify it to have those, making it a full featured board (RJ45, USB, and breadboard friendly, 2 LEDs).

I just ordered 10 6DOF accelerometers with magnetometers for a wonderful price of $5.25 each, much much better than the $30 fully assembled board that is available from Pololu and Sparkfun.  This is the next mini board that I will make as soon as finals are over. Purchased from Newark since both Mouser and Digikey have the module for more than $10.  Module is LSM303DLH, which is an ST module I believe.  These modules return 16 bit values for acceleration and magnetometer readings, which I have to determine at what level is the noise comparable to the actual signal.  It will be a little harder since I can’t exactly stick a scope on it.

It will have the following features:

  • bidirectional I2C communication (works with 5V systems!)
  • RJ45 connector
  • breadboard pins for quick prototyping
  • small form factor
  • 3V and 1.8V power supplies
  • Power LED

I try to include LED’s into my boards so that I can quickly see if its getting power.  Another idea: Enable pin to enable board, bring up voltage regulators perhaps?