Raspberry Pi meets Invensense MP9150 (Thesis)

I've been playing with the Raspberry Pi for a couple of months now, and I must say it's a wonderfull piece of equipment. The ARM processor is very powerfull, and Debian is a great OS. I've been using gcc to compile my pprograms, which I have some experiemce in. The first stock Debian image didn't have I2C support, and it was quite a chore to compile the kernel. With the new Raspbian distro, I2C should be included, aswell as hardware FPU support. I've not started using it, but probably will soon.

I've managed to port my DCM code to gcc, and it's running well. I'm no longer using my sensor stack, but a development board for the new Invensense MP9150. That chip is basically an MP6150 gyro and accelerometer combo with a magnetometer on the side. I've not started using the magnetometer, but will soon. I'm currently working on a roll/pitch platform that can simulate motion. Will post more about that very soon...

LM75 based I2C temperatur sensor PCB

Again Zuken Cadstar has messed up my PCB! I'm sure there must be something I'm doing wrong, but for some reason, the ground plane copper fill that cadstar does ends up separating the plane in parts.

Anyway, apart from finally soldering together a functional board, I was eager to test it out together with my newly aquired buspirate. Not much success thought, but I think I know why: it's a problem with the address lines on the LM75; it's either a too low resistor value between the address lines and the dip switch, or the address selection through a dip switch is not a good idea.

Hardware Platform : The RaspberryPI (Thesis)

I started off looking for a hardware platform that would suit my particular needs, of which there weren't many, but from out of nowhere came the RaspberryPI. Before that I had considered several differen microcontrollers, homing in on a 32-bit microcontroller from either Atmel or Microchip. But that has all changed! I've pre-ordered my first board, and it doesn't look like this is just another piece of Vaporware: The organisation behind the board has teamed up with both RS and Farnell.

The Raspberry fulfill several criteria as a hardware platform for my thesis:
- Powerfull CPU
- Hardware FPU
- I2C
- Other low-level stuff, like GPIO, SPI, etc...
- Low(ish) power: 200-300 mA
- Small
- Cheap: 25 USD or 35 USD
- Several USARTs
- Ethernet
- Linux based (stable, secure, advanced, etc...)
- Choice of compilers: Python, C/C++, Ruby, + many more.

Can't wait to get mine. Shame my order was pushed back several weeks :(

A small PCB project, LM1307 Digital temperature sensor - Part 2

It's been a while since I've done had time for anything but my new job and my new house, hopefully I'm over the hill now, and back in bidniz.

So, not much of an update, but I've soldered the LM1307 sensor and the DIP switch onto the PCB. As I've mentioned, I'm only using 1206 discrete components, none of which have made it onto the board just yet.



I'm settling into my new workshop in my new house. It's rather messy at the moment, and I can't find anything. It's a little cold in there too, but it's brighter, bigger, and has much potential.

A small PCB project, LM1307 Digital temperature sensor

This PCB has high reuse value, I have a few projects in mind already: aquarium regulation, CCD cooling, grow house control, among a few.

I decided to use only 1206 components, as they are infinitely easier to hand solder. A smd dip switch selects functions and IO addresses.

The LM1307 also has a digital output, which I connected up to a NPN transistor, so it can drive a small load (up to a few hunded mA).

The board is quite small, and even with four 3.5mm mounting holes and rounded corners, it still measures less than 3x3 cm.