Audio I2S SDMMC nrf5340 Async

Asynchronously reads LC3 Encoded stereo audio off an SD card and plays it through the I2S audio peripheral using Embassy on an nrf5340 DK

This application is configured to run on the app core in secure mode. This means that we do not require a boot loader to unlock the peripherals we need as everything is already unlocked. There is no performance difference between secure and non-secure mode, only developer pain.

For performance reasons the mcu is set to run at 128 MHz and flash cache is enabled.

Hardware setup

nRF5340-DK development kit
UDA1334A I2S DAC (for audio)
Pins (DAC -> dk):
- 3.3v -> 3.3v
- GND -> GND
- WSEL -> P0_26
- DIN -> P0_25
- BCLK -> P0_07
Deek-Robot DK Data Logging Module - Spi SD Card reader
Pins (SD Card -> dk)
- 5v -> 3.3v (yes, this module works with 3.3v and I would NOT power it with 5v for the nrf5340's sake)
- GND -> GND
- SCL -> P1.01
- MISO -> P1.05
- MOSI -> P1.04
- CS -> P1.06

NOTE: Any SPI compatible SD Card reader should work.

Software setup

This does not run out of the box. You need a special version of probe-run that fixes the erase_all permission problem for the nrf5340 chip. You will most likely need to remove your existing version of probe-run before running the following:

cargo install --git https://github.com/knurling-rs/probe-run --branch erase-all

Also, make sure you have the correct target installed:

rustup target add thumbv8m.main-none-eabihf

Copy the zane.lc3 file to the root folder of a FAT32 formatted microSD card which goes in the sd card reader above.

Note that a forked version of the embassy library is used for i2s functionality as well as a forked version of the embedded-sdmmc-async library for async SD card reading. See Cargo.toml for more details.

To run

cargo run --release

This will use probe-run to flash the device and connect up fast RTT debug printing to the console.

Other notes

You can use the lc3-codec repo to create your own LC3 encoded files from wav files if you like. See examples section. Just make sure the filenames are no more than 8 characters long (including the extension) to play nicely with the FAT32 filesystem driver.

Credits