1 | /*------------------------------------------------------------
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2 | ATtiny402
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3 |
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4 | +3V --- VDD 1|‾‾‾‾‾‾‾|8 GND
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5 | PA6 2| |7 PA3 --- LED
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6 | PA7 3| |6 UPDI
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7 | piezo buzzer --- PA1 4|_______|5 PA2 --- piezo buzzer
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8 |
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9 | ---------------------------------------------------------------*/
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10 |
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11 | #include <avr/io.h>
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12 | #include <avr/interrupt.h>
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13 | #include <avr/sleep.h>
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14 |
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15 | volatile uint8_t pit; // SW PIT interrupt flag
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16 | uint8_t count; // SW counter
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17 | uint8_t cmpv = 180; // TCA CMP Value
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18 |
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19 | ISR(RTC_CNT_vect)
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20 | {
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21 | RTC.PITINTCTRL = RTC_PI_bm; // enable PIT interrupt
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22 | RTC.INTFLAGS = RTC_OVF_bm; // clear RTC OVF interrupt flag
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23 | }
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24 |
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25 | ISR(RTC_PIT_vect)
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26 | {
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27 | pit = 1; // set SW PIT interrupt flag
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28 | RTC.PITINTFLAGS = RTC_PI_bm; // clear PIT interrupt flag
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29 | }
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30 |
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31 | int main(void)
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32 | {
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33 | PORTA.PIN1CTRL = PORT_ISC_INPUT_DISABLE_gc; // disable digital input buffer
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34 | PORTA.PIN2CTRL = PORT_ISC_INPUT_DISABLE_gc; // disable digital input buffer
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35 | PORTA.PIN3CTRL = PORT_ISC_INPUT_DISABLE_gc; // disable digital input buffer
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36 | PORTA.PIN6CTRL = PORT_ISC_INPUT_DISABLE_gc; // disable digital input buffer
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37 | PORTA.PIN7CTRL = PORT_ISC_INPUT_DISABLE_gc; // disable digital input buffer
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38 |
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39 | PORTA.DIRSET = PIN3_bm; // PA3 output (LED)
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40 | PORTA.DIRSET = PIN1_bm; // PA1 output (TCA WO1)
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41 | PORTA.DIRSET = PIN2_bm; // PA2 output (TCA WO2)
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42 | PORTA.PIN2CTRL = PORT_INVEN_bm; // invert PA2 (TCA WO2, antiphase for piezo buzzer)
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43 |
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44 | RTC.CLKSEL = RTC_CLKSEL_INT1K_gc; // 1024 Hz from OSCULP32K
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45 | while (RTC.STATUS > 0) {} // wait for all register to be synchronized
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46 | RTC.PER = 0x0E0F; // RTC period (60 min @ 1Hz)
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47 | RTC.INTCTRL = RTC_OVF_bm; // enable RTC OVF interrupt
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48 | RTC.CTRLA = RTC_RUNSTDBY_bm | RTC_PRESCALER_DIV1024_gc | RTC_RTCEN_bm; // Run In Standby, 1Hz clock, enable RTC
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49 |
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50 | TCA0.SINGLE.CTRLB = TCA_SINGLE_CMP1EN_bm | TCA_SINGLE_CMP2EN_bm | TCA_SINGLE_WGMODE_SINGLESLOPE_gc; // enable compare channel 1 and 2, single-slope PWM
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51 | TCA0.SINGLE.CTRLA = TCA_SINGLE_CLKSEL_DIV2_gc | TCA_SINGLE_ENABLE_bm; // set clock source (1.666MHz), start TCA
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52 |
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53 | while (RTC.PITSTATUS > 0) {} // wait for RTC.PITCTRLA synchronization
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54 | RTC.PITCTRLA = RTC_PERIOD_CYC64_gc | RTC_PITEN_bm; // 62.5ms PIT time-out period, enable PIT
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55 | RTC.PITINTCTRL = RTC_PI_bm; // enable PIT interrupt
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56 |
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57 | SLPCTRL.CTRLA = SLPCTRL_SMODE_STDBY_gc; // select STANDBY sleep mode
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58 | sei(); // enable interrupts
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59 |
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60 | while(1)
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61 | {
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62 | PORTA.OUTSET = PIN3_bm; // PA3 on (LED on)
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63 | if(pit) // if PIT interrupt occurred
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64 | {
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65 | pit = 0; // clear SW PIT interrupt flag
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66 | TCA0.SINGLE.PERBUF = (cmpv << 2) - 1; // set period
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67 | TCA0.SINGLE.CMP1BUF = cmpv; // set compare match
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68 | TCA0.SINGLE.CMP2BUF = cmpv; // set compare match
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69 | cmpv = cmpv == 180 ? 190 : 180; // toggle between 180 and 190
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70 | count++;
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71 | if(count == 16)
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72 | {
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73 | count = 0; // clear SW counter
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74 | RTC.PITINTCTRL = 0; // disable PIT interrupt
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75 | PORTA.OUTCLR = PIN3_bm; // PA3 off (LED off)
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76 | sleep_mode();
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77 | }
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78 | }
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79 | }
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80 | }
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