Note: Work in progress, mostly for my own learning and experimentation.
A compact, simple alarm clock / time showing board built around the CH32V002 (CH32V002A4M6, RV32EmC MCU), with a multiplexed LED grid driven through a 74HC595 chain and a DS1302 RTC for timekeeping. The design includes headers for UART and I2C access, input through a linear potentiometer and push button (not onboard), a piezo buzzer as well as a speaker driver and header, that is currently not being tested, but is available on the board (PAM8302AAS).
The goal is to keep the design small (50×50mm), simple, and educational: a low-cost 2 layer RISC-V MCU board to practice PCB layout + bare-metal firmware. The final target is to be able to play MOD tracker files as an alarm sound through the speaker output, see ModPlayRISCV.
The design files are available in the /hw/ folder. The design is made in KiCad 9. Prototype boards were fabricated by PCBWay using their standard 2 layer PCB service (with matte black solder mask), while assembly was done by me.
The CH32V002 MCU is limited to 4kB of RAM and 16kB of flash, which is quite tight for a clock with alarm and sound playing capabilities. The current firmware uses 3/4rs of the flash, and a small amount of RAM, which leaves very little room left without moving to heavier space optimization. It might not be possible to fit a MOD player in the remaining space while simultaneously keeping the clock and alarm functionality...
Here are some rough current consumption measurements with the current demo:
- Running with LEDMUX demo: ~2.3 mA.
- CH32V002 in standby mode: ~500 µA. Specific measurements aren't available yet. Estimations can be made based on the datasheets and idle/quiescent current figures.
