Have used the sample code (Dmic) and generated the output.
the default configurations
overlay:
&clock {
hfclkaudio-frequency = <12288000>;
};
&pinctrl {
pdm0_default_alt: pdm0_default_alt {
group1 {
psels = <NRF_PSEL(PDM_CLK, 1, 12)>,
<NRF_PSEL(PDM_DIN, 1, 8)>;
};
};
};
dmic_dev: &pdm0 {
status = "okay";
pinctrl-0 = <&pdm0_default_alt>;
pinctrl-names = "default";
clock-source = "ACLK";
};
prj.conf:
CONFIG_AUDIO=y
CONFIG_AUDIO_DMIC=y
CONFIG_LOG=y
#define MAX_SAMPLE_RATE 16000
struct pcm_stream_cfg stream = {
.pcm_width = SAMPLE_BIT_WIDTH,
.mem_slab = &mem_slab,
};
struct dmic_cfg cfg = {
.io = {
/* These fields can be used to limit the PDM clock
* Configurations that the driver is allowed to use
* To those supported by the microphone.
*/
.min_pdm_clk_freq = 1000000,
.max_pdm_clk_freq = 3500000,
.min_pdm_clk_dc = 40,
.max_pdm_clk_dc = 60,
},
.streams = &stream,
.channel = {
.req_num_streams = 1,
},
};
1) how to configure PCM with sampling frequency = 2KHz ?
have changed the MAX_SAMPLE_RATE to 2000
the output observed:
*** Booting Zephyr OS build 28a3fca7da5c ***
[00:00:00.543,640] <inf> dmic_sample: DMIC sample
[00:00:00.543,670] <inf> dmic_sample: PCM output rate: 2000, channels: 1
[00:00:00.543,701] <err> dmic_nrfx_pdm: Cannot find suitable PDM clock configuration.
[00:00:00.543,701] <err> dmic_sample: Failed to configure the driver: -22
is there any way to configure PCM with sampling frequency to 2khz? and how?
2) if PCM is 2KHz. what should be the PDM clock configuration?
