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driver/audio: mpxxdtyy: Added support for 2 microphones (stereo)

In stereo case the pdm stream continuosly alternates 1-bit from
the left channel with 1-bit from the right channel. In this case
we need first to demultiplex channels bits on byte basis.
Then the Open_PDM_Filter library has to be called twice, one for
each channel.

Signed-off-by: Armando Visconti <armando.visconti@st.com>
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avisconti authored and galak committed Mar 22, 2019
1 parent bb09c45 commit f458a50938f47b3c80022a4cf4319f3aee817623
Showing with 81 additions and 19 deletions.
  1. +1 −1 drivers/audio/mpxxdtyy-i2s.c
  2. +79 −17 drivers/audio/mpxxdtyy.c
  3. +1 −1 drivers/audio/mpxxdtyy.h
@@ -25,7 +25,7 @@ int mpxxdtyy_i2s_read(struct device *dev, u8_t stream, void **buffer,
struct mpxxdtyy_data *const data = DEV_DATA(dev);
void *pdm_block, *pcm_block;
size_t pdm_size;
TPDMFilter_InitStruct *pdm_filter = &data->pdm_filter;
TPDMFilter_InitStruct *pdm_filter = &data->pdm_filter[0];

ret = i2s_read(data->comm_master, &pdm_block, &pdm_size);
if (ret != 0) {
@@ -10,12 +10,46 @@
#include <logging/log.h>
LOG_MODULE_REGISTER(mpxxdtyy);

#define CHANNEL_MASK 0x55

static u8_t ch_demux[128] = {
0x00, 0x01, 0x00, 0x01, 0x02, 0x03, 0x02, 0x03,
0x00, 0x01, 0x00, 0x01, 0x02, 0x03, 0x02, 0x03,
0x04, 0x05, 0x04, 0x05, 0x06, 0x07, 0x06, 0x07,
0x04, 0x05, 0x04, 0x05, 0x06, 0x07, 0x06, 0x07,
0x00, 0x01, 0x00, 0x01, 0x02, 0x03, 0x02, 0x03,
0x00, 0x01, 0x00, 0x01, 0x02, 0x03, 0x02, 0x03,
0x04, 0x05, 0x04, 0x05, 0x06, 0x07, 0x06, 0x07,
0x04, 0x05, 0x04, 0x05, 0x06, 0x07, 0x06, 0x07,
0x08, 0x09, 0x08, 0x09, 0x0a, 0x0b, 0x0a, 0x0b,
0x08, 0x09, 0x08, 0x09, 0x0a, 0x0b, 0x0a, 0x0b,
0x0c, 0x0d, 0x0c, 0x0d, 0x0e, 0x0f, 0x0e, 0x0f,
0x0c, 0x0d, 0x0c, 0x0d, 0x0e, 0x0f, 0x0e, 0x0f,
0x08, 0x09, 0x08, 0x09, 0x0a, 0x0b, 0x0a, 0x0b,
0x08, 0x09, 0x08, 0x09, 0x0a, 0x0b, 0x0a, 0x0b,
0x0c, 0x0d, 0x0c, 0x0d, 0x0e, 0x0f, 0x0e, 0x0f,
0x0c, 0x0d, 0x0c, 0x0d, 0x0e, 0x0f, 0x0e, 0x0f
};

static u8_t left_channel(u8_t a, u8_t b)
{
return ch_demux[a & CHANNEL_MASK] | (ch_demux[b & CHANNEL_MASK] << 4);
}

static u8_t right_channel(u8_t a, u8_t b)
{
a >>= 1;
b >>= 1;
return ch_demux[a & CHANNEL_MASK] | (ch_demux[b & CHANNEL_MASK] << 4);
}

u16_t sw_filter_lib_init(struct device *dev, struct dmic_cfg *cfg)
{
struct mpxxdtyy_data *const data = DEV_DATA(dev);
TPDMFilter_InitStruct *pdm_filter = &data->pdm_filter;
TPDMFilter_InitStruct *pdm_filter = &data->pdm_filter[0];
u16_t factor;
u32_t audio_freq = cfg->streams->pcm_rate;
int i;

/* calculate oversampling factor based on pdm clock */
for (factor = 64U; factor <= 128U; factor += 64U) {
@@ -32,16 +66,18 @@ u16_t sw_filter_lib_init(struct device *dev, struct dmic_cfg *cfg)
return 0;
}

/* init the filter lib */
pdm_filter->LP_HZ = audio_freq / 2U;
pdm_filter->HP_HZ = 10;
pdm_filter->Fs = audio_freq;
pdm_filter->Out_MicChannels = 1;
pdm_filter->In_MicChannels = 1;
pdm_filter->Decimation = factor;
pdm_filter->MaxVolume = 64;

Open_PDM_Filter_Init(pdm_filter);
for (i = 0; i < cfg->channel.req_num_chan; i++) {
/* init the filter lib */
pdm_filter[i].LP_HZ = audio_freq / 2U;
pdm_filter[i].HP_HZ = 10;
pdm_filter[i].Fs = audio_freq;
pdm_filter[i].Out_MicChannels = cfg->channel.req_num_chan;
pdm_filter[i].In_MicChannels = cfg->channel.req_num_chan;
pdm_filter[i].Decimation = factor;
pdm_filter[i].MaxVolume = 64;

Open_PDM_Filter_Init(&data->pdm_filter[i]);
}

return factor;
}
@@ -51,23 +87,49 @@ int sw_filter_lib_run(TPDMFilter_InitStruct *pdm_filter,
size_t pdm_size, size_t pcm_size)
{
int i;
u8_t a, b;

if (pdm_block == NULL || pcm_block == NULL || pdm_filter == NULL) {
return -EINVAL;
}

for (i = 0; i < pdm_size/2; i++) {
((u16_t *)pdm_block)[i] = HTONS(((u16_t *)pdm_block)[i]);
switch (pdm_filter[0].In_MicChannels) {
case 1: /* MONO */
((u16_t *)pdm_block)[i] = HTONS(((u16_t *)pdm_block)[i]);
break;

case 2: /* STEREO */
if (pdm_filter[0].In_MicChannels > 1) {
a = ((u8_t *)pdm_block)[2*i];
b = ((u8_t *)pdm_block)[2*i + 1];

((u8_t *)pdm_block)[2*i] = left_channel(a, b);
((u8_t *)pdm_block)[2*i + 1] = right_channel(a, b);
}
break;

default:
return -EINVAL;
}
}

switch (pdm_filter->Decimation) {
switch (pdm_filter[0].Decimation) {
case 64:
Open_PDM_Filter_64((u8_t *) pdm_block, pcm_block,
pcm_size, pdm_filter);
for (i = 0; i < pdm_filter[0].In_MicChannels; i++) {
Open_PDM_Filter_64(&((u8_t *) pdm_block)[i],
&((u16_t *) pcm_block)[i],
pdm_filter->MaxVolume,
&pdm_filter[i]);
}
break;
case 128:
Open_PDM_Filter_128((u8_t *) pdm_block, pcm_block,
pcm_size, pdm_filter);
for (i = 0; i < pdm_filter[0].In_MicChannels; i++) {
Open_PDM_Filter_128(&((u8_t *) pdm_block)[i],
&((u16_t *) pcm_block)[i],
pdm_filter->MaxVolume,
&pdm_filter[i]);
}
break;
default:
return -EINVAL;
@@ -27,7 +27,7 @@ extern "C" {
struct mpxxdtyy_data {
struct device *comm_master;
enum dmic_state state;
TPDMFilter_InitStruct pdm_filter;
TPDMFilter_InitStruct pdm_filter[2];
size_t pcm_mem_size;
struct k_mem_slab *pcm_mem_slab;
};

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