Plays USB Audio packets through external DAC (Cirrus Logic CS4344). Simple demo code, don't expect a sophisticated I2S library. HW setup: mbed DIP 5 (I2STX_SDA) -> DAC SDIN (Serial Audio Data Input) mbed DIP 6 (I2STX_WS) -> DAC LRCK (Left Right Clock) mbed DIP 7 (I2STX_CLK) -> DAC SCLK (External Serial Clock Input) mbed DIP 30 (I2SRX_CLK) -> DAC MCLK (Master Clock) also needed an extra USB connector wired to mbed. Does not work with built-in USB. Code needs a bit of clean up.
I2S.cpp@1:12e8ee1b7ea2, 2012-04-16 (annotated)
- Committer:
- csorbag
- Date:
- Mon Apr 16 08:32:38 2012 +0000
- Revision:
- 1:12e8ee1b7ea2
- Parent:
- 0:bf9e7b99dda5
Who changed what in which revision?
User | Revision | Line number | New contents of line |
---|---|---|---|
csorbag | 0:bf9e7b99dda5 | 1 | #include "I2S.h" |
csorbag | 0:bf9e7b99dda5 | 2 | #include "MODDMA.h" |
csorbag | 0:bf9e7b99dda5 | 3 | |
csorbag | 0:bf9e7b99dda5 | 4 | |
csorbag | 0:bf9e7b99dda5 | 5 | volatile uint32_t counter=0; |
csorbag | 0:bf9e7b99dda5 | 6 | |
csorbag | 0:bf9e7b99dda5 | 7 | DigitalOut led3(LED3); |
csorbag | 0:bf9e7b99dda5 | 8 | |
csorbag | 0:bf9e7b99dda5 | 9 | //Serial *global_out; |
csorbag | 0:bf9e7b99dda5 | 10 | MODDMA dma; |
csorbag | 0:bf9e7b99dda5 | 11 | MODDMA_Config *dmaconfig; |
csorbag | 0:bf9e7b99dda5 | 12 | |
csorbag | 0:bf9e7b99dda5 | 13 | void TC0_callback(void); |
csorbag | 0:bf9e7b99dda5 | 14 | void TC1_callback(void); |
csorbag | 0:bf9e7b99dda5 | 15 | void TC2_callback(void); |
csorbag | 0:bf9e7b99dda5 | 16 | |
csorbag | 0:bf9e7b99dda5 | 17 | #define BUFFER_SIZE 2048 |
csorbag | 0:bf9e7b99dda5 | 18 | |
csorbag | 0:bf9e7b99dda5 | 19 | int16_t buffer[BUFFER_SIZE]; |
csorbag | 0:bf9e7b99dda5 | 20 | |
csorbag | 0:bf9e7b99dda5 | 21 | int16_t transferSize; |
csorbag | 0:bf9e7b99dda5 | 22 | |
csorbag | 0:bf9e7b99dda5 | 23 | int16_t *bufferStart, *nextToPlay; |
csorbag | 0:bf9e7b99dda5 | 24 | volatile int16_t playing = 0; |
csorbag | 0:bf9e7b99dda5 | 25 | |
csorbag | 0:bf9e7b99dda5 | 26 | volatile int16_t moreToPlay=0; |
csorbag | 0:bf9e7b99dda5 | 27 | |
csorbag | 0:bf9e7b99dda5 | 28 | void setup(Serial *out) { |
csorbag | 0:bf9e7b99dda5 | 29 | |
csorbag | 0:bf9e7b99dda5 | 30 | global_out = out; |
csorbag | 0:bf9e7b99dda5 | 31 | |
csorbag | 0:bf9e7b99dda5 | 32 | bufferStart = nextToPlay = (int16_t *)buffer; |
csorbag | 0:bf9e7b99dda5 | 33 | |
csorbag | 0:bf9e7b99dda5 | 34 | LPC_SC->PCONP |= 1 <<27; // Enable I2S |
csorbag | 0:bf9e7b99dda5 | 35 | LPC_SC->PCLKSEL1 |= 1 << 22; // Set Clock to CCLK |
csorbag | 0:bf9e7b99dda5 | 36 | // Reset i2s |
csorbag | 0:bf9e7b99dda5 | 37 | LPC_I2S->I2SDAO = (1 << 4); |
csorbag | 0:bf9e7b99dda5 | 38 | LPC_I2S->I2SDAO = 0; |
csorbag | 0:bf9e7b99dda5 | 39 | |
csorbag | 0:bf9e7b99dda5 | 40 | |
csorbag | 0:bf9e7b99dda5 | 41 | |
csorbag | 0:bf9e7b99dda5 | 42 | LPC_I2S->I2SDAO = 1 /* Number of bytes 16bit */ | 0xF << 6 /* Word select half perion - 1 */;// | 1 << 3 /* Stop bit */; |
csorbag | 0:bf9e7b99dda5 | 43 | LPC_I2S->I2SDAI = 1 /* Number of bytes 16bit */ | 0xF << 6 /* Word select half perion - 1 */;// | 1 << 3 /* Stop bit */; |
csorbag | 0:bf9e7b99dda5 | 44 | |
csorbag | 0:bf9e7b99dda5 | 45 | |
csorbag | 0:bf9e7b99dda5 | 46 | LPC_PINCON->PINSEL0 |= 01 << 14 /* I2STX_CLK */ | 01 << 16 /* I2STX_WS */ | 01 << 18 /* I2STX_SDA */; |
csorbag | 0:bf9e7b99dda5 | 47 | LPC_PINCON->PINSEL0 |= 01 << 8 /* I2SRX_CLK */ | 01 << 10 /* I2SRX_WS */ | 01 << 12 /* I2SRX_SDA */; |
csorbag | 0:bf9e7b99dda5 | 48 | |
csorbag | 0:bf9e7b99dda5 | 49 | // Set all to neither pull-up, nor pull-down |
csorbag | 0:bf9e7b99dda5 | 50 | LPC_PINCON->PINMODE0 |= 2 << 14 /* I2STX_CLK */ | 2 << 16 /* I2STX_WS */ | 2 << 18 /* I2STX_SDA */; |
csorbag | 0:bf9e7b99dda5 | 51 | LPC_PINCON->PINMODE0 |= 2 << 8 /* I2SRX_CLK */ | 2 << 10 /* I2SRX_WS */ | 2 << 12 /* I2SRX_SDA */; |
csorbag | 0:bf9e7b99dda5 | 52 | |
csorbag | 0:bf9e7b99dda5 | 53 | |
csorbag | 0:bf9e7b99dda5 | 54 | // Cirrus Logic CS4344 specific frequency settings |
csorbag | 0:bf9e7b99dda5 | 55 | LPC_I2S->I2STXRATE = 125 /* Y_divider */ | 4 << 8 /* X_divider */; |
csorbag | 0:bf9e7b99dda5 | 56 | LPC_I2S->I2SRXRATE = 125 /* Y_divider */ | 32 << 8 /* X_divider */; |
csorbag | 0:bf9e7b99dda5 | 57 | |
csorbag | 0:bf9e7b99dda5 | 58 | int rxbitrate = 1; |
csorbag | 0:bf9e7b99dda5 | 59 | LPC_I2S->I2STXBITRATE = 1; |
csorbag | 0:bf9e7b99dda5 | 60 | LPC_I2S->I2SRXBITRATE = rxbitrate; |
csorbag | 0:bf9e7b99dda5 | 61 | |
csorbag | 0:bf9e7b99dda5 | 62 | |
csorbag | 0:bf9e7b99dda5 | 63 | LPC_I2S->I2STXMODE = (0 << 0) | (1 << 3); |
csorbag | 0:bf9e7b99dda5 | 64 | LPC_I2S->I2SRXMODE = (0 << 0) | (1 << 3); |
csorbag | 0:bf9e7b99dda5 | 65 | |
csorbag | 0:bf9e7b99dda5 | 66 | |
csorbag | 0:bf9e7b99dda5 | 67 | // Start trasnmit |
csorbag | 0:bf9e7b99dda5 | 68 | LPC_I2S->I2SDAO &= (~(1 << 3)); |
csorbag | 0:bf9e7b99dda5 | 69 | LPC_I2S->I2SDAI &= (~(1 << 3)); |
csorbag | 0:bf9e7b99dda5 | 70 | |
csorbag | 0:bf9e7b99dda5 | 71 | LPC_I2S->I2SDMA1 = (1 << 1) /* Enable transit */ | (0 << 16) /* Transmit FIFO level */; |
csorbag | 0:bf9e7b99dda5 | 72 | |
csorbag | 0:bf9e7b99dda5 | 73 | |
csorbag | 0:bf9e7b99dda5 | 74 | out->printf("I2S Setup complete\n"); |
csorbag | 0:bf9e7b99dda5 | 75 | |
csorbag | 0:bf9e7b99dda5 | 76 | dmaconfig = new MODDMA_Config; |
csorbag | 0:bf9e7b99dda5 | 77 | dmaconfig |
csorbag | 0:bf9e7b99dda5 | 78 | ->channelNum ( MODDMA::Channel_0 ) |
csorbag | 0:bf9e7b99dda5 | 79 | // ->srcMemAddr ( (uint32_t) &buffer1 ) |
csorbag | 0:bf9e7b99dda5 | 80 | ->dstMemAddr ( 0 ) |
csorbag | 0:bf9e7b99dda5 | 81 | //->transferSize ( 2500 ) |
csorbag | 0:bf9e7b99dda5 | 82 | ->transferType ( MODDMA::m2p ) |
csorbag | 0:bf9e7b99dda5 | 83 | ->transferWidth ( 1 ) |
csorbag | 0:bf9e7b99dda5 | 84 | ->srcConn ( 0 ) |
csorbag | 0:bf9e7b99dda5 | 85 | ->dstConn ( MODDMA::I2S_Channel_0 ) |
csorbag | 0:bf9e7b99dda5 | 86 | ->dmaLLI ( 0 ) |
csorbag | 0:bf9e7b99dda5 | 87 | ->attach_tc ( &TC1_callback ) |
csorbag | 0:bf9e7b99dda5 | 88 | ; |
csorbag | 0:bf9e7b99dda5 | 89 | |
csorbag | 0:bf9e7b99dda5 | 90 | out->printf("DMA Setup complete\n"); |
csorbag | 0:bf9e7b99dda5 | 91 | |
csorbag | 0:bf9e7b99dda5 | 92 | } |
csorbag | 0:bf9e7b99dda5 | 93 | |
csorbag | 0:bf9e7b99dda5 | 94 | |
csorbag | 0:bf9e7b99dda5 | 95 | void play(int16_t *buf,int16_t length) { |
csorbag | 0:bf9e7b99dda5 | 96 | |
csorbag | 0:bf9e7b99dda5 | 97 | |
csorbag | 0:bf9e7b99dda5 | 98 | moreToPlay = 1; |
csorbag | 0:bf9e7b99dda5 | 99 | |
csorbag | 0:bf9e7b99dda5 | 100 | if (nextToPlay - bufferStart + length >= BUFFER_SIZE) { |
csorbag | 0:bf9e7b99dda5 | 101 | nextToPlay = bufferStart; |
csorbag | 0:bf9e7b99dda5 | 102 | } |
csorbag | 0:bf9e7b99dda5 | 103 | |
csorbag | 0:bf9e7b99dda5 | 104 | memcpy(nextToPlay,buf,length*sizeof(int16_t)); |
csorbag | 0:bf9e7b99dda5 | 105 | |
csorbag | 0:bf9e7b99dda5 | 106 | transferSize=length; |
csorbag | 0:bf9e7b99dda5 | 107 | |
csorbag | 0:bf9e7b99dda5 | 108 | |
csorbag | 0:bf9e7b99dda5 | 109 | // Wait for end of playing previous packet |
csorbag | 0:bf9e7b99dda5 | 110 | while (playing) {}; |
csorbag | 0:bf9e7b99dda5 | 111 | |
csorbag | 0:bf9e7b99dda5 | 112 | playing = 1; |
csorbag | 0:bf9e7b99dda5 | 113 | moreToPlay = 0; |
csorbag | 0:bf9e7b99dda5 | 114 | |
csorbag | 0:bf9e7b99dda5 | 115 | dmaconfig->srcMemAddr ( (uint32_t) nextToPlay ); |
csorbag | 0:bf9e7b99dda5 | 116 | dmaconfig->transferSize ( length / 2); |
csorbag | 0:bf9e7b99dda5 | 117 | nextToPlay+=length*sizeof(int16_t); |
csorbag | 0:bf9e7b99dda5 | 118 | |
csorbag | 0:bf9e7b99dda5 | 119 | |
csorbag | 0:bf9e7b99dda5 | 120 | dma.Prepare(dmaconfig); |
csorbag | 0:bf9e7b99dda5 | 121 | |
csorbag | 0:bf9e7b99dda5 | 122 | |
csorbag | 0:bf9e7b99dda5 | 123 | } |
csorbag | 0:bf9e7b99dda5 | 124 | |
csorbag | 0:bf9e7b99dda5 | 125 | |
csorbag | 0:bf9e7b99dda5 | 126 | |
csorbag | 0:bf9e7b99dda5 | 127 | void TC1_callback(void) { |
csorbag | 0:bf9e7b99dda5 | 128 | |
csorbag | 0:bf9e7b99dda5 | 129 | // Get configuration pointer. |
csorbag | 0:bf9e7b99dda5 | 130 | MODDMA_Config *config = dma.getConfig(); |
csorbag | 0:bf9e7b99dda5 | 131 | |
csorbag | 0:bf9e7b99dda5 | 132 | // Finish the DMA cycle by shutting down the channel. |
csorbag | 0:bf9e7b99dda5 | 133 | dma.Disable( (MODDMA::CHANNELS)config->channelNum() ); |
csorbag | 0:bf9e7b99dda5 | 134 | |
csorbag | 0:bf9e7b99dda5 | 135 | |
csorbag | 0:bf9e7b99dda5 | 136 | // Clear DMA IRQ flags. |
csorbag | 0:bf9e7b99dda5 | 137 | if (dma.irqType() == MODDMA::TcIrq) dma.clearTcIrq(); |
csorbag | 0:bf9e7b99dda5 | 138 | |
csorbag | 0:bf9e7b99dda5 | 139 | playing = 0; |
csorbag | 0:bf9e7b99dda5 | 140 | |
csorbag | 0:bf9e7b99dda5 | 141 | if (!moreToPlay) { |
csorbag | 0:bf9e7b99dda5 | 142 | LPC_I2S->I2STXFIFO = 0x0; |
csorbag | 0:bf9e7b99dda5 | 143 | led3 = !led3; |
csorbag | 0:bf9e7b99dda5 | 144 | } |
csorbag | 0:bf9e7b99dda5 | 145 | } |