X-Git-Url: http://git.droids-corp.org/?a=blobdiff_plain;ds=sidebyside;f=main.c;h=9c368d5aa27b08f19da25d12c75249adc95f99ba;hb=3be0a345c40d7ef9b20e7749a0c73db14f2927e0;hp=35098746f4563207d3510a44a96dd3d00b59e417;hpb=e8dc3448b547f715e33f62ae690a9408b4e90a70;p=protos%2Frc_servos.git

diff --git a/main.c b/main.c
index 3509874..9c368d5 100644
--- a/main.c
+++ b/main.c
@@ -39,6 +39,10 @@ static volatile uint8_t done;
 static uint8_t portval;
 static uint8_t rxidx;
 
+static uint8_t icp_idx = NB_SERVO;
+static uint16_t icp_servos[NB_SERVO];
+static uint16_t icp_prev;
+
 #define BYPASS_ENABLE 14
 #define BYPASS_DISABLE 15
 
@@ -48,11 +52,13 @@ static uint8_t rxidx;
 /*
  * SPI protocol:
  *
- * A command is stored on 2 bytes. The first one has its msb to 0, and the
- * second one to 1. The first received byte contains the command number, and the
- * msb of the servo value. The second byte contains the lsb of the servo value.
+ * A command is stored on 2 bytes (except command 0). The first byte
+ * has its most significant bit to 0, and the second one to 1. The
+ * first received byte contains the command number, and the msb of the
+ * servo value. The second byte contains the lsb of the servo value.
  *
- * Commands 0 to NB_SERVO are to set the value of servo.
+ * Command 0 is only one byte long, it means "I have nothing to say".
+ * Commands 1 to NB_SERVO+1 are to set the value of servo.
  * Command 14 is to enable bypass mode.
  * Command 15 is to disable bypass mode.
  */
@@ -102,6 +108,10 @@ static void poll_spi(void)
 
 	if (rxidx == 0) {
 		byte0.u8 = c;
+
+		/* command num 0 is ignored */
+		if (byte0.cmd_num == 0)
+			return;
 	}
 	else {
 		uint16_t val;
@@ -110,10 +120,10 @@ static void poll_spi(void)
 
 		/* process command */
 
-		if (byte0.cmd_num < NB_SERVO) {
+		if (byte0.cmd_num < NB_SERVO+1) {
 			val = (uint16_t)byte0.val_msb << 7;
 			val += byte1.val_lsb;
-			servo_table[byte0.cmd_num].command = val;
+			servo_table[byte0.cmd_num-1].command = val;
 		}
 		else if (byte0.cmd_num == BYPASS_ENABLE) {
 			bypass = 1;
@@ -126,6 +136,53 @@ static void poll_spi(void)
 	rxidx ^= 1;
 }
 
+static void poll_input_capture(void)
+{
+	uint16_t icp, diff;
+	uint8_t rising;
+
+	/* no new sample, return */
+	if ((TIFR1 & _BV(ICF1)) == 0)
+		return;
+
+	sei();
+	icp = ICR1;
+	cli();
+
+	rising = TCCR1B & _BV(ICES1);
+
+	/* change the edge type */
+	TCCR1B ^= _BV(ICES1);
+
+	/* clear the flag */
+	TIFR1 = TIFR1 | _BV(ICF1);
+
+	diff = icp - icp_prev;
+	icp_prev = icp;
+
+	/* a rising edge with at least 2ms of state 0 means that we
+	 * get the first servo */
+	if (rising == 1 && diff > 2000) {
+		icp_idx = 0;
+		return;
+	}
+
+	/* get the value for the servo */
+	if (rising == 0 && icp_idx < NB_SERVO) {
+		if (diff < 1000)
+			icp_servos[icp_idx] = 0;
+		else
+			icp_servos[icp_idx] = diff - 1000;
+		icp_idx++;
+	}
+}
+
+static void poll(void)
+{
+	poll_spi();
+	poll_input_capture();
+}
+
 static void load_timer_at(uint16_t t)
 {
 	OCR1A = t;
@@ -143,7 +200,7 @@ static void do_one_servo(struct servo *s)
 	t = TCNT1;
 	load_timer_at(t + 20);
 	while (done == 0)
-		poll_spi();
+		poll();
 
 	/* reset bit */
 	done = 0;
@@ -151,7 +208,7 @@ static void do_one_servo(struct servo *s)
 	//portval = PORTC & (~(1 << s->bit));
 	load_timer_at(t + 20 + 1000 + s->command);
 	while (done == 0)
-		poll_spi();
+		poll();
 }
 
 int main(void)
@@ -178,9 +235,10 @@ int main(void)
 	/* servo outputs PD2-PD7 */
 	DDRD = 0xfc;
 
-	/* start timer1 at clk/8 (1Mhz) */
+	/* start timer1 at clk/8 (1Mhz), enable noise canceler on
+	 * input capture, capture rising edge */
 	TCNT1 = 0;
-	TCCR1B = _BV(CS11);
+	TCCR1B = _BV(CS11) | _BV(ICNC1) | _BV(ICES1);
 
 	/* start timer0 at clk/1024 (~8Khz) */
 	TCNT0 = 0;
@@ -202,7 +260,7 @@ int main(void)
 			diff = TCNT0 - t;
 			if (diff >= 160)
 				break;
-			poll_spi();
+			poll();
 		}
 		/* bypass mode */
 		if (bypass == 1) {
@@ -213,7 +271,7 @@ int main(void)
 				tmp &= 0x3f;
 				tmp <<= 2;
 				PORTD = tmp;
-				poll_spi();
+				poll();
 			}
 			LED_OFF();
 		}