lightctrl: use WDT

the CPU seems to get stuck for no apparent reason, right in the middle
of a line on the serial console... weird.  let's enable the WDT as a
temporary band-aid.

3 files changed, 54 insertions, 0 deletions

diff --git a/dali_ctl.c b/dali_ctl.c
index ed23ce1..b5eb66b 100644
--- a/dali_ctl.c
+++ b/dali_ctl.c
@@ -41,6 +41,8 @@ static void dali_search_byte(uint16_t cmd)
 	uint8_t bit = 0x80;
 
 	while (bit) {
+		wdt_reset();
+
 		dali_twice(cmd | (dali_s_byte & ~bit));
 		if (dali_compare()) {
 			_delay_ms(1);
@@ -92,6 +94,8 @@ static void dali_search(void)
 	do {
 		dali_search_single();
 		if (!dali_s_notfound) {
+			wdt_reset();
+
 			uart_puts("dali scan found\t\t");
 			uart_puthex(dali_sh);
 			uart_puthex(dali_sm);
@@ -130,10 +134,14 @@ static void dali_search(void)
 					dali_map[addr >> 3] |= 1 << (addr & 0x7);
 			} else
 				uart_puts(" error\n");
+
+			wdt_reset();
 			dali_send(DALI_C_WITHDRAW);
 		}
 	} while (!dali_s_notfound);
 
+	wdt_reset();
+
 	dali_twice(DALI_C_TERMINATE);
 	uart_puts("dali scan end\n");
 
diff --git a/lightctrl.c b/lightctrl.c
index 9e8d234..659ac26 100644
--- a/lightctrl.c
+++ b/lightctrl.c
@@ -5,6 +5,7 @@
 #include <avr/interrupt.h>
 #include <avr/pgmspace.h>
 #include <avr/eeprom.h>
+#include <avr/wdt.h>
 #include <util/delay.h>
 
 const uint8_t __signature[3] __attribute__((section (".signature"), used)) =
@@ -27,6 +28,7 @@ const uint8_t __signature[3] __attribute__((section (".signature"), used)) =
 #include "dali_ctl.c"
 #include "dim.c"
 #include "can.c"
+#include "wdt.c"
 
 static void can_rx_exec(void)
 {
@@ -65,6 +67,8 @@ static void can_rx_exec(void)
 
 int main(void)
 {
+	wdt_init();
+
 	DDRD |= (1 << D_LED1) | (1 << D_LED2 ) | (1 << D_TXD) | (1 << D_DALIO);
 	PORTD |= (1 << D_LED1) | (1 << D_TAST);
 	PORTD &= ~(1 << D_LED1);
@@ -76,8 +80,24 @@ int main(void)
 
 	sei();
 
+	uart_puts("\nreset from");
+	if (MCUSR & (1 << WDRF))
+		uart_puts(" WDT");
+	if (MCUSR & (1 << BORF))
+		uart_puts(" BO");
+	if (MCUSR & (1 << EXTRF))
+		uart_puts(" EXT");
+	if (MCUSR & (1 << PORF))
+		uart_puts(" POR");
+	MCUSR = 0;
+
+	uart_puts("\nwdt_generation ");
+	uart_puthex(wdt_generation);
+
 	uart_puts("\ndelay...\n");
+	wdt_reset();
 	_delay_ms(1000);
+	wdt_reset();
 	uart_puts("\ninit done\n");
 
 	can_init();
@@ -88,6 +108,7 @@ int main(void)
 	uint16_t ctr = 0;
 
 	while (1) {
+		wdt_reset();
 		if (canint) {
 			canint = false;
 			can_int();
diff --git a/wdt.c b/wdt.c
new file mode 100644
index 0000000..f815b71
--- /dev/null
+++ b/wdt.c
@@ -0,0 +1,25 @@
+
+static uint8_t wdt_generation __attribute__((section (".noinit")));
+
+static void wdt_init(void)
+{
+	uint8_t temp;
+	/* timed sequence. bit 4: WDCE, bit 3: WDE,
+	 * 0x07 = WDP2 | WDP1 | WDP0 = 2s */
+	asm volatile ("\n\
+WDTCSR	= 0x60\n\
+WDCE	= 4\n\
+WDE	= 3\n\
+		wdr	\n\
+			\n\
+		ldi	%[temp], (1 << WDCE) | (1 << WDE)	\n\
+		sts	WDTCSR, %[temp]				\n\
+			\n\
+		ldi	%[temp], (1 << WDE) | 0x07		\n\
+		sts	WDTCSR, %[temp]				\n\
+	" : [temp] "=r" (temp) :  : "memory");
+
+	if (MCUSR & (1 << WDRF))
+		wdt_generation++;
+}
+