88 lines
2.6 KiB
C
88 lines
2.6 KiB
C
#include <avr/io.h>
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// stringify
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#define STRINGIFY_HELPER(x) #x
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#define STRINGIFY(x) STRINGIFY_HELPER(x)
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// concatenate
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#define CONCAT_HELPER(x, y) x ## y
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#define CONCAT(x, y) CONCAT_HELPER(x, y)
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// get argument
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#define ARG_1(v1, v2) v1
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#define ARG_2(v1, v2) v2
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#define GET_PORT(args) ARG_1 args
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#define GET_BIT(args) ARG_2 args
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// actions on registers
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#define SET(register, bit) register |= 1 << bit
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#define CLEAR(register, bit) register &= ~(1 << bit)
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#define TEST(register, bit) register & 1 << bit
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#define TOGGLE(register, bit) register ^= 1 << bit
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// actions on elements
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#define SET_ELEM(elem) SET(CONCAT(PORT, GET_PORT(elem)), GET_BIT(elem))
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#define CLEAR_ELEM(elem) CLEAR(CONCAT(PORT, GET_PORT(elem)), GET_BIT(elem))
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#define TEST_ELEM(elem) TEST(CONCAT(PORT, GET_PORT(elem)), GET_BIT(elem))
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#define TOGGLE_ELEM(elem) TOGGLE(CONCAT(PORT, GET_PORT(elem)), GET_BIT(elem))
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#define MODE_OUTPUT(elem) SET(CONCAT(DDR, GET_PORT(elem)), GET_BIT(elem))
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#define MODE_INPUT(elem) CLEAR(CONCAT(DDR, GET_PORT(elem)), GET_BIT(elem))
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#define TOGGLE_PIN(elem) SET(CONCAT(PIN, GET_PORT(elem)), GET_BIT(elem))
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#define TEST_PIN(elem) (TEST(CONCAT(PIN, GET_PORT(elem)), GET_BIT(elem)))
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#define IS_PIN_SET(elem) (TEST_PIN(elem) == 0)
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#define IS_PIN_CLEAR(elem) (TEST_PIN(elem) == 1)
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// bits
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#define D1 0
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#define D2 1
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#define D3 2
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#define D4 4
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#define SW1 2
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#define SW2 4
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// elements (port, bit)
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#define LED1 (B, D1)
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#define LED2 (B, D2)
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#define LED3 (B, D3)
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#define LED4 (B, D4)
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#define BUTTON1 (D, SW1)
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#define BUTTON2 (D, SW2)
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// TIME
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#define PRESCALE_VALUE 1024
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#if (PRESCALE_VALUE == 1)
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#define PRESCALE_SET (1 << CS10)
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#elif (PRESCALE_VALUE == 8)
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#define PRESCALE_SET (1 << CS11)
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#elif (PRESCALE_VALUE == 64)
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#define PRESCALE_SET (1 << CS10) | (1 << CS11)
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#elif (PRESCALE_VALUE == 256)
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#define PRESCALE_SET (1 << CS12)
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#elif (PRESCALE_VALUE == 1024)
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#define PRESCALE_SET (1 << CS10) | (1 << CS12)
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#endif
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#define TIME_MS(ms) (((F_CPU / PRESCALE_VALUE) * ms) / 1000)
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#define PERIOD 500
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// END MACROS
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// led turns on and off every PERIOD ms
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int main() {
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MODE_OUTPUT(LED2);
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TCCR1B |= (1 << WGM12); // Table 16-4 : set timer in CTC (Clear Time on Compare) mode, use bit WGM12, located in register TCCR1B (16.11.2)
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TCCR1A |= (1 << COM1A0); // 14.3.1 : set Compare Output with COM1A0, it toggles OC1A on compare match (Table 16-1), OC1A is alternate function for PORTB1 (Table 14-3)
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OCR1A = TIME_MS(PERIOD); // Table 16-4 : set CTC compare value, the counter is cleared to zero when the counter value (TCNT1) matches the OCR1A register
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TCCR1B |= (PRESCALE_SET);
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while(1);
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}
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