Makefile

@@ -16,8 +16,7 @@ CC=avr-gcc -Wall -MMD -std=c99 -O3 -mmcu=$(MCU) \
   -funsigned-char \
   -funsigned-bitfields \
   -fpack-struct \
-  -fshort-enums \
+  -fshort-enums
-  -fverbose-asm
 
 CFLAGS = $($*_CFLAGS) $(DEBUG)
 

chaos/chaos.c

@@ -66,7 +66,7 @@ static inline void avrdac_set(unsigned int d)
 }
 
 #include <avr/wdt.h>
-void wdt_init(unsigned char mode);
+unsigned char wdt_init(unsigned char mode);
 unsigned char wdt_count;
 unsigned char wdt_saved;
 
@@ -74,7 +74,8 @@ enum {
 	WDT_MODE_LIVE = 2, // = any command kick
 	WDT_MODE_KICK = 3, // only 'W' command kicks
 	WDT_MODE_HV   = 4, // ≥ 'H' command kicks
-	WDT_MODE_RAMP = 5, // ≥ dac_ramp kicks
+	WDT_MODE_FULL = 5, // ≥ do not allow HV reset to be interrupted
+	WDT_MODE_RAMP = 6, // ≥ dac_ramp kicks
 };
 
 static inline void wdt_kick()
@@ -88,6 +89,7 @@ struct {
 	unsigned int dac_nominal;
 	unsigned int dac_off;
 	unsigned int tick_period;
+	unsigned int wdt_tick_period;
 	unsigned char flags;
 	unsigned char flags2;
 	unsigned char wdt_timeout;
@@ -109,11 +111,14 @@ struct {
 	unsigned char hvosc_dc;
 	unsigned char padding[2];
 } conf = {
-	.wdt_timeout     = 120,   // 2 min
+	.wdt_timeout     = 10,    // 2 min
+	.wdt_tick_period = TICK_NS(100000L),   // 100µs
 	.tick_period     = TICK_NS(10000000L), //  10ms
 	.avradc          = 0x7f,  // off
 	.adcconf         = 0x8500,// RST
 	.ddrc            = 2,     // OC1B HVOSC
+	.hvosc_freq      = 51,
+	.hvosc_dc        = 9,
 };
 
 enum {
@@ -159,26 +164,10 @@ void conf_init()
 	}
 }
 
-int hv_is_safe()
+static inline void led_hv()
-{
-	return !hvosc_is_on() && conf.dac==conf.dac_off;
-}
-
-void hv_safe()
-{
-	hvosc_init(0, 0);
-	if (conf.flags2 & FLAG2_PC_HV)
-		PORTC = conf.portc_off;
-	unsigned char sreg = disable_irq();
-	ltc1655_cmd(INT2FRAME(conf.dac_off));
-	conf.dac = conf.dac_off;
-	enable_irq(sreg);
-}
-
-void toggle_hv_led()
 {
 	if (conf.flags2 & FLAG2_HVLED) {
-		if (hv_is_safe())
+		if (conf.dac == conf.dac_off)
 			led_toggle(LED_GREEN);
 		else
 			led_toggle(LED_RED);
@@ -211,8 +200,8 @@ int main()
 		const char *p;
 		spi_slave_Rx(cmd, 3);
 		resp[0] = cmd[0];
-		toggle_hv_led();
 		sreg = disable_irq();
+		led_hv();
 		if (conf.wdt_mode == WDT_MODE_LIVE)
 			wdt_kick();
 		switch (cmd[0]) {
@@ -265,12 +254,13 @@ int main()
 			hvosc_init(conf.hvosc_freq, conf.hvosc_dc);
 			break;
 		case 'I':
-		case 'i':
 			int2frame(tick_freq(), resp+1);
-			if (upcase(cmd[0])) {
+			conf.tick_period = frame2int(cmd+1);
-				conf.tick_period = frame2int(cmd+1);
+			tick_init(conf.tick_period);
-				tick_init(conf.tick_period);
+			break;
-			}
+		case 'i':
+			int2frame(conf.wdt_tick_period, resp+1);
+			conf.wdt_tick_period = frame2int(cmd+1);
 			break;
 		case 'A':
 			ads8688_cmd(cmd+1, resp+1);
@@ -321,12 +311,10 @@ int main()
 			resp[2] = conf.wdt_timeout;
 			if (cmd[2])
 				conf.wdt_timeout = cmd[2];
-			if (cmd[1]) {
+			if (cmd[1])
-				wdt_init(cmd[1]);
+				sreg = wdt_init(cmd[1]);
-				sreg = (1<<SREG_I);
-			}
 			else {
-				resp[2] = wdt_count;
+				int2frame(wdt_count, resp+1);
 				wdt_kick();
 			}
 			break;
@@ -527,34 +515,45 @@ void dac_ramp(unsigned int target)
 
 ISR(WDT_vect)
 {
-	toggle_hv_led();
 	if (wdt_count++ < conf.wdt_timeout)
-		goto wdt_out;
+		return;
-	hv_safe();
+	tick_init(conf.wdt_tick_period);
+	unsigned char mode = conf.wdt_mode;
+	conf.wdt_mode = WDT_MODE_RAMP;
+	do 
+		dac_ramp(conf.dac_off);
+	while (mode >= WDT_MODE_FULL && conf.dac != conf.dac_off);
 	wdt_reset();
+	if (conf.dac == conf.dac_off) {
+		if (conf.flags2 & FLAG2_PC_HV)
+			PORTC = conf.portc_off;
+		if (conf.flags2 & FLAG2_HVOSC)
+			hvosc_init(0, 0);
+	}
+	tick_init(conf.tick_period);
 	if (conf.wdt_save_addr && !wdt_saved) {
 		wdt_saved = 1;
 		eeprom_save(conf.wdt_save_addr);
 	}
-wdt_out:
+	WDTCSR |= WDIF; // should not be necessary 
-	WDTCSR |= WDIE;
 }
 
-void wdt_init(unsigned char mode)
+unsigned char wdt_init(unsigned char mode)
 {
 	conf.wdt_mode = mode;
 	wdt_reset();
 	if (mode < WDT_MODE_LIVE) {
 		WDTCSR = 0;
-		return;
+		return 0;
 	}
-	// 1s timeout, WDT interrupt enabled
+	// 8s timeout, WDT interrupt enabled
 	__asm__("STS %[CSR], %[CE]"     "\n\t"
 		"STS %[CSR], %[IE]"     "\n"
 		::[CSR] "n" (&WDTCSR),
-		 [CE] "r" ((unsigned char)(1<<WDCE | 1<<WDE | 1<<WDP2 | 1<<WDP1)),
+		 [CE] "r" ((unsigned char)(1<<WDCE | 1<<WDE | 1<<WDP3 | 1<<WDP0)),
-		 [IE] "r" ((unsigned char)(1<<WDIE | 1<<WDE | 1<<WDP2 | 1<<WDP1))
+		 [IE] "r" ((unsigned char)(1<<WDIE          | 1<<WDP3 | 1<<WDP0))
 		);
+	return 1 << SREG_I;
 }
 
 void eeprom_save(unsigned char a)

chaos/hvosc.h

@@ -18,9 +18,3 @@ static inline void hvosc_init(unsigned char freq, unsigned char dc)
 	OCR1BH = 0;
 	OCR1BL = freq-dc;
 }
-
-static inline
-int hvosc_is_on()
-{
-	return TCCR1A;
-}