From de23a47009bb301518417d097b3360253a01c635 Mon Sep 17 00:00:00 2001
From: Daniel Friesel <derf@finalrewind.org>
Date: Wed, 18 Mar 2020 22:01:06 +0100
Subject: Arduino: Add ADC driver

---
 include/arch/arduino-nano/driver/adc.h | 17 ++++++++
 src/arch/arduino-nano-168/Makefile.inc |  8 ++++
 src/arch/arduino-nano/Makefile.inc     |  4 ++
 src/arch/arduino-nano/driver/adc.cc    | 76 ++++++++++++++++++++++++++++++++++
 4 files changed, 105 insertions(+)
 create mode 100644 include/arch/arduino-nano/driver/adc.h
 create mode 100644 src/arch/arduino-nano/driver/adc.cc

diff --git a/include/arch/arduino-nano/driver/adc.h b/include/arch/arduino-nano/driver/adc.h
new file mode 100644
index 0000000..4af64b8
--- /dev/null
+++ b/include/arch/arduino-nano/driver/adc.h
@@ -0,0 +1,17 @@
+#ifndef ADC_H
+#define ADC_H
+
+class AVRADC {
+	private:
+		AVRADC(AVRADC const &copy);
+
+	public:
+		AVRADC() {}
+
+		int16_t getTemp_mdegC(int16_t offset = 205);
+		uint16_t getVCC_mV();
+};
+
+extern AVRADC adc;
+
+#endif
diff --git a/src/arch/arduino-nano-168/Makefile.inc b/src/arch/arduino-nano-168/Makefile.inc
index f57914e..70392e1 100644
--- a/src/arch/arduino-nano-168/Makefile.inc
+++ b/src/arch/arduino-nano-168/Makefile.inc
@@ -37,6 +37,10 @@ else ifneq ($(findstring i2c,${arch_drivers}), )
 	CXX_TARGETS += src/arch/arduino-nano/driver/i2c.cc
 endif
 
+ifneq ($(findstring adc,${arch_drivers}), )
+	CXX_TARGETS += src/arch/arduino-nano/driver/adc.cc
+endif
+
 ifneq ($(findstring spi,${arch_drivers}), )
 	CXX_TARGETS += src/arch/arduino-nano/driver/spi.cc
 endif
@@ -53,6 +57,10 @@ ifneq ($(findstring counter,${arch_drivers}), )
 	CXX_TARGETS += src/arch/arduino-nano/driver/counter.cc
 endif
 
+ifneq ($(findstring neopixel,${arch_drivers}), )
+	CXX_TARGETS += src/arch/arduino-nano/driver/neopixel.cc
+endif
+
 ifeq (${cpu_freq}, 16000000)
 	uart_baud = 57600
 else ifeq (${cpu_freq}, 8000000)
diff --git a/src/arch/arduino-nano/Makefile.inc b/src/arch/arduino-nano/Makefile.inc
index ebc77ea..a664a30 100644
--- a/src/arch/arduino-nano/Makefile.inc
+++ b/src/arch/arduino-nano/Makefile.inc
@@ -37,6 +37,10 @@ else ifneq ($(findstring i2c,${arch_drivers}), )
 	CXX_TARGETS += src/arch/arduino-nano/driver/i2c.cc
 endif
 
+ifneq ($(findstring adc,${arch_drivers}), )
+	CXX_TARGETS += src/arch/arduino-nano/driver/adc.cc
+endif
+
 ifneq ($(findstring spi,${arch_drivers}), )
 	CXX_TARGETS += src/arch/arduino-nano/driver/spi.cc
 endif
diff --git a/src/arch/arduino-nano/driver/adc.cc b/src/arch/arduino-nano/driver/adc.cc
new file mode 100644
index 0000000..1583b15
--- /dev/null
+++ b/src/arch/arduino-nano/driver/adc.cc
@@ -0,0 +1,76 @@
+#include <avr/io.h>
+
+#include "arch.h"
+#include "driver/adc.h"
+
+int16_t AVRADC::getTemp_mdegC(int16_t offset)
+{
+	// Measure temperature probe with 1.1V bandgap reference
+	ADMUX = _BV(REFS1) |  _BV(REFS0) | 0x08;
+
+	// Enable ADC with /64 prescaler
+	ADCSRA = _BV(ADEN) | _BV(ADPS2);
+
+	// Wait for bandgap to stabilise (70us according to datasheet table 28-3)
+	arch.delay_ms(1);
+
+	// Start conversion
+	ADCSRA |= _BV(ADSC);
+
+	// Wait for conversion to complete
+	while (ADCSRA & _BV(ADSC)) ;
+
+	// typical values: 242 mV @ -45 degC
+	// typical values: 314 mV @ +25 degC
+	// typical values: 380 mV @ +85 degC
+	// slope: 0.9090.. degC / mV at  25 .. 85 degC
+	// -> approx. 286.5 mV @ 0 degC / approx -260.45 degC @ 0 mV
+	// -> T[degC] = ADC[mV] * 0.91 - 261
+	// -> T[mdegC] = ADC[mV] * 91 - 26100
+	// slope: 0.9722.. mV / degC at -45 .. 25 degC
+	// slope: 0.942    mV / degC at -45 .. 85 degC
+	uint8_t adcr_l = ADCL;
+	uint8_t adcr_h = ADCH;
+	uint16_t adcr = adcr_l + (adcr_h << 8);
+	uint16_t vadc = 1100L * adcr / 1023L;
+
+	// adjust for chip-specific variations
+	vadc += offset;
+
+	int16_t temp_mdegc = vadc * 91 - 26100L;
+
+	// Disable ADC
+	ADCSRA &= ~_BV(ADEN);
+
+	return temp_mdegc;
+}
+
+uint16_t AVRADC::getVCC_mV()
+{
+	// Measure internal 1.1V bandgap using VCC as reference
+	ADMUX = _BV(REFS0) | 0x0e;
+
+	// Enable ADC with /64 prescaler
+	ADCSRA = _BV(ADEN) | _BV(ADPS2);
+
+	// Wait for bandgap to stabilise (70us according to datasheet table 28-3)
+	arch.delay_ms(1);
+
+	// Start conversion
+	ADCSRA |= _BV(ADSC);
+
+	// Wait for conversion to complete
+	while (ADCSRA & _BV(ADSC)) ;
+
+	uint8_t adcr_l = ADCL;
+	uint8_t adcr_h = ADCH;
+	uint16_t adcr = adcr_l + (adcr_h << 8);
+	uint16_t vcc = 1100L * 1023 / adcr;
+
+	// Disable ADC
+	ADCSRA &= ~_BV(ADEN);
+
+	return vcc;
+}
+
+AVRADC adc;
-- 
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