AdventOfCode2025

https://adventofcode.com/2025

Build

• get session cookie from https://adventofcode.com/
• create file $HOME/.config/adventofcode.session (Linux, example: /home/alice/.config/adventofcode.session) or $HOME/Library/Application Support/adventofcode.session (macOS, example: /Users/Alice/Library/Application Support/adventofcode.session) or {FOLDERID_RoamingAppData} (Windows, example: C:\Users\Alice\AppData\Roamingadventofcode.session) and copy the cookie (esample: 53616...)
• Testing a single day:

cargo test -p dayXY

• Running a single day (release):

cargo run -p dayXY -r

• Bench a single day:

cargo bench -p dayXY

Building wasm32-unknown-unknown

cd days/dayXY/rsui && trunk build --release --filehash false --public-url /AdventOfCode2025/dayXY

Embedded

Results

Note:

• time is in milliseconds
• (*): RP PICO overclocked at 200Mhz
• (**): RP PICO2 overclocked at 290Mhz

| DAY | ESP32 | ESP32-S2 | ESP32-S3 | ESP32-C3 | ESP32-C6 | RP PICO | RP PICO (*) | RP PICO2 | RP PICO2 (**) | nRF52840 | STM32 F3 Discovery | STM32 F411E Disco | STM32 H743zi Nucleo | |----:|------:|---------:|---------:|---------:|---------:|--------:|------------:|---------:|--------------:|---------:|-------------------:|------------------:|--------------------:| | 1 | 21 | 21 | 19 | 29 | 26 | 67 | 42 | 26 | 13 | 98 | 86 | 68 | 25 | | 2 | 256 | 256 | 220 | 160 | 150 | 670 | 418 | 147 | 76 | 502 | 437 | 357 | 114 | | 3 | 154 | 150 | 152 | 173 | 150 | 441 | 275 | 109 | 56 | 346 | 312 | 272 | 133 | | 4 | 642 | 644 | 516 | 453 | 455 | 1151 | 719 | 562 | 290 | 2191 | | 1476 | 550 | | 5 | 31 | 35 | 26 | 20 | 18 | 48 | 30 | 17 | 9 | 68 | 62 | 45 | 15 | | 6 | 5 | 6 | 5 | 5 | 5 | 20 | 13 | 4 | 2 | 17 | 16 | 12 | 4 | | 7 | 7 | 8 | 6 | 7 | 7 | 19 | 11 | 10 | 5 | 44 | 35 | 30 | 7 | | 8 | | | 450 | 505 | 414 | 2489 | 1556 | 395 | 204 | 1477 | | | 364 | | 9 | 1193 | 1227 | 1025 | 1221 | 1218 | 2601 | 1625 | 1413 | 731 | 4912 | | 3177 | 1111 | | 10 | 242 | 828 | 176 | 1289 | 648 | 2046 | 1278 | 202 | 105 | 707 | | 517 | 193 | | 11 | 15 | 15 | 13 | 18 | 18 | 34 | 21 | 17 | 9 | 63 | | | 19 | | 12 | 12 | 13 | 11 | 13 | 13 | 32 | 20 | 20 | 11 | 57 | 52 | 38 | 16 |

Install probe-rs-tools

For flashing / running on rp-pico, rp-pico2, nRF52840-dk, stm32f3-discovery, stm32f4-disco and stm32h741zi-nucleo install probe-rs.

Example:

cargo binstall probe-rs-tools

Install espflash

For flashing / running on esp32, esp32s2, esp32s3, esp32c3, esp32c6 install espflash.

Example:

cargo binstall espflash

Install ravedude & toolchain for avr

For flashing / running on arduino-atmega2560 follow the instructions on this site.

Install Rust nightly

targets:

• thumbv6m-none-eabi (rp-pico)
• thumbv7em-none-eabihf (stm32 f3 discovery, stm32 h743zi nucleo, nRF 52840, ...)
• thumbv6m-none-eabi (rp-pico2)
• riscv32imc-unknown-none-elf (esp32-c3)
• riscv32imac-unknown-none-elf (esp32-c6)
• avr-none (arduino-atmega2560)

Install Rust esp32 toolkit

Install espup

targets:

• xtensa-esp32-none-elf (esp32)
• xtensa-esp32s2-none-elf (esp32-s2)
• xtensa-esp32s3-none-elf (esp32-s3)

How to invoke the MCU

1. Prepare a file like this:

START INPUT DAY: XY
<data>
END INPUT
^D

The last character is Ctrl-D (End of File).

Example data from day 1, file day01-example.txt:

START INPUT DAY: 01
L68
L30
R48
L5
R60
L55
L1
L99
R14
L82
END INPUT
^D

2. Identify the serial device. Example for linux: /dev/ttyUSB0 or /dev/ttyACM0.
3. Configure the serial device (maybe check if you need root/admin permissions). For some MCU you need a serial adapter. Example (linux):

stty -F /dev/ttyUSB0 raw 115200

4. Get data from the serial device. Example (linux):

cat /dev/ttyUSB0

5. Send the data to the serial device. Example (linux):

cat data01-example.txt > /dev/ttyUSB0

6. See the results at point 4.
7. Go to point 5 with other formatted input data for the same or other AoC day.
8. If the device does not respond in about max ten seconds probably it crashed. Check your input data. Reset the device and retry. If you have problem with your data, please create an issue.
9. Enjoy.

rp-pico

• target CPU: Cortex-M0+
• system clock: 200Mhz with feature overclock, default 125Mhz

Build for rp-pico

cargo +nightly --config target.thumbv6m-none-eabi.rustflags='["-C","target-cpu=cortex-m0plus"]' build-rp-pico

Run on rp-pico (125Mhz)

cargo +nightly --config target.thumbv6m-none-eabi.rustflags='["-C","target-cpu=cortex-m0plus"]' run-rp-pico

Run on rp-pico overclock (200Mhz)

cargo +nightly --config target.thumbv6m-none-eabi.rustflags='["-C","target-cpu=cortex-m0plus"]' run-rp-pico-overclock

rp-pico2

• target CPU: Cortex-M33
• system clock: 290Mhz with feature overclock, default 150Mhz

Build for rp-pico2

cargo +nightly --config target.thumbv8m.main-none-eabihf.rustflags='["-C","target-cpu=cortex-m33"]' build-rp-pico2

Run on rp-pico2 (150Mhz)

cargo +nightly --config target.thumbv8m.main-none-eabihf.rustflags='["-C","target-cpu=cortex-m33"]' run-rp-pico2

Run on rp-pico2 overclock (290Mhz)

cargo +nightly --config target.thumbv8m.main-none-eabihf.rustflags='["-C","target-cpu=cortex-m33"]' run-rp-pico2-overclock

stm32f3-discovery

• target CPU: Cortex-M4F
• system clock: 72Mhz

Build for stm32f3-discovery

cargo +nightly --config target.thumbv7em-none-eabihf.rustflags='["-C","target-cpu=cortex-m4"]' build-stm32f3-discovery

Run on stm32f3-discovery

cargo +nightly --config target.thumbv7em-none-eabihf.rustflags='["-C","target-cpu=cortex-m4"]' run-stm32f3-discovery

stm32f411e-disco

• target CPU: Cortex-M4F
• system clock: 96Mhz

Build for stm32f411e-disco

cargo +nightly --config target.thumbv7em-none-eabihf.rustflags='["-C","target-cpu=cortex-m4"]' build-stm32f411e-disco

Run on stm32f411e-disco

cargo +nightly --config target.thumbv7em-none-eabihf.rustflags='["-C","target-cpu=cortex-m4"]' run-stm32f411e-disco

stm32h743zi-nucleo

• target CPU: Cortex-M7F
• system clock: 400Mhz

Build for stm32h743zi-nucleo

cargo +nightly --config target.thumbv7em-none-eabihf.rustflags='["-C","target-cpu=cortex-m7"]' build-stm32h743zi-nucleo

Run on stm32h743zi-nucleo

cargo +nightly --config target.thumbv7em-none-eabihf.rustflags='["-C","target-cpu=cortex-m7"]' run-stm32h743zi-nucleo

nrf52840-dk

• target CPU: Cortex-M4F
• system clock: 64Mhz

Build for nrf52840-dk

cargo +nightly --config target.thumbv7em-none-eabihf.rustflags='["-C","target-cpu=cortex-m4"]' build-nrf52840-dk

Run on nrf52840-dk

cargo +nightly --config target.thumbv7em-none-eabihf.rustflags='["-C","target-cpu=cortex-m4"]' run-nrf52840-dk

esp32

Build for esp32

cargo +esp --config target.xtensa-esp32-none-elf.rustflags='["-C","target-cpu=esp32"]' build-esp32

Run on esp32

Serial adapter:

• TX: esp32 PIN 18 (esp32 RX out)
• RX: esp32 PIN 19 (esp32 TX out)
• GND: esp32 GND

cargo +esp --config target.xtensa-esp32-none-elf.rustflags='["-C","target-cpu=esp32"]' run-esp32

esp32s2 (mini)

Build for esp32s2 (mini)

cargo +esp --config target.xtensa-esp32s2-none-elf.rustflags='["-C","target-cpu=esp32s2"]' build-esp32s2

Run on esp32s2 (mini)

Serial adapter:

• TX: esp32s2 PIN 18 (esp32s2 RX out)
• RX: esp32s2 PIN 17 (esp32s2 TX out)
• GND: esp32s2 GND

Logging serial adapter:

• TX: esp32s2 PIN 39 (esp32s2 RX out)
• RX: esp32s2 PIN 40 (esp32s2 TX out)
• GND: esp32s2 GND
• Led at PIN 15 on when there is an error

For flashing esp32s2 (mini): hold Boot button, hold Reset button, release Reset button, release Boot button, this make the MCU on boot mode.

cargo +esp --config target.xtensa-esp32s2-none-elf.rustflags='["-C","target-cpu=esp32s2"]' run-esp32s2 -- --no-stub -b no-reset

After flashing, push Reset button for resetting.

For logging identify the second serial adapter (Logging serial adapter), example /dev/ttyUSB1, and set (maybe you need root/admin permissions):

stty -F /dev/ttyUSB1 raw 115200
cat /dev/ttyUSB1

esp32s3

Build for esp32s3

cargo +esp --config target.xtensa-esp32s3-none-elf.rustflags='["-C","target-cpu=esp32s3"]' build-esp32s3

Run on esp32s3

Serial adap