X-Git-Url: http://git.droids-corp.org/?p=protos%2Frc_servos.git;a=blobdiff_plain;f=main.c;h=ad0af0546c064a85832edb87ff925aa29c354c36;hp=e733e81587186f979731ddab067dd862ba746d3d;hb=f9f1d9f0311d8c84e8f2accac4ba5ea5f5481d6a;hpb=98801c6e5d8a04f06c7e3f3d9de73919b593e4eb

diff --git a/main.c b/main.c
index e733e81..ad0af05 100644
--- a/main.c
+++ b/main.c
@@ -1,4 +1,5 @@
 #include <aversive.h>
+#include <aversive/wait.h>
 
 struct servo {
 	uint8_t bit;
@@ -7,32 +8,122 @@ struct servo {
 
 static struct servo servo_table[] = {
 	{
-		.bit = 0,
-		.command = 0,
+		.bit = 2,
+		.command = 300,
+	},
+	{
+		.bit = 3,
+		.command = 700,
 	},
 	{
-		.bit = 1,
+		.bit = 4,
 		.command = 512,
 	},
 	{
-		.bit = 2,
-		.command = 1023,
+		.bit = 5,
+		.command = 512,
+	},
+	{
+		.bit = 6,
+		.command = 512,
+	},
+	{
+		.bit = 7,
+		.command = 512,
 	},
 };
-static volatile uint8_t rxbuf[16];
-static volatile uint8_t rxlen;
-static volatile uint8_t portval;
+#define NB_SERVO (sizeof(servo_table)/sizeof(*servo_table))
+
+static volatile uint8_t bypass;
 static volatile uint8_t done;
+static volatile uint8_t portval;
+static volatile uint8_t rxidx;
+
+#define BYPASS_ENABLE 14
+#define BYPASS_DISABLE 15
+
+#define LED_ON() do { PORTB |= 0x02; } while(0)
+#define LED_OFF() do { PORTB &= ~0x02; } while(0)
+
+/*
+ * 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.
+ *
+ * Commands 0 to NB_SERVO are to set the value of servo.
+ * Command 14 is to enable bypass mode.
+ * Command 15 is to disable bypass mode.
+ */
+static volatile union {
+	uint8_t u8;
+	struct {
+		/* inverted: little endian */
+		uint8_t val_msb:3;
+		uint8_t cmd_num:4;
+		uint8_t zero:1;
+	};
+} byte0;
+
+static volatile union {
+	uint8_t u8;
+	struct {
+		/* inverted: little endian */
+		uint8_t val_lsb:7;
+		uint8_t one:1;
+	};
+} byte1;
 
 SIGNAL(TIMER1_COMPA_vect)
 {
-	PORTC = portval;
+	PORTD = portval;
 	TIMSK1 &= ~_BV(OCIE1A);
 	done = 1;
 }
 
 static void poll_spi(void)
 {
+	uint8_t c;
+
+	/* reception complete ? */
+	if (!(SPSR & (1<<SPIF)))
+		return;
+
+	c = SPDR;
+	if ((rxidx == 0) && (c & 0x80)) {
+		rxidx = 0;
+		return; /* drop */
+	}
+	if ((rxidx == 1) && ((c & 0x80) == 0)) {
+		rxidx = 0;
+		return; /* drop */
+	}
+
+	if (rxidx == 0) {
+		byte0.u8 = c;
+	}
+	else {
+		uint16_t val;
+
+		byte1.u8 = c;
+
+		/* process command */
+
+		if (byte0.cmd_num < NB_SERVO) {
+			val = (uint16_t)byte0.val_msb << 7;
+			val += byte1.val_lsb;
+			servo_table[byte0.cmd_num].command = val;
+		}
+		else if (byte0.cmd_num == BYPASS_ENABLE) {
+			bypass = 1;
+		}
+		else if (byte0.cmd_num == BYPASS_DISABLE) {
+			bypass = 0;
+		}
+	}
+
+	rxidx ^= 1;
 }
 
 static void load_timer_at(uint16_t t)
@@ -68,8 +159,20 @@ int main(void)
 	uint8_t i;
 	uint8_t t, diff;
 
-	DDRB = 0x20;
-	DDRC = 0x7;
+	/* LED */
+	DDRB = 0x02;
+
+#if 0 /* LED debug */
+	while (1) {
+		LED_ON();
+		wait_ms(100);
+		LED_OFF();
+		wait_ms(100);
+	}
+#endif
+
+	/* servo outputs PD2-PD7 */
+	DDRD = 0xfc;
 
 	/* start timer1 at clk/1 (8Mhz) */
 	TCNT1 = 0;
@@ -79,11 +182,15 @@ int main(void)
 	TCNT0 = 0;
 	TCCR0B = _BV(CS02) | _BV(CS00);
 
+	/* enable spi (don't set unused MISO as output) */
+	SPCR = _BV(SPE);
+
 	sei();
 
+	bypass = 0;
 	while (1) {
 		t = TCNT0;
-		for (i = 0; i < sizeof(servo_table)/sizeof(*servo_table); i++) {
+		for (i = 0; i < NB_SERVO; i++) {
 			do_one_servo(&servo_table[i]);
 		}
 		/* wait 20 ms */
@@ -93,6 +200,13 @@ int main(void)
 				break;
 			poll_spi();
 		}
+		/* bypass mode */
+		while (bypass == 1) {
+			LED_ON();
+			PORTD = (PINC & 0x3f) << 2;
+			poll_spi();
+		}
+		LED_OFF();
 	}
 
 	return 0;