2020-08-07 (F) Weekly Summary

After you carry a custom box in your pocket, with its sharp corners and awkward shape, you note what needs improvement. I haven't gotten to the sharp edges yet, but I made a hole for the USB port and deeper grooves for my components to sit.
Base model

I asked some other hackers what they would like to see in this project, and the response was sluggish. I feared that sharing my $70USD price tag scared some folks away, so I decided to start an inexpensive spin-off. Instead of the Adafruit parts, I bought Chinese modules. The IMU was still $10, but the total price tag, not including a power pack, should be under $20. The device will not include Bluetooth, and I will call it miniCard, for miniature Cardinal.

Parts for miniCard

I assembled my knock-off Arduino, Chinese IMU module, and a vibrating motor. I kept the boards separate with header pins that connected my I2C channel. I should have installed the programming port pins first because the IMU board overlapped, but I got it sorted out. The vibrating motor was under the microcontroller board.

MCU and IMU

I have purchased a few USB↔serial converters, and sometimes they contain counterfeit chips and refuse to work. My computer recognized this one, but the pins were not in the order I expected, so I had to map out the wires. I was able to program the BLINK example. My next step was to migrate my old Cardinal code to this controller. I had to solder some connections on the IMU, and then I could connect, but my program still needed a few tweaks.
Mapped cable functions

I revised my miniCard code to recognize the IMU and function like it was supposed to do. I added a micro USB port for power and repurposed the RESET switch one of the input pins. Unfortunately, I ran into an issue where if I used the digitalRead() in my code, it would lock up the processor. I need to figure this out.
MiniCard top and bottom

I had a couple of ways to get around the issue with digitalRead(), and the first was to add a jumper wire to one of the analog pins because analogRead() worked correctly. After I proved this worked, I researched how to read a digital input with some low-level programming and came up with "((PINB >> 3) % 2)" instead of digitalRead(11). Both solutions worked, and I proceeded to add code to zero out the heading after I pressed the button.

Working heading button and unnecessary wire

The rest of the summary posts have been arranged by date.
First time here?

Completed projects from year 1
Completed projects from year 2
Completed projects from year 3
Completed projects from year 4
Completed projects from year 5
Completed projects from year 6
Completed projects from year 7

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