PCB

1. Designing the baord For this week, I want to learn how to detect how close my hands are to the board, and I think it’s a perfect time to try out directly measuring capacitance with a simple circuit, where nothing is covered up by a sensor. I based the board design on Neil’s hello.load.RP2040 demo on the website (Demo), and added more header pins for hooking up a LCD next week. My plan is to tie this to my final project and make this a random spiking nervous mouse module, which will increase it’s firing probability when I get closer to it. ...

1. Preparing to mill the board With the PCB design from last week, I was ready to output it as a Gerbers file. I then convert it to .png and then invert the color of the edges layer so that the outermost edge is just the edge between black and white rather than a white line. This is now ready to be sent through the mod pipeline for milling. But then I was told that for our current settings in the shop, we can only mill single sided PCB so my original design with vials has to be re-routed. I then spent some time redesigning it, trying to avoid using a 0 ohm resistor to bridge across traces, but at last gave up and used one in the end. I would still consider this puzzle game a half-success since in the begining I would need to bridge across traces 3 or 4 times. ...

1. PCB Design with KiCAD I designed the PCB with KiCAD and imported the FAB inventory library for footprints. The design is based on previous simulation with WokWi on week 2, which uses a Xiao RP2040 to control a 16x2 LCD, displaying spikes that are randomly generated. It is also connected to a Pololu VL53L1X distance sensor. I plan to program it that when your hands move closer to the board, the spike firing probability will increase, making it like a real mice that got scared and show more neural activity when you get close. ...

1. Displaying the spikes For the output device week, I’m connecting a 20x4 I2C LCD module to my Xiao RP2040 board to display the random spikes that it’s generating. I followed this link to connect Xiao RP2040 with Thonny to program in Micropython, and uploaded two I2C LCD libraries found here onto the RP2040. Initially, I’ve stuggled a bit as it keeps saying that the SDL pin is wrong, while I’ve confiremd multiple times that it is indeed connected to the right pin. However, after closer inspection, I found out that the pin head is loose and while it’s soldered to the copper ring, the whole ring detached itself from the circuit. After a solder surgery to reconnect them it worked and now I can finally control the LCD. ...