just spent a chunk of my morning wrestling with Arduino for the op amp lab, then moved to a bare metal starter project because that wasn't working, and I found myself cursing and wishing someone had just built an easy to use framework for building simple firmware for the SAM L21. then I remembered: I did that. last fall. I even wrote a hecking README. what is happening with my brain? https://github.com/joeycastillo/gossamer/
it came back to me right as I was modifying a linker file to account for the extra space occupied by the bootloader. some deeply-burrowed eight-month-old neuron raised its hand: “didn't we do this already?” then another: “yeah, and we swore we'd never do it again…”
right, yeah, that was easy. I even had the blinky test app configured for the old SAM L21 Feather; all I had to do was update the pin assignments, make and make install. can't believe I came in early to work on this.
ok so today’s tasks involve digital and analog stuff, but first I’d like to have a driver for my OLED. Alas, I can’t use the @adafruit GFX library since it’s meant for Arduino, and my gossamer framework is plain old C. So I think I’m just porting GFX to C this morning, along with their OLED driver, and at least so far this much is promising. Init sequence works and it’s full of stars.
text remains a tomorrow problem, but for the moment my little gossamer framework can render three op amps on an OLED. Now it’s time to make use of the three op amps in real life.
Simple analog accomplishment today: getting one op amp up and running. The setup is simple: I’m touching a wire, and my body is acting like an antenna. This body signal goes to OPAMP0’s positive input via a 1uF capacitor. Configured as a non-inverting amplifier with modest gain, that op amp is able to amplify the 60 Hz electrical hum in the room to a 3.3V peak-to-peak signal, which all but vanishes when I ground myself by touching my MacBook Air. I think the Feather Op Amp Lab lives!
