ST
Library to handle the X-NUCLEO-CCA02M1 MEMS Microphones Expansion Board.
Dependencies: ST_I2S ST_FREQUENCY_DIVIDER USBDEVICE
Dependents: HelloWorld_CCA02M1 HelloWorld_CCA02M1_mbedOS HelloWorld_CCA02M1 Karaoke_CCA01M1_CCA02M1_mbedOS
Fork of
X_NUCLEO_CCA02M1
by 
ST Expansion SW Team
MEMS Microphones Library
Library to handle the X-NUCLEO-CCA02M1 MEMS Microphones Expansion Board. A single board allows to record a standard 2-channel stereo signal as an array of PCM samples (16 bit/sample); in principle, it could make use of six additional MEMS microphones to realize a 8-channel audio system.
Microphones configuration
Currently the configurations supported are the following:
- Stereo@48KHz
- Stereo@44.1KHz (CD audio quality)
- Stereo@32KHz
- Stereo@16KHz
- Stereo@8KHz
- Mono@48KHz
- Mono@44.1KHz
- Mono@32KHz
- Mono@16KHz
- Mono@8KHz
Mono configurations need a Jumper connecting PB_5 and PB_13 on the Morpho connector to properly work.
Platform compatibility
- This board can be currently used with the Nucleo F4 Family only, please see the ST_I2S library compatibility for further information.
- The library is compatible both with mbed OS 5.x and mbed classic 2.x (to work with mbed classic, the main application has to import the "events" library, which is not included into the "mbed" library).
I2S Peripheral Usage
By default this board makes use of the I2S peripheral available on Nucleo boards.
Acquiring through the USB
In order to acquire the recorded PCM audio channel with an audio SW on a PC, please connect the expansion board to a USB port of the PC, and the Nucleo board to a USB power supply.
Middlewares/OpenPDM2PCM/OpenPDMFilter.c
- Committer:
- Davidroid
- Date:
- 2018-12-12
- Revision:
- 26:53f8b511f2a1
- Parent:
- 25:f2c04f757003
File content as of revision 26:53f8b511f2a1:
/**
*******************************************************************************
* @file OpenPDMFilter.c
* @author CL
* @version V1.0.0
* @date 9-September-2015
* @brief Open PDM audio software decoding Library.
* This Library is used to decode and reconstruct the audio signal
* produced by ST MEMS microphone (MP45Dxxx, MP34Dxxx).
*******************************************************************************
* @attention
*
* <h2><center>© COPYRIGHT 2018 STMicroelectronics</center></h2>
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*******************************************************************************
*/
/* Includes ------------------------------------------------------------------*/
#include "OpenPDMFilter.h"
/* Variables -----------------------------------------------------------------*/
uint32_t div_const = 0;
int64_t sub_const = 0;
uint32_t sinc[DECIMATION_MAX * SINCN];
uint32_t sinc1[DECIMATION_MAX];
uint32_t sinc2[DECIMATION_MAX * 2];
uint32_t coef[SINCN][DECIMATION_MAX];
#ifdef USE_LUT
int32_t lut[256][DECIMATION_MAX / 8][SINCN];
#endif
/* Functions -----------------------------------------------------------------*/
#ifdef USE_LUT
int32_t filter_table_mono_64(uint8_t *data, uint8_t sincn)
{
return (int32_t)
lut[data[0]][0][sincn] +
lut[data[1]][1][sincn] +
lut[data[2]][2][sincn] +
lut[data[3]][3][sincn] +
lut[data[4]][4][sincn] +
lut[data[5]][5][sincn] +
lut[data[6]][6][sincn] +
lut[data[7]][7][sincn];
}
int32_t filter_table_stereo_64(uint8_t *data, uint8_t sincn)
{
return (int32_t)
lut[data[0]][0][sincn] +
lut[data[2]][1][sincn] +
lut[data[4]][2][sincn] +
lut[data[6]][3][sincn] +
lut[data[8]][4][sincn] +
lut[data[10]][5][sincn] +
lut[data[12]][6][sincn] +
lut[data[14]][7][sincn];
}
int32_t filter_table_mono_128(uint8_t *data, uint8_t sincn)
{
return (int32_t)
lut[data[0]][0][sincn] +
lut[data[1]][1][sincn] +
lut[data[2]][2][sincn] +
lut[data[3]][3][sincn] +
lut[data[4]][4][sincn] +
lut[data[5]][5][sincn] +
lut[data[6]][6][sincn] +
lut[data[7]][7][sincn] +
lut[data[8]][8][sincn] +
lut[data[9]][9][sincn] +
lut[data[10]][10][sincn] +
lut[data[11]][11][sincn] +
lut[data[12]][12][sincn] +
lut[data[13]][13][sincn] +
lut[data[14]][14][sincn] +
lut[data[15]][15][sincn];
}
int32_t filter_table_stereo_128(uint8_t *data, uint8_t sincn)
{
return (int32_t)
lut[data[0]][0][sincn] +
lut[data[2]][1][sincn] +
lut[data[4]][2][sincn] +
lut[data[6]][3][sincn] +
lut[data[8]][4][sincn] +
lut[data[10]][5][sincn] +
lut[data[12]][6][sincn] +
lut[data[14]][7][sincn] +
lut[data[16]][8][sincn] +
lut[data[18]][9][sincn] +
lut[data[20]][10][sincn] +
lut[data[22]][11][sincn] +
lut[data[24]][12][sincn] +
lut[data[26]][13][sincn] +
lut[data[28]][14][sincn] +
lut[data[30]][15][sincn];
}
int32_t (* filter_tables_64[2]) (uint8_t *data, uint8_t sincn) = {filter_table_mono_64, filter_table_stereo_64};
int32_t (* filter_tables_128[2]) (uint8_t *data, uint8_t sincn) = {filter_table_mono_128, filter_table_stereo_128};
#else
int32_t filter_table(uint8_t *data, uint8_t sincn, TPDMFilter_InitStruct *param)
{
uint8_t c, i;
uint16_t data_index = 0;
uint32_t *coef_p = &coef[sincn][0];
int32_t F = 0;
uint8_t decimation = param->Decimation;
uint8_t channels = param->In_MicChannels;
for (i = 0; i < decimation; i += 8) {
c = data[data_index];
F += ((c >> 7) ) * coef_p[i ] +
((c >> 6) & 0x01) * coef_p[i + 1] +
((c >> 5) & 0x01) * coef_p[i + 2] +
((c >> 4) & 0x01) * coef_p[i + 3] +
((c >> 3) & 0x01) * coef_p[i + 4] +
((c >> 2) & 0x01) * coef_p[i + 5] +
((c >> 1) & 0x01) * coef_p[i + 6] +
((c ) & 0x01) * coef_p[i + 7];
data_index += channels;
}
return F;
}
#endif
void convolve(uint32_t Signal[/* SignalLen */], unsigned short SignalLen,
uint32_t Kernel[/* KernelLen */], unsigned short KernelLen,
uint32_t Result[/* SignalLen + KernelLen - 1 */])
{
uint16_t n;
for (n = 0; n < SignalLen + KernelLen - 1; n++)
{
unsigned short kmin, kmax, k;
Result[n] = 0;
kmin = (n >= KernelLen - 1) ? n - (KernelLen - 1) : 0;
kmax = (n < SignalLen - 1) ? n : SignalLen - 1;
for (k = kmin; k <= kmax; k++) {
Result[n] += Signal[k] * Kernel[n - k];
}
}
}
void Open_PDM_Filter_Init(TPDMFilter_InitStruct *Param)
{
uint16_t i, j;
int64_t sum = 0;
uint8_t decimation = Param->Decimation;
for (i = 0; i < SINCN; i++) {
Param->Coef[i] = 0;
Param->bit[i] = 0;
}
for (i = 0; i < decimation; i++) {
sinc1[i] = 1;
}
Param->OldOut = Param->OldIn = Param->OldZ = 0;
Param->LP_ALFA = (Param->LP_HZ != 0 ? (uint16_t) (Param->LP_HZ * 256 / (Param->LP_HZ + Param->Fs / (2 * 3.14159))) : 0);
Param->HP_ALFA = (Param->HP_HZ != 0 ? (uint16_t) (Param->Fs * 256 / (2 * 3.14159 * Param->HP_HZ + Param->Fs)) : 0);
Param->FilterLen = decimation * SINCN;
sinc[0] = 0;
sinc[decimation * SINCN - 1] = 0;
convolve(sinc1, decimation, sinc1, decimation, sinc2);
convolve(sinc2, decimation * 2 - 1, sinc1, decimation, &sinc[1]);
for(j = 0; j < SINCN; j++) {
for (i = 0; i < decimation; i++) {
coef[j][i] = sinc[j * decimation + i];
sum += sinc[j * decimation + i];
}
}
sub_const = sum >> 1;
div_const = sub_const * Param->MaxVolume / 32768 / FILTER_GAIN;
div_const = (div_const == 0 ? 1 : div_const);
#ifdef USE_LUT
/* Look-Up Table. */
uint16_t c, d, s;
for (s = 0; s < SINCN; s++)
{
uint32_t *coef_p = &coef[s][0];
for (c = 0; c < 256; c++)
for (d = 0; d < decimation / 8; d++)
lut[c][d][s] = ((c >> 7) ) * coef_p[d * 8 ] +
((c >> 6) & 0x01) * coef_p[d * 8 + 1] +
((c >> 5) & 0x01) * coef_p[d * 8 + 2] +
((c >> 4) & 0x01) * coef_p[d * 8 + 3] +
((c >> 3) & 0x01) * coef_p[d * 8 + 4] +
((c >> 2) & 0x01) * coef_p[d * 8 + 5] +
((c >> 1) & 0x01) * coef_p[d * 8 + 6] +
((c ) & 0x01) * coef_p[d * 8 + 7];
}
#endif
}
void Open_PDM_Filter_64(uint8_t* data, uint16_t* dataOut, uint16_t volume, TPDMFilter_InitStruct *Param)
{
uint8_t i, data_out_index;
uint8_t channels = Param->In_MicChannels;
uint8_t data_inc = ((DECIMATION_MAX >> 4) * channels);
int64_t Z, Z0, Z1, Z2;
int64_t OldOut, OldIn, OldZ;
OldOut = Param->OldOut;
OldIn = Param->OldIn;
OldZ = Param->OldZ;
#ifdef USE_LUT
uint8_t j = channels - 1;
#endif
for (i = 0, data_out_index = 0; i < Param->Fs / 1000; i++, data_out_index += channels) {
#ifdef USE_LUT
Z0 = filter_tables_64[j](data, 0);
Z1 = filter_tables_64[j](data, 1);
Z2 = filter_tables_64[j](data, 2);
#else
Z0 = filter_table(data, 0, Param);
Z1 = filter_table(data, 1, Param);
Z2 = filter_table(data, 2, Param);
#endif
Z = Param->Coef[1] + Z2 - sub_const;
Param->Coef[1] = Param->Coef[0] + Z1;
Param->Coef[0] = Z0;
OldOut = (Param->HP_ALFA * (OldOut + Z - OldIn)) >> 8;
OldIn = Z;
OldZ = ((256 - Param->LP_ALFA) * OldZ + Param->LP_ALFA * OldOut) >> 8;
Z = OldZ * volume;
Z = RoundDiv(Z, div_const);
Z = SaturaLH(Z, -32700, 32700);
dataOut[data_out_index] = Z;
data += data_inc;
}
Param->OldOut = OldOut;
Param->OldIn = OldIn;
Param->OldZ = OldZ;
}
void Open_PDM_Filter_128(uint8_t* data, uint16_t* dataOut, uint16_t volume, TPDMFilter_InitStruct *Param)
{
uint8_t i, data_out_index;
uint8_t channels = Param->In_MicChannels;
uint8_t data_inc = ((DECIMATION_MAX >> 3) * channels);
int64_t Z, Z0, Z1, Z2;
int64_t OldOut, OldIn, OldZ;
OldOut = Param->OldOut;
OldIn = Param->OldIn;
OldZ = Param->OldZ;
#ifdef USE_LUT
uint8_t j = channels - 1;
#endif
for (i = 0, data_out_index = 0; i < Param->Fs / 1000; i++, data_out_index += channels) {
#ifdef USE_LUT
Z0 = filter_tables_128[j](data, 0);
Z1 = filter_tables_128[j](data, 1);
Z2 = filter_tables_128[j](data, 2);
#else
Z0 = filter_table(data, 0, Param);
Z1 = filter_table(data, 1, Param);
Z2 = filter_table(data, 2, Param);
#endif
Z = Param->Coef[1] + Z2 - sub_const;
Param->Coef[1] = Param->Coef[0] + Z1;
Param->Coef[0] = Z0;
OldOut = (Param->HP_ALFA * (OldOut + Z - OldIn)) >> 8;
OldIn = Z;
OldZ = ((256 - Param->LP_ALFA) * OldZ + Param->LP_ALFA * OldOut) >> 8;
Z = OldZ * volume;
Z = RoundDiv(Z, div_const);
Z = SaturaLH(Z, -32700, 32700);
dataOut[data_out_index] = Z;
data += data_inc;
}
Param->OldOut = OldOut;
Param->OldIn = OldIn;
Param->OldZ = OldZ;
}
X-NUCLEO-CCA02M1 Digital MEMS Microphones Expansion Board.