From 273bb36d589d283b7bd1098fe699c92f97322cdf Mon Sep 17 00:00:00 2001
From: Jeff Epler <jepler@gmail.com>
Date: Mon, 25 Oct 2021 08:21:33 -0500
Subject: [PATCH] build for arduino

this, or something very close to it, did actually set the time once
but since then it stopped even synching to the wwvb pps.
---
 Makefile      | 31 ++++++++++++++++
 wwvbdecode.cc | 99 +++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 130 insertions(+)

diff --git a/Makefile b/Makefile
index d76f3e7..be97e69 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,36 @@
 CXX := g++
 CFLAGS := -Os -g -Wall
 
+MCU := atmega328
+AMCU := m328p
+AVRDUDE := avrdude -p${AMCU} -c arduino -P /dev/ttyUSB0 -b57600
+
+default: wwvbdecode wwvb.elf
+
+ifeq ($(shell [ -e /dev/ttyUSB0 ] && echo 1),1)
+default: program-stamp
+endif
+
+program-stamp: program
+	touch program-stamp
+
+program: wwvb.hex
+	${AVRDUDE} -q -q -D -U flash:w:$<:i
+	${AVRDUDE} -q -q -D -U eeprom:w:0x75,0x6e,0x73,0x65,0x74,0xd,0xa,0x0:m
+
+
 wwvbdecode: wwvbdecode.cc
 	$(CXX) $(CFLAGS) -o $@ $<
+
+AVR-CC := avr-gcc
+AVR-CFLAGS := -ffreestanding -funit-at-a-time -finline-functions-called-once \
+	-fno-exceptions -fno-rtti -mmcu=${MCU} -O3 -g
+
+wwvb.elf: wwvbdecode.cc
+	$(AVR-CC) $(AVR-CFLAGS) -o $@ $<
+	avr-size $@
+
+%.hex: %.elf
+	avr-objcopy -O ihex -R eeprom $< $@
+
+# vim:noet:ts=8:sts=8:sw=8
diff --git a/wwvbdecode.cc b/wwvbdecode.cc
index eff27c1..19332f6 100644
--- a/wwvbdecode.cc
+++ b/wwvbdecode.cc
@@ -384,5 +384,104 @@ int main() {
         wwvb_receive_loop(c == '1');
     }
     printf("failed to set time\n");
+}
+#else
+#include <stdio.h>
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#include <avr/eeprom.h>
+
+#define LED (5)
+#define WWVB (0)
+
+#define CYCLES_HIGH 16000
+
+int uptime;
+
+char buf[80];
+void set_time(const wwvb_t &t) {
+    snprintf(buf, sizeof(buf),
+        "set time %d/%03d %d:%02d:%02d ly=%d ls=%d dst=%d uptime=%d pol=%d\n",
+        t.year + 2000, t.yday, t.hour, t.minute, t.second, t.ls, t.ly, t.dst,
+        uptime, wwvb_polarity);
+    eeprom_write_block(buf, 0, strlen(buf)+1);
+
+    // set LED on solid
+    PORTB |= (1<<LED);
+
+    // and freeze here
+    while(1) {}
+}
+
+ISR(TIMER1_CAPT_vect) {
+    bool wwvb_raw = !!(PINB & (1<<WWVB));
+    wwvb_receive_loop(wwvb_raw);
+
+    int val;
+
+    if(wwvb_state == STATE_FIND_POLARITY) {
+        val = pps_good;
+    } else {
+        val = (wwvb_denoised ^ wwvb_polarity ) ? 1 : 16;
+    }
+    if((free_running_ms & 15) < val)
+        PORTB |= (1<<LED);
+    else
+        PORTB &= ~(1<<LED);
+}
+
+void eeprom_to_serial() {
+    uint8_t *i = 0;
+    uint8_t c;
+    while(i < (uint8_t*)256 && (c = eeprom_read_byte(i++))) {
+        while(!(UCSR0A & (1<<UDRE0)))
+            {}
+        UDR0 = c;
+    }
+}
+
+void next_second() {
+    uptime++;
+}
+
+void main() {
+    // Set up TIMER1 in CTC mode with ICR1 as top
+    TCCR1A = (1<WGM11);
+    TCCR1B = (1<<WGM13) | (1<<WGM12) | (1<<CS10);
+    ICR1 = CYCLES_HIGH;
+    TIMSK1 = (1<<ICIE1);
+
+    // Set the UART to 19.2kb/s.
+    #define F_CPU 16000000
+    #define BAUD 19200
+    #include <util/setbaud.h>
+    UBRR0H = UBRRH_VALUE;
+    UBRR0L = UBRRL_VALUE;
+    #if USE_2X
+    UCSR0A |= (1 << U2X0);
+    #else
+    UCSR0A &= ~(1 << U2X0);
+    #endif
+    DDRD = (1<<1); // enable TXD as output
+
+    // Set up the LED as output
+    DDRB = (1<<LED);
+
+    PORTB |= (1<<WWVB); // turn on pull-up on wwvb
+
+    // enable interrupts
+    sei();
+
+    // perhaps our predecessor left a message
+    eeprom_to_serial();
+
+    // and sleep forever, since things happen in the interrupt only
+#ifdef SLEEP_MODE_IDLE
+    set_sleep_mode(SLEEP_MODE_IDLE);
+    while(1) sleep_mode();
+#else
+    while(1) {}
+#endif
+
 }
 #endif