POWER_LED and POWER_SYDBY

src/bate.c

@@ -410,7 +410,11 @@ int main()
 	sleep_enable();
 	sei();
 
-	send_str("\nV Turbo Weather V0.03\n");
+	uint8_t reset_source = RSTCTRL.RSTFR;
+	RSTCTRL.RSTFR = reset_source;
+	send_str("\nV Turbo Weather V0.04\nR ");
+	send_hex_byte(reset_source);
+	send_char('\n');
 
 	uint8_t test_calib = config.calib_test;
 	if (test_calib > N_TESTDATA)
@@ -467,11 +471,15 @@ int main()
 			}
 		}
 		if (!(trigger & config.triggers)) {
-			if (config.power & POWER_DOWN) {
+			if (config.power & (POWER_DOWN|POWER_STDBY)) {
 				mclk(0);
+				if (config.power & POWER_DOWN) {
 					if (config.power & POWER_DOWN_CLI)
 						cli();
 					set_sleep_mode(SLEEP_MODE_PWR_DOWN);
+				}
+				else
+					set_sleep_mode(SLEEP_MODE_STANDBY);
 				sleep_enable();
 				sleep_cpu();
 				set_sleep_mode(SLEEP_MODE_IDLE);
@@ -480,12 +488,12 @@ int main()
 		}
 
 		rfen(1);
+		if (config.power & POWER_LED)
 			led(1);
 
-		if (!mclk_status()) {
+		if (!mclk_status())
-			mclk(1);
 			mclk_delay = config.mclk_delay;
-		}
+		mclk(1);
 
 		if (!tick)
 			continue;
@@ -503,10 +511,10 @@ int main()
 		if (config.send & SEND_ADC)
 			start_adc();
 
+		if (config.send & SEND_CLOCK) {
 			cli();
 			uint32_t time = clock;
 			sei();
-		if (config.send & SEND_CLOCK) {
 			send_str("T 0x");
 			send_hex_long(time);
 			send_char('\n');

src/bate.h

@@ -36,6 +36,8 @@ enum power_flags {
 	POWER_DOWN        = 0x01,
 	POWER_DOWN_CLI    = 0x02,
 	STOP_MCLK         = 0x04,
+	POWER_LED         = 0x08,
+	POWER_STDBY       = 0x10,
 };
 enum send_flags {
 	SEND_CONFIG       = 0x01,

src/uart.c

@@ -56,6 +56,7 @@ uint8_t uart_tick()
 uint8_t uart_tx[128];
 volatile uint8_t uart_tx_w;
 volatile uint8_t uart_tx_r;
+volatile uint8_t uart_tx_b;
 static const uint8_t uart_tx_m = sizeof(uart_tx) - 1;
 
 static inline void tx()
@@ -65,6 +66,8 @@ static inline void tx()
 	while (r != uart_tx_w) {
 		if (!(USART0.STATUS & USART_DREIF_bm)) {
 			USART0.CTRLA |= USART_DREIE_bm;
+			USART0.STATUS = USART_TXCIF_bm;
+			uart_tx_b = USART_TXCIF_bm;
 			uart_tx_r = r;
 			return;
 		}
@@ -84,11 +87,20 @@ ISR(USART0_DRE_vect)
 __attribute__ ((noinline, noclone))
 uint8_t uart_busy()
 {
+	// How to test if we can power down?
+	// `uart_tx_b` is set to `TXC` when a char is loaded for transmission
+	// and the TXCIF is cleared.
+	// When `uart_tx_b` is zero, we are good,
+	// else when `TXCIF` is set we are also good.  
+	// When `uart_tx_b` is set but the `TXCIF` not yet, we are busy,
+	//returning TXC.
 	cli();
 	tx();
-	uint8_t r = uart_tx_w - uart_tx_r;
+	uint8_t b = uart_tx_b;
+	if (!b || USART0.STATUS & b)
+		b = uart_tx_b = 0;
 	sei();
-	return r;
+	return b;
 }
 
 __attribute__ ((noinline, noclone))