Initial prototype

This patch adds a skeleton of AVR code for a "simulator" target (atmega2560)
and for the real intended hardware target (atmega32u4). The simulator target
is one that is supported by the QEMU AVR emulator, while the 32u4 is currently
not.

1 files changed, 100 insertions, 0 deletions

diff --git a/altimeter.c b/altimeter.c
new file mode 100644
index 0000000..2aef956
--- /dev/null
+++ b/altimeter.c
@@ -0,0 +1,100 @@
+#include <math.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <avr/sleep.h>
+#include <avr/interrupt.h>
+
+#include "barometer.h"
+#include "display.h"
+#include "util.h"
+
+/* ISR for collecting and displaying pressure, altitude data etc */
+ISR(TIMER1_COMPA_vect)
+{
+	PORTD ^= 1 << 5;
+	int tcnt1_start = TCNT1;
+	static volatile float setting = 1040.21; /* FIXME volatile for gdb hacks */
+	static float last_height = 0;
+	float pressure = 0;
+	float height_m = 0;
+	float rate_m_s;
+	char rate_sym;
+	pressure = barometer_read();
+	height_m = pressure_to_metres_asl(pressure, setting);
+	rate_m_s = height_m - last_height;
+	last_height = height_m;
+
+	if (rate_m_s < 0) {
+		rate_sym = C_DESC;
+	} else if (rate_m_s == 0) {
+		rate_sym = C_IDLE;
+	} else {
+		rate_sym = C_ASC;
+	}
+
+	char line[LCD_WIDTH+1];
+	/* line 1 */
+	int alt_m_int;
+	float alt_m_float;
+	split_float(height_m, &alt_m_int, &alt_m_float);
+	snprintf(line, sizeof(line), "%d.%d m %c%d m/s", alt_m_int, (int)(round(alt_m_float*10)), rate_sym, abs(rate_m_s));
+	blank_to_eol(line, sizeof(line));
+	display_set_cursor(0, 0);
+	display_write(line);
+
+
+	/* line 2 */
+	int pressure_hpa_int;
+	float pressure_hpa_float;
+	split_float(pressure, &pressure_hpa_int, &pressure_hpa_float);
+	snprintf(line, sizeof(line), "%d.%d hPa", pressure_hpa_int, (int)(round(pressure_hpa_float*100)));
+	blank_to_eol(line, sizeof(line));
+	display_set_cursor(0, 1);
+	display_write(line);
+
+	/* line 3 */
+	int setting_hpa_int;
+	float setting_hpa_float;
+	split_float(setting, &setting_hpa_int, &setting_hpa_float);
+	snprintf(line, sizeof(line), "SET %d.%d hPa", setting_hpa_int, (int)(round(setting_hpa_float*100)));
+	blank_to_eol(line, sizeof(line));
+	display_set_cursor(0, 2);
+	display_write(line);
+
+	int tcnt1_end = TCNT1;
+	/* line 4 */
+	snprintf(line, sizeof(line), "TCNT1 delta %u", tcnt1_end - tcnt1_start);
+	blank_to_eol(line, sizeof(line));
+	display_set_cursor(0, 3);
+	display_write(line);
+	return;
+}
+
+int main(void)
+{
+	/* Initialise display before enabling interrupts */
+	display_init();
+	display_clear();
+
+	DDRB |= 1 << 0;
+	DDRD |= 1 << 5;
+
+	/* Initialise timers for /1024 prescaler, 1 Hz comparator val */
+	TCCR1B |= (1 << CS10) | (1 << CS12) | (1 << WGM12);
+	TIMSK1 |= (1 << OCIE1A);
+	OCR1A = 15624;
+
+#ifdef USBCON
+	/* Disable USB controller if one is present - this spams (latches?) USB_GEN
+	 * interrupt which we're not handling for now */
+	USBCON &= ~(1 << USBE);
+#endif
+
+	sei();
+	while(1) {
+		set_sleep_mode(SLEEP_MODE_IDLE);
+		sleep_mode();
+	}
+}