Weekly Update 7-4-16 to 7-10-16

This was a short week due to the 4th of July holiday. In addition I had to prepare and give a presentation this week for the REU program, but don’t worry I still got some good work done this week.

First off I reflowed the remaining two gyro boards, one worked and one did not. The non working one I connected to the logic analyzer and saw that the Arduino was initiating communication and the board was just not responding. I do not know what is wrong but if I find some time I will try to troubleshoot it more thoroughly.

In addition to looking at the gyro boards I finalized the design for the layered boards. The layered boards are all of the components we are using at this stage (accelerometer, gyroscope, real time clock, uSD reader, and usb LiPo charger) and consolidating them down to two boards that stack with the Arduino pro mini. I have finished the design of these boards, created a bill of materials and sent them off to be manufactured. In the process of finding the boards I did notice something odd, and that is the accelerometer I2C address does not appear correct. The I2C address is used to distinguish between the different devices connected with I2C. The accelerometer chip has a pin on it that if pulled low gives the chip one address and if pulled high gives it a second address. Currently the design for the board we are using shows this pin pulled high, but the actual address I am reading off the board is the low address. I spent awhile trying to account for this discrepancy. I ended up connecting the pin in the way the design does, however it does not matter too much since we are not using any device with a similar address. If I accidentally set the chip to the wrong address I will just change the code to reflect that.

Finally this week I began work on a board that combines the pressure and temperature sensors. This is an interesting board to design since we want it as small as possible and one part of it will be exposed to the water.