Audio Level Meter for rp2350

Overview

This is Audio Level Meter library for rp2350

This project feattures:

• Analog signal inputs for 2 channels
• Configurable dB scale steps and levels
• Preserved input attenuator values

Supported Board and Peripheral Devices

• Raspberry Pi Pico 2
• M62429 / FM62429 Electric Volume
• ST7735S 80x160 LCD

Pin Assignment

Audio Input

Pin #	Pin Name	Function	Signal Name
31	GP26	ADC0	L_IN
32	GP27	ADC1	R_IN

M62429 / FM62429 Electric Volume

Pin #	Pin Name	Function	Signal Name
19	GP14	GPIO	PIN_FM62429_DATA
20	GP15	GPIO	PIN_FM62429_CLOCK

Schematic

The frontend analog circuit should be needed.

pico_level_meter.pdf

How to build with docker image

• This project targets rp2350 (Raspberry Pi Pico 2) only
• Builds the firmware inside pico-sdk-dev-docker:sdk-2.3.0 (same image used by CI). Requires Docker; no local Pico SDK setup is needed.
• build_docker.sh drives the container build. Run it from the repository root.

$ git clone -b main https://github.com/elehobica/pico_level_meter.git
$ cd pico_level_meter
$ git submodule update -i
$ ./build_docker.sh           # build for Pico 2 (rp2350)  -> build/pico_level_meter.uf2
$ ./build_docker.sh -k        # incremental build (keep build directory contents)

• Outputs: build/pico_level_meter.uf2 for Pico 2 (rp2350)
• Download "*.uf2" on RP2350 drive

How to build in local

• This project targets rp2350 (Raspberry Pi Pico 2) only
• See "Getting started with Raspberry Pi Pico"
• Put "pico-sdk", "pico-examples" and "pico-extras" on the same level with this project folder.
• Set environmental variables for PICO_SDK_PATH, PICO_EXTRAS_PATH and PICO_EXAMPLES_PATH
• Confirmed with Pico SDK 2.3.0

> git clone -b 2.3.0 https://github.com/raspberrypi/pico-sdk.git
> cd pico-sdk
> git submodule update -i
> cd ..
> git clone -b sdk-2.3.0 https://github.com/raspberrypi/pico-examples.git
>
> git clone -b sdk-2.3.0 https://github.com/raspberrypi/pico-extras.git
> 
> git clone -b main https://github.com/elehobica/pico_level_meter.git
> cd pico_level_meter
> git submodule update -i
> cd ..

Windows

• Build is confirmed with Developer Command Prompt for VS 2022 and Visual Studio Code on Windows environment
• Confirmed with cmake-3.27.2-windows-x86_64 and gcc-arm-none-eabi-10.3-2021.10-win32
• Lanuch "Developer Command Prompt for VS 2022"

> cd pico_level_meter
> mkdir build && cd build
> cmake -G "NMake Makefiles" ..
> nmake

• Put "pico_level_meter.uf2" on RP2350 drive

Linux

• Build is confirmed with pico-sdk-dev-docker:sdk-2.3.0
• Confirmed with cmake-3.22.1 and arm-none-eabi-gcc (15:10.3-2021.07-4) 10.3.1

$ cd pico_level_meter
$ mkdir build && cd build
$ cmake ..
$ make -j4

• Download "pico_level_meter.uf2" on RP2350 drive

Serial interface usage

• type ' ' to display current settings
• type 's' to store current settings to Flash
• type '+' or '=' to decrease attenuation (level up)
• type '-' to increase attenuation (level down)
• type 'b' to adjust attenuation for both channels
• type 'l' to adjust attenuation for left channel
• type 'r' to adjust attenuation for right channel
• type 'p' to toggle peak hold mode