bate: reduce standby current into pins

MCLK and DOUT randomly stick at high or low when the µC enters standby
mode.

MCLK TCA0 WO0 is properly disabled to keep the pin at low level.  A high
level pushes current into the pressure sensor.

DOUT input pullup is not enabled.  A low level on DOUT (LSB of the
temperature) pulls current from the pullup.

src/Makefile

@@ -126,7 +126,7 @@ BC_TRIG  = 0x29
 BC_SEND  = 0x59
 BC_PWR   = 0x7c
 BC_TEST  = 0
-BC_SPI   = 0xff
+BC_SPI   = 4
 BC_MDEL  = 2
 BC_PER   = 9
 BC_CPER  = 30
@@ -151,6 +151,8 @@ bate.config:
 clean:
 	rm -f *.hex *.o *.s *.map *.elf *.d
 
+bate.hex: bate.eeprom
+
 .PHONY: eeprom.eeprom
 eeprom.eeprom:
 	$(AD) -U eeprom:r:$@

src/bate.c

@@ -89,19 +89,48 @@ void rfen(uint8_t on)
 
 #define MCLK TCA0.SINGLE
 
+// The CMP0 port seems to be randomly high after TCA disable
+// The pin on the sensor draws  about 30µA when high.
+// Just toggling the ENABLE bit is insufficient.
+
+static inline
+void mclk(uint8_t on)
+{
+	if (on) {
+		MCLK.CTRLB = TCA_SINGLE_CMP0EN_bm | TCA_SINGLE_WGMODE_FRQ_gc;
+		MCLK.CTRLA = TCA_SINGLE_CLKSEL_DIV2_gc | TCA_SINGLE_ENABLE_bm;
+	}
+	else {
+		MCLK.CTRLA = 0;
+		MCLK.CTRLB = 0;
+	}
+}
+
 static inline
 void init_mclk(uint8_t p)
 {
-	if (p < 50 || p > 100)
+	if (!p || p==0xff)
 		p = PERIOD;
-	PORTB.DIRSET = Bit(0);
+	VPORTB.DIR |= Bit(0); // MCLK
 	MCLK.INTCTRL = TCA_SINGLE_CMP0_bm;
 	MCLK.CMP0 = p;
-	MCLK.CTRLA = TCA_SINGLE_CLKSEL_DIV2_gc;
-	MCLK.CTRLB = TCA_SINGLE_CMP0EN_bm | TCA_SINGLE_WGMODE_FRQ_gc;
+	mclk(1);
 	BATE_PORT.DIR |= Bit(DIN_PORT);
 	BATE_PORT.DIR |= Bit(SCK_PORT);
-	PORTA.PIN2CTRL = PORT_PULLUPEN_bm;
+
+	// DOUT input.
+	// The pullup draws 80µA in STDBY, when the sensor happens
+	// to end with DOUT=0.  The attached logic analyser drew 30µA,
+	// when DOUT=1 so the STDBY current was toggling between 50µA and 100µA.
+	// 20µA goes into the LDO.  Which we may want to remove.
+
+#   ifdef DOUT_PULLUP
+#       define PA2_PULLUP PORT_PULLUPEN_bm
+	PORTA.PIN2CTRL = PA2_PULLUP;
+#   else
+#       define PA2_PULLUP 0
+#   endif
+
 }
 
 ISR(PORTA_PORT_vect, ISR_NAKED)
@@ -137,7 +166,7 @@ void bate_wait()
 	uint16_t timeout = 3277; // 50ms
 	tick = 0;
 	while (BATE_PORT.IN & Bit(DOUT_PORT)) {
-		PORTA.PIN2CTRL = PORT_PULLUPEN_bm | PORT_ISC_FALLING_gc;
+		PORTA.PIN2CTRL = PA2_PULLUP | PORT_ISC_FALLING_gc;
 		sleep_cpu();
 		if (tick) {
 			tick = 0;
@@ -147,16 +176,7 @@ void bate_wait()
 			}
 		}
 	}
-	PORTA.PIN2CTRL = PORT_PULLUPEN_bm | PORT_ISC_INTDISABLE_gc;
-}
-
-static inline
-void mclk(uint8_t on)
-{
-	if (on)
-		MCLK.CTRLA |= TCA_SINGLE_ENABLE_bm;
-	else
-		MCLK.CTRLA &=~ TCA_SINGLE_ENABLE_bm;
+	PORTA.PIN2CTRL = PA2_PULLUP | PORT_ISC_INTDISABLE_gc;
 }
 
 static inline

src/calib.c

@@ -27,8 +27,8 @@ void bate_calib(const union bate *bate, struct pressure *pt)
 	uint16_t D1 = bate->D1;
 	uint16_t D2 = bate->D2;
 
-	uint16_t UT1  = C5 + 20224;
-	uint16_t  dT   = D2 - UT1;
+	uint16_t UT1 = C5 + 20224;
+	uint16_t  dT = D2 - UT1;
 
 	uint16_t TEMPSENS = C6 + 50;
 	int16_t  TEMP = mul16sun(dT, TEMPSENS, 6) + 200;
@@ -36,7 +36,7 @@ void bate_calib(const union bate *bate, struct pressure *pt)
 	int16_t  TCO = C4 - 512;
 	uint16_t OFFT1 = C2 << 2;
 	// fails when TCO < 0
-	uint16_t OFF  = OFFT1 + mul16sun(dT, TCO, 4);
+	uint16_t OFF = OFFT1 + mul16sun(dT, TCO, 4);
 
 	uint16_t SENST1 = C1 + 24576;
 	uint16_t TCS = C3;

src/mul.c

@@ -204,7 +204,7 @@ uint16_t divmod10(uint16_t u, uint8_t *mod)
 		"add   r20, r0"		"\n\t"
 		"adc   %A[r], r1"	"\n\t"
 		"adc   %B[r], r19"	"\n\t"
-		"ldi   r19, lo8(10)"	"\n\t"
+		"ldi   r19, 10"		"\n\t"
 		"inc   r20"		"\n\t"
 		"mul   r19, r20"	"\n\t"
 		"mov   %[d], r1"	"\n\t"