Add comment. Clean up. Sync dac with the timer.

[bertos.git] / bertos / cpu / cortex-m3 / drv / dac_sam3.c

diff --git a/bertos/cpu/cortex-m3/drv/dac_sam3.c b/bertos/cpu/cortex-m3/drv/dac_sam3.c
index 9a9ec02509e4d56efcefa16793b0c00397c91917..89f5aa71253b92b8901c60169bb1b67b309556bf 100644 (file)
--- a/bertos/cpu/cortex-m3/drv/dac_sam3.c
+++ b/bertos/cpu/cortex-m3/drv/dac_sam3.c
@@ -50,6 +50,8 @@
 #include <drv/dac.h>
 #include <drv/irq_cm3.h>
 
+#include <cpu/types.h>
+
 #include <io/cm3.h>
 
 #include <string.h>
@@ -57,6 +59,7 @@
 struct DacHardware
 {
        uint16_t channels;
+       uint32_t rate;
        bool end;
 };
 
@@ -90,42 +93,52 @@ struct DacHardware dac_hw;
        #error unimplemented pwm triger select.
 #endif
 
-INLINE void tc_setup(uint32_t freq)
+INLINE void tc_setup(uint32_t freq, size_t n_sample)
 {
        pmc_periphEnable(DAC_TC_ID);
 
-    /*  Disable TC clock */
-    DAC_TC_CCR = TC_CCR_CLKDIS;
-    /*  Disable interrupts */
-    DAC_TC_IDR = 0xFFFFFFFF;
-    /*  Clear status register */
-    volatile uint32_t dummy = DAC_TC_SR;
+       /*  Disable TC clock */
+       DAC_TC_CCR = TC_CCR_CLKDIS;
+       /*  Disable interrupts */
+       DAC_TC_IDR = 0xFFFFFFFF;
+       /*  Clear status register */
+       volatile uint32_t dummy = DAC_TC_SR;
        (void)dummy;
 
        /*
         * Setup the timer counter:
-        * - select clock TCLK1
+        * - select clock TCLK1 (MCK/2)
         * - enable wave form mode
         * - RA compare effect SET
         * - RC compare effect CLEAR
         * - UP mode with automatic trigger on RC Compare
         */
-    DAC_TC_CMR = BV(TC_TIMER_CLOCK1) | BV(TC_CMR_WAVE) | TC_CMR_ACPA_SET | TC_CMR_ACPC_CLEAR | BV(TC_CMR_CPCTRG);
+       DAC_TC_CMR = TC_TIMER_CLOCK1 | BV(TC_CMR_WAVE) | TC_CMR_ACPA_SET | TC_CMR_ACPC_CLEAR | BV(TC_CMR_CPCTRG);
+
+       /*
+        * Compute the sample frequency
+        * the RC counter will update every MCK/2 (see above)
+        * so to convert one sample at the user freq we generate
+        * the trigger every TC_CLK / (numer_of_sample * user_freq)
+        * where TC_CLK = MCK / 2.
+        */
+       uint32_t rc = DIV_ROUND((CPU_FREQ / 2), n_sample * freq);
+       DAC_TC_RC = rc;
+       /* generate the square wave with duty = 50% */
+       DAC_TC_RA = DIV_ROUND(50 * rc, 100);
 
-       /* Compute the sample frequency */
-    uint32_t rc = (CPU_FREQ / 8) / (freq * 1000);
-    DAC_TC_RC = rc;
-    DAC_TC_RA = 50 * rc / 100;
+       PIOB_PDR = BV(25);
+       PIO_PERIPH_SEL(PIOB_BASE, BV(25), PIO_PERIPH_B);
 }
 
 INLINE void tc_start(void)
 {
-    DAC_TC_CCR =  BV(TC_CCR_CLKEN)| BV(TC_CCR_SWTRG);
+       DAC_TC_CCR =  BV(TC_CCR_CLKEN)| BV(TC_CCR_SWTRG);
 }
 
 INLINE void tc_stop(void)
 {
-    DAC_TC_CCR =  BV(TC_CCR_CLKDIS);
+       DAC_TC_CCR =  BV(TC_CCR_CLKDIS);
 }
 
 static int sam3x_dac_write(struct Dac *dac, unsigned channel, uint16_t sample)
@@ -155,8 +168,7 @@ static void sam3x_dac_setSampleRate(struct Dac *dac, uint32_t rate)
 
        /* Eneble hw trigger */
        DACC_MR |= BV(DACC_TRGEN) | (CONFIG_DAC_TIMER << DACC_TRGSEL_SHIFT);
-       kprintf("%08lx\n", DACC_MR);
-       tc_setup(rate);
+       dac->hw->rate = rate;
 }
 
 static void sam3x_dac_conversion(struct Dac *dac, void *buf, size_t len)
@@ -169,7 +181,8 @@ static void sam3x_dac_conversion(struct Dac *dac, void *buf, size_t len)
 
        DACC_CHER |= dac->hw->channels;
 
-       /* Start syncro timer for the dac */
+       /* setup timer and start it */
+       tc_setup(dac->hw->rate, len);
        tc_start();
 
        /* Setup dma and start it */
@@ -180,15 +193,21 @@ static void sam3x_dac_conversion(struct Dac *dac, void *buf, size_t len)
 
 static bool sam3x_dac_isFinished(struct Dac *dac)
 {
+       (void)dac;
        return 0;
 }
 
 static void sam3x_dac_start(struct Dac *dac, void *buf, size_t len, size_t slicelen)
 {
+       (void)dac;
+       (void)buf;
+       (void)len;
+       (void)slicelen;
 }
 
 static void sam3x_dac_stop(struct Dac *dac)
 {
+       (void)dac;
 }