This week the group finished soldering components to the prototype boards and began testing the functionality of the circuits and code when running off the Pico MCU.
Starting with the Thermistor Functionality, the circuit was wired to the Pico and tested. Initially, there were issues with the code not detecting the Thermistors and displaying non-accurate values. Checking the wiring, we determined power was not being provided to the Thermistors from the MCU and corrected the wiring. After doing so, we ran the code again and confirmed that the ADC was reading values from the Thermistors. The code was modified to display the proper temperature values in from the Thermistors and each was tested against a control digital temperature sensor with which we determined the temperatures read were accurate to within approximately 2 degrees Fahrenheit of the control sensor and within approximately 1 degree of one another. A more detailed analysis of the error will be given in a future report. Below is a demonstration video.
Next, we tested the IR sensors. Firstly, it was noted that the photodiodes on two of the boards were not working as intended. The output pins of the Pico were tested and confirmed to be working. It was discovered that the connections to the photodiodes themselves were not complete, and were fixed and then tested as shown in the video below.
Secondly, there were issues present with the IR sensors related to the resistance values used for the IR Emitters and the Photo-Diodes. The input resistance for each IR Emitter was allowing them to just activate when looking at them through a digital camera but was not providing sufficient current for a strong IR emission. Conversely, the photodiodes were having trouble generating a voltage due to the 1MOhm Resistor Placed at the Cathode for reading an Avalanche Voltage generated by the photodiode. The values of the IR Emitter Resistors were swapped to a value of 47Ohms Each and the photodiode Resistor was reduced to 100kOhms. Once this was done, a test was run to confirm that the Pico code was working properly as shown in the video below.
During testing for the Battery Level Monitoring Circuit and Code, we were able to confirm that it was detecting a voltage and determining the proper number of active fans. However, there was a 200mV discrepancy in the ADC that we needed to account for. During this troubleshooting, the Raspberry Pi Pico was damaged when the positive lead of the test power supply, which was supplying 12V, hit one of the GPIO pins of the Pico, which bricked it.
A replacement Raspberry Pi Pico was ordered on 2/11/2023 and delivered on 2/12/2023 for resoldering and testing. Ian was able to detach the damaged Pico and rewire all prior connections. Testing of the Thermistors and IR sensor circuits was performed again to ensure no changes were present. All fan connections were soldered and the control circuitry is to be tested on 2/13/2023.
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