Microcontroller PCB for Attitude System (Thesis) - III

I've assembeled one of the 10 cards I received, which is prettty straight forward. I had some problems with a batch of LM317 voltage regulators. The pads on the component was oxidised, so I had to sand down the terminals! Better order some new ones, together with some atmega8 chips, as I'm running out fast with all these projects.

By the way, the atmega8 is nowhere near powerfull enough to do the full attitude computations. The atmega8 will do data gathering and send it to the usart port in raw ascii. Incidently, I forgot to include ground on the usart header! I guess I was thinking of the stk500/600 cards.

That's it for now. I will start looking for a programming language that supports usart under w7-64, no easy task...

Microcontroller PCB for Attitude System (Thesis) - II

The PCB that I intend to use as a prototype interface board arrived from iTeadStudio today. The quality is quite good, and for only $9.99 + shipping, this service is what I will be using from now on (except for very high tollerance stuff).

Half of the boards have been electricly tested, and are marked in red on one side.

There are a few minor issues, all of which I can live with. The main issue is that the silkscreen was converted to the same font. This caused som silkcreen to get into a few vias, and at one place it was almost completely gone. As long as I'm aware of this in the future, it's not going to be a problem.

Here is the front side of the PCB




And here is the back

New rotary encoders

Just quick update, I've recieved the new rotary encoders. These ones also sport a momentary push switch. I think I'll use that function for starting and stopping the count-down. Perhaps I'll throw in a double-tap to reset to zero. Anyway, they work well, so hopefully I'll find some time soon to finish up the electronics and programming side of the project. If I have the time tomorrow I'll shop around for some  building materials for the enclosure.

Microcontroller PCB for Attitude System (Thesis)

Didn't feel like coding yesterday, so I decided to make a uC PCB for the attitude sensor stack. I wanted to make the PCB a little more general purpose than just a PCB for interfacing with the sensors, so I've added pin-rows for all I/O-pins with annotation. Other than that, I've added header for USART, two I2C headers, a voltage regulator, and three regulated power headers. As with the other sensor PCBs, I have added 3.5mm mounting holes in the corners so that the cards can be stacked.



I'm trying out yet another PCB fabricator, iTeadStudio, which is by far the cheapest I've seen. For ten 50x50mm two-layered, green solder mask and HASL plated, it cost $14 including shipping! I also added the 'Open PCB' option, which is where they will send you two random PCBs from another order. How cool is that!

I am a little concerned that I've pushed the tolerances a bit, but we'll see when I get the PCBs. ITead specify 6mil a minimum, and recommend 8mil (0.2032 mm), but I think it should be fine.

I'll probably get the boards in a couple of weeks time, until then I will keep program using Atmels STK600 monster of a dev kit. I'll get a ICD debugging header so I don't have to lug it around with me, not to mention that horrible ZIF socket system...