Other Parts Discussed in Thread: CC3200,
I am experimenting with the Audio Boosterpack together with the CC3200 Launchpad.
I used the wifi_audio_app as a basis for a first test project.
The sample project works great, altered the code a little so it will only stream audio from a microphone to a Raspberry PI.
I am now looking at how I can detect silence with the AIC3254 and only stream audio when somebody speaks in the microphone, but I have some questions on how I need to set this up.
- Is it possible to detect silence using another (simpler) method then setting up the AGC?
- I am using the following configuration based on another topic about silence detection (https://e2e.ti.com/support/data_converters/audio_converters/f/64/t/524690) to setup the AIC3254, and poll the INT1 flag (register 0x2E ) in the microphone routine, but the INT1 flag is never set?
I am using the mono connection on the Audio Boosterpack to connect the microphone.
AudioCodecPageSelect(TI3254_PAGE_0);
if(bitsPerSample == AUDIO_CODEC_16_BIT)
{
// Set I2S Mode and Word Length
AudioCodecRegWrite(0x1B, 0x00); // 0x00 16bit, I2S, BCLK is input to the device
// WCLK is input to the device,
}
else
{
return -1;
}
bitClk = bitsPerSample * bitRate * noOfChannels;
if(bitClk == 512000) // 16 kHz - 16 bits and 2 channels
{
AudioCodecPageSelect(TI3254_PAGE_0);
AudioCodecRegWrite(0x04, 0x03); // MCLK is input to PLL, PLL Clock is CODEC_CLKIN
AudioCodecRegWrite(0x05, 0x94); // PLL is powered up, P=1, R=4
AudioCodecRegWrite(0x06, 0x2A); // J=42
AudioCodecRegWrite(0x07, 0x00); // D = 0
AudioCodecRegWrite(0x0B, 0x8E); // NDAC divider powered up, NDAC = 14
AudioCodecRegWrite(0x0C, 0x81); // MDAC divider powered up, MDAC = 1
AudioCodecRegWrite(0x0D, 0x01); // DOSR = 0x0180 = 384
AudioCodecRegWrite(0x0E, 0x80); // DOSR = 0x0180 = 384
AudioCodecRegWrite(0x12, 0x95); // NADC divider powered up, NADC = 21
AudioCodecRegWrite(0x13, 0x82); // MADC divider powered up, MADC = 2
AudioCodecRegWrite(0x14, 0x80); // AOSR = 128 ((Use with PRB_R1 to PRB_R6, ADC Filter Type A)
}
else
{
return -1;
}
// Configure Power Supplies
AudioCodecPageSelect(TI3254_PAGE_1); //Select Page 1
AudioCodecRegWrite(0x01, 0x08); // Disabled weak connection of AVDD with DVDD
AudioCodecRegWrite(0x02, 0x00); // LDO Control
AudioCodecRegWrite(0x47, 0x32); // Analog inputs power up time is 6.4 ms
AudioCodecRegWrite(0x7B, 0x01); // Reference will power up in 40ms when analog blocks are powered up
// Configure INT
AudioCodecPageSelect(TI3254_PAGE_0); // Select Page 0
AudioCodecRegWrite(0x30, 0x10); // Enable AGC Threshold INT
if(mic)
{
unsigned char reg1 = 0x00; // TI3254_MICBIAS_CTRL_REG
unsigned char reg2 = 0x00; // TI3254_LEFT_MICPGA_P_CTRL_REG
unsigned char reg3 = 0x00; // TI3254_LEFT_MICPGA_N_CTRL_REG
unsigned char reg4 = 0x00; // TI3254_RIGHT_MICPGA_P_CTRL_REG
unsigned char reg5 = 0x00; // TI3254_RIGHT_MICPGA_N_CTRL_REG
unsigned char reg6 = 0x00; // TI3254_FLOAT_IP_CTRL_REG
AudioCodecPageSelect(TI3254_PAGE_8); // Select Page 8
AudioCodecRegWrite(0x01, 0x04); // Adaptive Filtering enabled for ADC
AudioCodecPageSelect(TI3254_PAGE_0); //Select Page 0
AudioCodecRegWrite(0x3D, 0x2); // ADC Signal Processing Block PRB_P2
if(mic & AUDIO_CODEC_MIC_MONO)
{
reg1 |= 0x40; // MICBIAS powered up
reg2 |= 0x00;
reg3 |= 0x10;
reg4 |= 0x10; // IN2R is routed to Right MICPGA with 10k resistance
reg5 |= 0x40; // CM is routed to Right MICPGA via CM1R with 10k resistance
reg6 |= 0x10; // IN2R input is weakly driven to common mode. Use when not routing IN2R to Left and Right MICPGA
}
AudioCodecPageSelect(TI3254_PAGE_1); //Select Page 1
AudioCodecRegWrite(0x33, reg1);
//Route IN2L not routed
AudioCodecRegWrite(0x34, reg2);
//Route IN2R CM1L to LEFT_N with 10K input impedance
AudioCodecRegWrite(0x36, reg3);
//Route IN2R to RIGHT_P with 10K input impedance
AudioCodecRegWrite(0x37, reg4);
//Route CM1R to RIGHT_M with 10K input impedance
AudioCodecRegWrite(0x39, reg5);
AudioCodecRegWrite(0x3a, reg6);
//make channel gain 0dB, since 20K input
//impedance is used single ended
AudioCodecRegWrite(0x3B, 0x00); // 0.0dB
//Unmute Right MICPGA, Gain selection of 6dB to
//make channel gain 0dB, since 20K input
//impedance is used single ended
AudioCodecRegWrite(0x3C, 0x00); // 0.0dB
//AudioCodecRegWrite(TI3254_LEFT_ADC_VOL_CTRL_REG, 0x68); // -12dB
AudioCodecRegWrite(0x54, 0x68); // -12dB
AudioCodecPageSelect(TI3254_PAGE_0); // Select Page 0
// Configure INT
AudioCodecRegWrite(0x30, 0x10); // Enable AGC Threshold INT
// Configure AGC
AudioCodecRegWrite(0x5E, 0xC2); // AGC enabled, Target level -14dB - Hysteresis +1.0dB
AudioCodecRegWrite(0x5F, 0x64); // Hysteresis 2 dB - Noise Threshold -64 dB
AudioCodecRegWrite(0x60, 0x2E); // Gain setting
AudioCodecRegWrite(0x61, 0x50); // Attack time
AudioCodecRegWrite(0x62, 0x00); // Decay time
AudioCodecRegWrite(0x63, 0x0C); // Noise Debounce time 2 * 4096 ADC words
AudioCodecRegWrite(0x64, 0x09); // Signal debounce time 1024 ADC words
//Power up LADC/RADC
AudioCodecRegWrite(0x51, 0xC0); // Left and Right Channel ADC is powered up
//Unmute LADC/RADC
AudioCodecRegWrite(0x52, 0x00); // Left and Right ADC Channel Un-muted. Left and Right ADC Channel Fine Gain = 0dB,
}
And poll function wich get called in the microphone routine.
unsigned char IsNoiseFlagSet()
{
long lRetVal = -1;
AudioCodecPageSelect(TI3254_PAGE_0); // Select Page 0
// Poll threshold flag
unsigned char ucData[2];
ucData[0] = 0;
ucData[1] = 0;
lRetVal = AudioCodecRegRead(TI3254_INT_FLAG_2_REG, &ucData[0]);
if(lRetVal < 0)
{
UART_PRINT("Unable to read Audio Code register\n\r");
MAP_UtilsDelay(3000);
}
MAP_UtilsDelay(6000);
UART_PRINT("**Register value 0x2F: %d \n\r", ucData[0]);
return (ucData[0] >> 5) & 0x01;
}
- Whats the best approach when silence is detected, can I switch off the ADC conversion? Can I still detect noise to switch it back on in this case?
Thanks in advance.
Marcel
