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authorMatthias P. Braendli <matthias.braendli@mpb.li>2019-10-19 10:01:46 +0200
committerMatthias P. Braendli <matthias.braendli@mpb.li>2019-10-19 10:01:46 +0200
commitc5125401789c03536453c3f8d00e463a012fa1dd (patch)
tree7e9e2da8c54977b2066e7e0981c4a13d3dbd19db /sw/main.cpp
parent6e1a23473db7b35f4da8c85fa282aa3f872e70b0 (diff)
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Add timer initialisation
Diffstat (limited to 'sw/main.cpp')
-rw-r--r--sw/main.cpp87
1 files changed, 87 insertions, 0 deletions
diff --git a/sw/main.cpp b/sw/main.cpp
index a021b96..1f053d0 100644
--- a/sw/main.cpp
+++ b/sw/main.cpp
@@ -28,9 +28,96 @@
#include <avr/pgmspace.h>
#include <avr/io.h>
#include <avr/interrupt.h>
+#include <avr/sleep.h>
+
+// Definitions allocation pin
+#define PIN(x) (1 << x)
+
+/* ALL relay signals PINx_Kx have external pulldown.
+ * All pins whose name ends in 'n' are active low */
+
+// PORT B
+constexpr uint8_t PINB_STATUSn = PIN(0);
+// Pins 2,3,4,5 = SPI
+constexpr uint8_t PINB_SPI_LTC_CSn = PIN(2); // with external pullup
+constexpr uint8_t PINB_SPI_MOSI = PIN(3);
+constexpr uint8_t PINB_SPI_MISO = PIN(4);
+constexpr uint8_t PINB_SPI_SCK = PIN(5);
+
+constexpr uint8_t PINB_OUTPUTS =
+ PINB_STATUSn | PINB_SPI_SCK | PINB_SPI_MOSI | PINB_SPI_LTC_CSn;
+
+// PORT C
+constexpr uint8_t PINC_ADC0 = PIN(0);
+constexpr uint8_t PINC_ADC1 = PIN(1);
+constexpr uint8_t PINC_K3_RESET = PIN(2);
+constexpr uint8_t PINC_K3_SET = PIN(3);
+constexpr uint8_t PINC_K2_RESET = PIN(4);
+constexpr uint8_t PINC_K2_SET = PIN(5);
+
+constexpr uint8_t PINC_OUTPUTS =
+ PINC_K3_RESET | PINC_K3_SET |
+ PINC_K2_RESET | PINC_K2_SET;
+
+// PORT D
+// Pins 0,1 = UART RX,TX
+constexpr uint8_t PIND_UART_RX = PIN(0);
+constexpr uint8_t PIND_UART_TX = PIN(1);
+
+constexpr uint8_t PIND_ONEWIRE = PIN(4); // with exteral pullup
+
+constexpr uint8_t PIND_K1_RESET = PIN(5);
+constexpr uint8_t PIND_K1_SET = PIN(6);
+
+constexpr uint8_t PIND_OUTPUTS =
+ PIND_UART_TX |
+ PIND_K1_RESET | PIND_K1_SET;
+
+
+/* Assuming F_CPU at 16MHz / 8:
+ *
+ * overflow for 100ms: F_CPU [ticks/s] / prescaler [unit-less] * interval [s] = [ticks/s*s] = [ticks]
+ * interval [s] = 0.1 = 1 / 10
+ *
+ * Actual interval after rounding:
+ * interval [s] = overflow [ticks] / (F_CPU [ticks/s] / prescaler [unit-less])
+ * = 99.84 ms
+ */
+volatile uint8_t timer_counter; /* Timer */
+
+ISR(TIMER0_COMPA_vect)
+{
+ timer_counter++;
+}
int main()
{
+ /* Setup GPIO */
+ // Active-low outputs must be high
+ PORTB = PINB_STATUSn | PINB_SPI_LTC_CSn;
+ PORTC = 0;
+ PORTD = 0;
+
+ // Enable output
+ DDRB = PINB_OUTPUTS;
+ DDRC = PINC_OUTPUTS;
+ DDRD = PIND_OUTPUTS;
+
+ /* Setup 100Hz timer */
+ TCCR0B |= (1 << WGM02); // Set timer mode to CTC (datasheet 15.7.2)
+ TIMSK0 |= (1 << TOIE0); // enable overflow interrupt
+ OCR0A = (uint8_t)(F_CPU / 1024 / 10); // Overflow at 99.84 ms
+ TCCR0B |= (1 << CS02) | (1 << CS00); // Start timer at Fcpu/1024
+
+ /* Enable interrupts */
+ sei();
+
+ /* Put the CPU to sleep */
+ set_sleep_mode(SLEEP_MODE_IDLE);
+ sleep_enable();
+ while (true) {
+ sleep_cpu();
+ }
return 0;
}