audio-loopback

PDM microphone in → I²S speaker out. Demonstrates the audio capture-and-playback path from <alp/audio.h>.

Source: examples/audio-loopback/.

board.yaml

schema_version: 2

som:
  sku: E1M-AEN701

carrier:
  name: E1M-EVK

cores:
  m55_hp:
    os: zephyr
    app: ./src
    peripherals: [i2s]

diagnostics:
  log_level: info

PDM RX support (CONFIG_AUDIO_DMIC=y) lives under Zephyr's audio subsystem rather than as a standalone peripherals: entry — testcase.yaml's extra args wire it on. The application code uses the unified <alp/audio.h> surface.

Source (abbreviated)

#include <alp/audio.h>

int main(void) {
    alp_audio_in_t  *mic = alp_audio_in_open(&(alp_audio_in_config_t){
        .sample_rate_hz = 16000, .channels = 1, .bit_depth = 16,
    });
    alp_audio_out_t *spk = alp_audio_out_open(&(alp_audio_out_config_t){
        .sample_rate_hz = 16000, .channels = 1, .bit_depth = 16,
    });
    if (mic == NULL || spk == NULL) return -1;

    int16_t buf[256];
    while (1) {
        size_t got;
        alp_audio_in_read(mic, buf, ARRAY_SIZE(buf), &got);
        alp_audio_out_write(spk, buf, got);
    }
}

See also

• <alp/audio.h> reference
• i2s-tone — pure I²S output
• Examples overview