From 255085d06a75c424cd6b95aaac10056e5de65876 Mon Sep 17 00:00:00 2001
From: Daniel Friesel <derf@finalrewind.org>
Date: Fri, 19 Oct 2018 09:01:36 +0200
Subject: arduino nano: support additional CPU frequencies

---
 src/arch/arduino-nano-168/Makefile.inc | 29 +++++++++++++++++++++++++--
 src/arch/arduino-nano/Makefile.inc     | 10 ++++++++--
 src/arch/arduino-nano/arch.cc          | 36 +++++++++++++++++++++++++++++++++-
 src/arch/arduino-nano/driver/stdout.cc |  5 ++++-
 4 files changed, 74 insertions(+), 6 deletions(-)

(limited to 'src')

diff --git a/src/arch/arduino-nano-168/Makefile.inc b/src/arch/arduino-nano-168/Makefile.inc
index 534ac27..a56e62a 100644
--- a/src/arch/arduino-nano-168/Makefile.inc
+++ b/src/arch/arduino-nano-168/Makefile.inc
@@ -7,7 +7,8 @@ BAUD = 19200
 cpu_freq ?= 16000000
 
 COMMON_FLAGS += -Werror=overflow
-COMMON_FLAGS += -mmcu=${MCU} -DF_CPU=16000000UL -DMULTIPASS_ARCH_arduino_nano
+COMMON_FLAGS += -mmcu=${MCU} -DMULTIPASS_ARCH_arduino_nano
+COMMON_FLAGS += -DF_CPU=${cpu_freq}UL
 COMMON_FLAGS += -flto
 COMMON_FLAGS += -DMULTIPASS_ARCH_HAS_I2C
 
@@ -39,6 +40,30 @@ ifneq ($(findstring timer,${arch_drivers}), )
 	TARGETS += src/arch/arduino-nano/driver/timer.cc
 endif
 
+ifeq (${cpu_freq}, 16000000)
+	uart_baud = 57600
+else ifeq (${cpu_freq}, 8000000)
+	uart_baud = 38400
+else ifeq (${cpu_freq}, 4000000)
+	uart_baud = 38400
+else ifeq (${cpu_freq}, 2000000)
+	uart_baud = 19200
+else ifeq (${cpu_freq}, 1000000)
+	uart_baud = 9600
+else ifeq (${cpu_freq}, 500000)
+	uart_baud = 4800
+else ifeq (${cpu_freq}, 250000)
+	uart_baud = 2400
+else ifeq (${cpu_freq}, 125000)
+	uart_baud = 1200
+else ifeq (${cpu_freq}, 62500)
+	uart_baud = 300
+else
+	uart_baud = 9600
+endif
+
+COMMON_FLAGS += -DBAUD=${uart_baud}UL
+
 OBJECTS = ${TARGETS:.cc=.o}
 
 .cc.o:
@@ -58,7 +83,7 @@ arch_clean:
 	${QUIET}rm -f ${OBJECTS} build/system.hex
 
 monitor:
-	${QUIET}screen ${PORT} 115200
+	${QUIET}screen ${PORT} ${uart_baud}
 
 arch_help:
 	@echo "arduino-nano specific flags:"
diff --git a/src/arch/arduino-nano/Makefile.inc b/src/arch/arduino-nano/Makefile.inc
index bb51b6c..08dd6c1 100644
--- a/src/arch/arduino-nano/Makefile.inc
+++ b/src/arch/arduino-nano/Makefile.inc
@@ -7,7 +7,7 @@ BAUD = 57600
 cpu_freq ?= 16000000
 
 COMMON_FLAGS += -Werror=overflow
-COMMON_FLAGS += -mmcu=${MCU} -DF_CPU=16000000UL -DMULTIPASS_ARCH_arduino_nano
+COMMON_FLAGS += -mmcu=${MCU} -DMULTIPASS_ARCH_arduino_nano
 COMMON_FLAGS += -flto
 COMMON_FLAGS += -DMULTIPASS_ARCH_HAS_I2C
 
@@ -39,6 +39,12 @@ ifneq ($(findstring timer,${arch_drivers}), )
 	TARGETS += src/arch/arduino-nano/driver/timer.cc
 endif
 
+ifneq (${cpu_freq}, )
+	COMMON_FLAGS += -DF_CPU=${cpu_freq}UL
+else
+	COMMON_FLAGS += -DF_CPU=16000000UL
+endif
+
 OBJECTS = ${TARGETS:.cc=.o}
 
 .cc.o:
@@ -58,7 +64,7 @@ arch_clean:
 	${QUIET}rm -f ${OBJECTS} build/system.hex
 
 monitor:
-	${QUIET}screen ${PORT} 115200
+	${QUIET}screen ${PORT} 19200
 
 arch_help:
 	@echo "arduino-nano specific flags:"
diff --git a/src/arch/arduino-nano/arch.cc b/src/arch/arduino-nano/arch.cc
index b034348..2d957fc 100644
--- a/src/arch/arduino-nano/arch.cc
+++ b/src/arch/arduino-nano/arch.cc
@@ -5,6 +5,37 @@
 
 void Arch::setup(void)
 {
+
+#if F_CPU == 16000000UL
+	/* default */
+#elif F_CPU == 8000000UL
+	CLKPR = _BV(CLKPCE);
+	CLKPR = _BV(CLKPS0);
+#elif F_CPU == 4000000UL
+	CLKPR = _BV(CLKPCE);
+	CLKPR = _BV(CLKPS1);
+#elif F_CPU == 2000000UL
+	CLKPR = _BV(CLKPCE);
+	CLKPR = _BV(CLKPS1) | _BV(CLKPS0);
+#elif F_CPU == 1000000UL
+	CLKPR = _BV(CLKPCE);
+	CLKPR = _BV(CLKPS2);
+#elif F_CPU == 500000UL
+	CLKPR = _BV(CLKPCE);
+	CLKPR = _BV(CLKPS2) | _BV(CLKPS0);
+#elif F_CPU == 250000UL
+	CLKPR = _BV(CLKPCE);
+	CLKPR = _BV(CLKPS2) | _BV(CLKPS1);
+#elif F_CPU == 125000UL
+	CLKPR = _BV(CLKPCE);
+	CLKPR = _BV(CLKPS2) | _BV(CLKPS1) | _BV(CLKPS0);
+#elif F_CPU == 62500UL
+	CLKPR = _BV(CLKPCE);
+	CLKPR = _BV(CLKPS3);
+#else
+#error Unsupported F_CPU
+#endif
+
 #ifdef TIMER_CYCLES
 	TCCR0A = 0;
 	TCCR0B = _BV(CS00);
@@ -13,11 +44,14 @@ void Arch::setup(void)
 #if defined(WITH_LOOP) || defined(TIMER_S)
 	TCCR1A = 0;
 	TCCR1B = _BV(WGM12) | _BV(CS12) | _BV(CS10); // /1024
-	OCR1A = 15625;
+	OCR1A = F_CPU / 1024;
 	TIMSK1 = _BV(OCIE1A);
 #endif
 
 #ifdef TIMER_US
+#if F_CPU != 16000000UL
+#error TIMER_US is only supported with F_CPU = 16MHz
+#endif
 	// 16MHz/8 -> 2MHz timer
 	TCCR2A = 0;
 	TCCR2B = _BV(CS21);
diff --git a/src/arch/arduino-nano/driver/stdout.cc b/src/arch/arduino-nano/driver/stdout.cc
index a3d905d..58ff440 100644
--- a/src/arch/arduino-nano/driver/stdout.cc
+++ b/src/arch/arduino-nano/driver/stdout.cc
@@ -2,7 +2,10 @@
 #include <avr/io.h>
 #include <avr/interrupt.h>
 
-#define BAUD 119200L
+#ifndef BAUD
+#define BAUD 9600UL
+#endif
+
 #include <util/setbaud.h>
 
 void StandardOutput::setup()
-- 
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