From be9ee9ed2d041c4ab4e77ee2010fe3c7a1ca6597 Mon Sep 17 00:00:00 2001
From: Keith Packard <keithp@keithp.com>
Date: Sat, 15 Jun 2013 01:20:49 -0700
Subject: [PATCH] altos/lpc: Filter ADC inputs

They're amazingly noisy on EasyMini, so just filter them as the only
thing we use them for is battery and pyro numbers.

Signed-off-by: Keith Packard <keithp@keithp.com>
---
 src/lpc/ao_adc_lpc.c    | 39 +++++++++++++++++++++++++--------------
 src/lpc/ao_arch_funcs.h |  6 ++----
 src/lpc/lpc.h           |  7 +++++++
 3 files changed, 34 insertions(+), 18 deletions(-)

diff --git a/src/lpc/ao_adc_lpc.c b/src/lpc/ao_adc_lpc.c
index 25a121b5..40173aa4 100644
--- a/src/lpc/ao_adc_lpc.c
+++ b/src/lpc/ao_adc_lpc.c
@@ -91,47 +91,58 @@
 			 (AO_ADC_6 << 6) |	\
 			 (AO_ADC_7 << 7))
 
-#define AO_ADC_CLKDIV	(AO_LPC_SYSCLK / 4500000 - 1)
+#define AO_ADC_CLKDIV	(AO_LPC_SYSCLK / 4500000)
 
-static uint8_t			ao_adc_ready;
+static uint8_t		ao_adc_ready;
+
+static uint16_t		ao_adc_prev[AO_NUM_ADC];
+
+#define sample(id)	do {				\
+		uint16_t	p = *prev;		\
+		uint16_t	v = lpc_adc.dr[id];	\
+		p -= p >> 4;				\
+		p += v >> 4;				\
+		*prev++ = p;				\
+		*out++ = p >> 1;			\
+	} while (0)
 
 void  lpc_adc_isr(void)
 {
 	uint32_t	stat = lpc_adc.stat;
 	uint16_t	*out;
+	uint16_t	*prev;
 
-	lpc_adc.cr = ((AO_ADC_MASK << LPC_ADC_CR_SEL) |
-		      (AO_ADC_CLKDIV << LPC_ADC_CR_CLKDIV) |
-		      (0 << LPC_ADC_CR_BURST) |
-		      (LPC_ADC_CR_CLKS_11 << LPC_ADC_CR_CLKS));
+	/* Turn off burst mode */
+	lpc_adc.cr = 0;
 	lpc_adc.stat = 0;
 
 	/* Store converted values in packet */
 
 	out = (uint16_t *) &ao_data_ring[ao_data_head].adc;
+	prev = ao_adc_prev;
 #if AO_ADC_0
-	*out++ = lpc_adc.dr[0] >> 1;
+	sample(0);
 #endif
 #if AO_ADC_1
-	*out++ = lpc_adc.dr[1] >> 1;
+	sample(1);
 #endif
 #if AO_ADC_2
-	*out++ = lpc_adc.dr[2] >> 1;
+	sample(2);
 #endif
 #if AO_ADC_3
-	*out++ = lpc_adc.dr[3] >> 1;
+	sample(3);
 #endif
 #if AO_ADC_4
-	*out++ = lpc_adc.dr[4] >> 1;
+	sample(4);
 #endif
 #if AO_ADC_5
-	*out++ = lpc_adc.dr[5] >> 1;
+	sample(5); 
 #endif
 #if AO_ADC_6
-	*out++ = lpc_adc.dr[6] >> 1;
+	sample(6);
 #endif
 #if AO_ADC_7
-	*out++ = lpc_adc.dr[7] >> 1;
+	sample(7);
 #endif
 
 	AO_DATA_PRESENT(AO_DATA_ADC);
diff --git a/src/lpc/ao_arch_funcs.h b/src/lpc/ao_arch_funcs.h
index 179b2f4d..1bbb14f5 100644
--- a/src/lpc/ao_arch_funcs.h
+++ b/src/lpc/ao_arch_funcs.h
@@ -61,12 +61,10 @@
 #define analog_func(id)			lpc_token_evaluator_2(LPC_IOCONF_FUNC_AD,id)
 
 #define ao_enable_analog(port,bit,id) do {				\
-		uint32_t _mode;						\
 		ao_enable_port(port);					\
 		lpc_gpio.dir[port] &= ~(1 << bit);			\
-		_mode = ((analog_func(id) << LPC_IOCONF_FUNC) |		\
-			 (0 << LPC_IOCONF_ADMODE));			\
-		lpc_ioconf.analog_reg(port,bit) = _mode;		\
+		lpc_ioconf.analog_reg(port,bit) = ((analog_func(id) << LPC_IOCONF_FUNC) | \
+						   (0 << LPC_IOCONF_ADMODE)); \
 	} while (0)
 	
 #define ARM_PUSH32(stack, val)	(*(--(stack)) = (val))
diff --git a/src/lpc/lpc.h b/src/lpc/lpc.h
index 49034c1c..d66f0dd0 100644
--- a/src/lpc/lpc.h
+++ b/src/lpc/lpc.h
@@ -1169,6 +1169,13 @@ extern struct lpc_adc lpc_adc;
 #define  LPC_ADC_CR_CLKS_6		5
 #define  LPC_ADC_CR_CLKS_5		6
 #define  LPC_ADC_CR_CLKS_4		7
+#define LPC_ADC_CR_START	24
+#define  LPC_ADC_CR_START_NONE		0
+#define  LPC_ADC_CR_START_NOW		1
+
+#define LPC_ADC_GDR_CHN			24
+#define LPC_ADC_GDR_OVERRUN		30
+#define LPC_ADC_GDR_DONE		31
 
 #define LPC_ADC_INTEN_ADINTEN	0
 #define LPC_ADC_INTEN_ADGINTEN	8
-- 
2.30.2