STM32F7: Fix all time values to be in units of the sample clock, not …

…the sysclk.

Sysclk just happened to be correct for F1, but is 3x too fast for F7.

src/floppy.c

@@ -18,6 +18,12 @@
 #define configure_pin(pin, type) \
     gpio_configure_pin(gpio_##pin, pin_##pin, type)
 
+#define SAMPLE_MHZ 72
+#define TIM_PSC (SYSCLK_MHZ / SAMPLE_MHZ)
+#define sample_ns(x) (((x) * SAMPLE_MHZ) / 1000)
+#define sample_us(x) ((x) * SAMPLE_MHZ)
+#define time_from_samples(x) ((x) * TIME_MHZ / SAMPLE_MHZ)
+
 #if STM32F == 1
 #include "floppy_f1.c"
 #elif STM32F == 7
@@ -348,9 +354,9 @@ static void rdata_encode_flux(void)
      * flux timestamp. */
     if (sizeof(timcnt_t) == sizeof(uint16_t)) {
         curr = tim_rdata->cnt - prev;
-        if (unlikely(curr > sysclk_us(400))) {
-            prev += sysclk_us(200);
-            ticks += sysclk_us(200);
+        if (unlikely(curr > sample_us(400))) {
+            prev += sample_us(200);
+            ticks += sample_us(200);
         }
     }
 
@@ -475,7 +481,7 @@ static unsigned int _wdata_decode_flux(timcnt_t *tbuf, unsigned int nr)
         return 0;
 
     if (rw.no_flux_area) {
-        unsigned int nfa_pulse = sysclk_ns(1250);
+        unsigned int nfa_pulse = sample_ns(1250);
         while (ticks >= nfa_pulse) {
             *tbuf++ = nfa_pulse - 1;
             ticks -= nfa_pulse;
@@ -514,10 +520,10 @@ static unsigned int _wdata_decode_flux(timcnt_t *tbuf, unsigned int nr)
         }
 
         ticks += x;
-        if (ticks < sysclk_ns(800))
+        if (ticks < sample_ns(800))
             continue;
 
-        if (ticks > sysclk_us(150)) {
+        if (ticks > sample_us(150)) {
             rw.no_flux_area = TRUE;
             goto out;
         }
@@ -599,7 +605,7 @@ static uint8_t floppy_write_prep(struct gw_write_flux *wf)
     memset(&rw, 0, sizeof(rw));
     rw.status = ACK_OKAY;
 
-    index.delay = time_sysclk(wf->index_delay_ticks);
+    index.delay = time_from_samples(wf->index_delay_ticks);
     rw.terminate_at_index = wf->terminate_at_index;
 
     return ACK_OKAY;

src/floppy_f1.c

@@ -53,7 +53,6 @@ static unsigned int GPI_bus;
 #define dma_wdata   (dma1->ch3)
 
 typedef uint16_t timcnt_t;
-#define TIM_PSC 0
 
 #define irq_index 23
 void IRQ_23(void) __attribute__((alias("IRQ_INDEX_changed"))); /* EXTI9_5 */
@@ -83,13 +82,13 @@ static void floppy_mcu_init(void)
 static void rdata_prep(void)
 {
     /* RDATA Timer setup: 
-     * The counter runs from 0x0000-0xFFFF inclusive at full SYSCLK rate.
+     * The counter runs from 0x0000-0xFFFF inclusive at SAMPLE rate.
      *  
      * Ch.2 (RDATA) is in Input Capture mode, sampling on every clock and with
      * no input prescaling or filtering. Samples are captured on the falling 
      * edge of the input (CCxP=1). DMA is used to copy the sample into a ring
      * buffer for batch processing in the DMA-completion ISR. */
-    tim_rdata->psc = 0;
+    tim_rdata->psc = TIM_PSC-1;
     tim_rdata->arr = 0xffff;
     tim_rdata->ccmr1 = TIM_CCMR1_CC2S(TIM_CCS_INPUT_TI1);
     tim_rdata->dier = TIM_DIER_CC2DE;
@@ -113,17 +112,17 @@ static void rdata_prep(void)
 static void wdata_prep(void)
 {
     /* WDATA Timer setup:
-     * The counter is incremented at full SYSCLK rate. 
+     * The counter is incremented at SAMPLE rate. 
      *  
      * Ch.1 (WDATA) is in PWM mode 1. It outputs O_TRUE for 400ns and then 
      * O_FALSE until the counter reloads. By changing the ARR via DMA we alter
      * the time between (fixed-width) O_TRUE pulses, mimicking floppy drive 
      * timings. */
-    tim_wdata->psc = 0;
+    tim_wdata->psc = TIM_PSC-1;
     tim_wdata->ccmr1 = (TIM_CCMR1_CC1S(TIM_CCS_OUTPUT) |
                         TIM_CCMR1_OC1M(TIM_OCM_PWM1));
     tim_wdata->ccer = TIM_CCER_CC1E | ((O_TRUE==0) ? TIM_CCER_CC1P : 0);
-    tim_wdata->ccr1 = sysclk_ns(400);
+    tim_wdata->ccr1 = sample_ns(400);
     tim_wdata->dier = TIM_DIER_UDE;
     tim_wdata->cr2 = 0;
 }

src/floppy_f7.c

@@ -57,7 +57,6 @@
 #define dma_wdata   (dma1->str[1])
 
 typedef uint32_t timcnt_t;
-#define TIM_PSC (SYSCLK_MHZ/72)
 
 #define irq_index 8
 void IRQ_8(void) __attribute__((alias("IRQ_INDEX_changed"))); /* EXTI2 */
@@ -83,8 +82,7 @@ static void floppy_mcu_init(void)
 static void rdata_prep(void)
 {
     /* RDATA Timer setup: 
-     * The counter runs from 0x00000000-0xFFFFFFFF inclusive.
-     * The prescaler is used to reduce the clock rate to 72MHz.
+     * The counter runs from 0x00000000-0xFFFFFFFF inclusive at SAMPLE rate.
      *  
      * Ch.1 (RDATA) is in Input Capture mode, sampling on every clock and with
      * no input prescaling or filtering. Samples are captured on the falling 
@@ -115,7 +113,7 @@ static void rdata_prep(void)
 static void wdata_prep(void)
 {
     /* WDATA Timer setup:
-     * The counter is incremented at 72MHz.
+     * The counter is incremented at SAMPLE rate.
      *  
      * Ch.3 (WDATA) is in PWM mode 1. It outputs O_TRUE for 400ns and then 
      * O_FALSE until the counter reloads. By changing the ARR via DMA we alter
@@ -125,7 +123,7 @@ static void wdata_prep(void)
     tim_wdata->ccmr2 = (TIM_CCMR2_CC3S(TIM_CCS_OUTPUT) |
                         TIM_CCMR2_OC3M(TIM_OCM_PWM1));
     tim_wdata->ccer = TIM_CCER_CC3E | ((O_TRUE==0) ? TIM_CCER_CC3P : 0);
-    tim_wdata->ccr3 = sysclk_ns(400) / TIM_PSC;
+    tim_wdata->ccr3 = sample_ns(400);
     tim_wdata->dier = TIM_DIER_UDE;
     tim_wdata->cr2 = 0;
 }