I’ve been working on a solar panel tracker/controller as an R&D project (previous blog entries part 1 and part 2). I was able to finish the circuit board design a couple of weeks ago. I want to panelize it with some other projects so I haven’t shipped it off yet.
In the meantime I made a small change to the design. I had originally planned to use ST Micro’s new I2C/SPI accelerometer (LSM9DS0) in this design. I had previously placed an LSM9DS0 on a test board to experiment with. When that test board came in I was forced to concede that it really needs to be assembled using solder paste and an oven, versus hand soldering. That’s a bummer because I really didn’t want to take the effort to get a solder paste stencil made for this project. I decided to replace that part with the older analog output ADXL335 from Analog Devices.
While not as cool as the newer ST part, the ADXL335 has analog outputs that I routed to some ADC pins on the Microchip part I selected for this design (PIC16F1789). This will make coding the design go a little faster, which should allow me to spend more time on consulting projects that pay the bills. I also happen to be wrapping up a consulting project that uses the PIC16F1789. That part’s features will be fresh in my mind when I get a chance to start coding, making things go a little smoother.
I ‘m hoping to get this board ordered by Tuesday, and maybe set aside a few hours to write firmware later in the week. I’ll copy the serial communication protocol from some of our existing products and write some Visual Studio control software based on example programs for those same products. All of that piggy-backing might get me a prototype assembled for testing before the end of the month. Famous last words.
Below is the top copper and top solder mask layers for the PCB. This gives you an idea how some of the net routing worked out.