diff core/PRU.cpp @ 12:a6beeba3a648

Initial support for higher matrix sample rates by reducing the number of channels. Input not tested yet, and not all examples updated to new format.

--- a/core/PRU.cpp	Thu Nov 13 16:02:59 2014 +0100
+++ b/core/PRU.cpp	Thu Jan 22 19:00:22 2015 +0000
@@ -50,8 +50,9 @@
 #define PRU_LED_PIN_MASK	7
 #define PRU_FRAME_COUNT		8
 #define PRU_USE_SPI			9
+#define PRU_SPI_NUM_CHANNELS 10
 
-#define PRU_SAMPLE_INTERVAL_NS 45351	// 22050Hz per SPI sample = 45.351us
+#define PRU_SAMPLE_INTERVAL_NS 11338	// 88200Hz per SPI sample = 11.338us
 
 #define GPIO0_ADDRESS 		0x44E07000
 #define GPIO1_ADDRESS 		0x4804C000
@@ -79,7 +80,7 @@
 // Constructor: specify a PRU number (0 or 1)
 PRU::PRU()
 : pru_number(0), running(false), spi_enabled(false), gpio_enabled(false), led_enabled(false),
-  gpio_test_pin_enabled(false), xenomai_gpio_fd(-1), xenomai_gpio(0)
+  gpio_test_pin_enabled(false), spi_num_channels(0), xenomai_gpio_fd(-1), xenomai_gpio(0)
 {
 
 }
@@ -224,7 +225,7 @@
 }
 
 // Initialise and open the PRU
-int PRU::initialise(int pru_num, int frames_per_buffer, bool xenomai_test_pin)
+int PRU::initialise(int pru_num, int frames_per_buffer, int spi_channels, bool xenomai_test_pin)
 {
 	uint32_t *pruMem = 0;
 
@@ -235,6 +236,13 @@
 
 	pru_number = pru_num;
 
+	/* Set number of SPI ADC / DAC channels to use. This implicitly
+	 * also determines the sample rate relative to the audio clock
+	 * (half audio clock for 8 channels, full audio clock for 4,
+	 * double audio clock for 2)
+	 */
+	spi_num_channels = spi_channels;
+
     /* Initialize structure used by prussdrv_pruintc_intc   */
     /* PRUSS_INTC_INITDATA is found in pruss_intc_mapping.h */
     tpruss_intc_initdata pruss_intc_initdata = PRUSS_INTC_INITDATA;
@@ -250,22 +258,22 @@
     prussdrv_pruintc_init(&pruss_intc_initdata);
 
     spi_buffer_frames = frames_per_buffer;
-    audio_buffer_frames = spi_buffer_frames * 2;
+    audio_buffer_frames = spi_buffer_frames * spi_num_channels / 4;
 
     /* Map PRU memory to pointers */
 	prussdrv_map_prumem (PRUSS0_SHARED_DATARAM, (void **)&pruMem);
     pru_buffer_comm = (uint32_t *)&pruMem[PRU_MEM_COMM_OFFSET/sizeof(uint32_t)];
 	pru_buffer_audio_dac = (int16_t *)&pruMem[PRU_MEM_MCASP_OFFSET/sizeof(uint32_t)];
 
-	/* ADC memory starts 2(ch)*2(buffers)*2(samples/spi)*bufsize samples later */
-	pru_buffer_audio_adc = &pru_buffer_audio_dac[8 * spi_buffer_frames];
+	/* ADC memory starts 2(ch)*2(buffers)*bufsize samples later */
+	pru_buffer_audio_adc = &pru_buffer_audio_dac[4 * audio_buffer_frames];
 
 	if(spi_enabled) {
 		prussdrv_map_prumem (pru_number == 0 ? PRUSS0_PRU0_DATARAM : PRUSS0_PRU1_DATARAM, (void **)&pruMem);
 		pru_buffer_spi_dac = (uint16_t *)&pruMem[PRU_MEM_DAC_OFFSET/sizeof(uint32_t)];
 
-		/* ADC memory starts after 8(ch)*2(buffers)*bufsize samples */
-		pru_buffer_spi_adc = &pru_buffer_spi_dac[16 * spi_buffer_frames];
+		/* ADC memory starts after N(ch)*2(buffers)*bufsize samples */
+		pru_buffer_spi_adc = &pru_buffer_spi_dac[2 * spi_num_channels * spi_buffer_frames];
 	}
 	else {
 		pru_buffer_spi_dac = pru_buffer_spi_adc = 0;
@@ -288,9 +296,11 @@
     }
     if(spi_enabled) {
     	pru_buffer_comm[PRU_USE_SPI] = 1;
+    	pru_buffer_comm[PRU_SPI_NUM_CHANNELS] = spi_num_channels;
     }
     else {
     	pru_buffer_comm[PRU_USE_SPI] = 0;
+    	pru_buffer_comm[PRU_SPI_NUM_CHANNELS] = 0;
     }
 
     /* Clear ADC and DAC memory */
@@ -340,7 +350,7 @@
 void PRU::loop()
 {
 	// Polling interval is 1/4 of the period
-	RTIME sleepTime = PRU_SAMPLE_INTERVAL_NS * spi_buffer_frames / 4;
+	RTIME sleepTime = PRU_SAMPLE_INTERVAL_NS * (spi_num_channels / 2) * spi_buffer_frames / 4;
 	float *audioInBuffer, *audioOutBuffer;
 
 	audioInBuffer = (float *)malloc(2 * audio_buffer_frames * sizeof(float));
@@ -410,7 +420,7 @@
 
 		if(spi_enabled)
 			render(spi_buffer_frames, audio_buffer_frames, audioInBuffer, audioOutBuffer,
-					&pru_buffer_spi_adc[spi_buffer_frames * 8], &pru_buffer_spi_dac[spi_buffer_frames * 8]);
+					&pru_buffer_spi_adc[spi_buffer_frames * spi_num_channels], &pru_buffer_spi_dac[spi_buffer_frames * spi_num_channels]);
 		else
 			render(0, audio_buffer_frames, audioInBuffer, audioOutBuffer, 0, 0);