[136] | 1 | #include "delay.h"
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| 2 | #include "Arduino.h"
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| 3 |
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| 4 | #ifdef __cplusplus
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| 5 | extern "C" {
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| 6 | #endif
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| 7 |
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| 8 | /** Tick Counter united by ms */
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| 9 | static volatile uint32_t _ulTickCount=0 ;
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| 10 |
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| 11 | uint32_t millis( void )
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| 12 | {
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| 13 | // todo: ensure no interrupts
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| 14 | return _ulTickCount ;
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| 15 | }
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| 16 |
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| 17 | // Interrupt-compatible version of micros
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| 18 | // Theory: repeatedly take readings of SysTick counter, millis counter and SysTick interrupt pending flag.
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| 19 | // When it appears that millis counter and pending is stable and SysTick hasn't rolled over, use these
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| 20 | // values to calculate micros. If there is a pending SysTick, add one to the millis counter in the calculation.
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| 21 | uint32_t micros( void )
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| 22 | {
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| 23 | uint32_t ticks, ticks2;
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| 24 | uint32_t pend, pend2;
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| 25 | uint32_t count, count2;
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| 26 |
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| 27 | ticks2 = SysTick->VAL;
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| 28 | pend2 = !!(SCB->ICSR & SCB_ICSR_PENDSTSET_Msk) ;
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| 29 | count2 = _ulTickCount ;
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| 30 |
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| 31 | do
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| 32 | {
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| 33 | ticks=ticks2;
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| 34 | pend=pend2;
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| 35 | count=count2;
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| 36 | ticks2 = SysTick->VAL;
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| 37 | pend2 = !!(SCB->ICSR & SCB_ICSR_PENDSTSET_Msk) ;
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| 38 | count2 = _ulTickCount ;
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| 39 | } while ((pend != pend2) || (count != count2) || (ticks < ticks2));
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| 40 |
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| 41 | return ((count+pend) * 1000) + (((SysTick->LOAD - ticks)*(1048576/(VARIANT_MCK/1000000)))>>20) ;
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| 42 | // this is an optimization to turn a runtime division into two compile-time divisions and
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| 43 | // a runtime multiplication and shift, saving a few cycles
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| 44 | }
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| 45 |
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| 46 | void delay( uint32_t ms )
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| 47 | {
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| 48 | if ( ms == 0 )
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| 49 | {
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| 50 | return ;
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| 51 | }
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| 52 |
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| 53 | uint32_t start = _ulTickCount ;
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| 54 |
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| 55 | do
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| 56 | {
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| 57 | yield() ;
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| 58 | } while ( _ulTickCount - start <= (ms-1) ) ;
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| 59 | }
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| 60 |
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| 61 | void SysTick_Handler( void )
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| 62 | {
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| 63 | // Increment tick count each ms
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| 64 | _ulTickCount++ ;
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| 65 | }
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| 66 |
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| 67 | void delayMicroseconds(uint32_t usec)
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| 68 | {
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| 69 | unsigned int presc=0, ref=0, sot=1;
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| 70 | double ref_val=0.0, div_val=0.0, usec_val=0.0;
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| 71 | unsigned long int i=0,limit=0;
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| 72 |
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| 73 | if (usec <=0) return;
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| 74 | usec_val=usec * 1.0;
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| 75 |
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| 76 | if(usec <= 20)
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| 77 | {
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| 78 |
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| 79 |
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| 80 | if(usec == 1) limit = usec * 2;
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| 81 | else if(usec == 2) limit = usec * 6;
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| 82 | else if(usec == 3) limit = usec * 8;
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| 83 | else if(usec == 4) limit = usec * 9;
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| 84 | else if(usec == 5) limit = usec * 9;
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| 85 | else limit = usec * 11;
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| 86 |
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| 87 | for(i=0; i <= limit; i++);
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| 88 | {
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| 89 | asm("NOP");
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| 90 | }
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| 91 | return;
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| 92 | }
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| 93 | else if(usec <=1363)
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| 94 | {
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| 95 | presc=TC_CTRLA_PRESCALER_DIV1;
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| 96 | div_val=1.0;
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| 97 | ref = (uint16_t)(usec_val * 48.0 / div_val);
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| 98 | if((usec > 20) & (usec <=60)) ref= ref - 905;
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| 99 | if(usec > 60) ref= ref - 921;
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| 100 | }
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| 101 |
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| 102 | else if((usec > 1363) & (usec <= 5461))
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| 103 | {
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| 104 | presc=TC_CTRLA_PRESCALER_DIV4;
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| 105 | div_val=4.0;
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| 106 | ref = (uint16_t)(usec_val * 48.0 / div_val);
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| 107 |
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| 108 | }
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| 109 | else if((usec > 5461) & (usec <= 10922))
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| 110 | {
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| 111 | presc=TC_CTRLA_PRESCALER_DIV8;
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| 112 | div_val=8.0;
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| 113 | ref = (uint16_t)(usec_val * 48.0 / div_val);
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| 114 | }
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| 115 | else if((usec > 10922) & (usec <= 21845))
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| 116 | {
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| 117 | presc=TC_CTRLA_PRESCALER_DIV16;
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| 118 | div_val=16.0;
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| 119 | ref = (uint16_t)(usec_val * 48.0 / div_val);
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| 120 | }
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| 121 | else if(usec > 21845)
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| 122 | {
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| 123 | presc=TC_CTRLA_PRESCALER_DIV64;
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| 124 | div_val=64.0;
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| 125 | ref = (uint16_t)(usec_val * 48.0 / div_val);
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| 126 | }
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| 127 | else;
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| 128 |
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| 129 |
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| 130 | GCLK->CLKCTRL.reg = (uint16_t) (GCLK_CLKCTRL_CLKEN | GCLK_CLKCTRL_GEN_GCLK0 | GCLK_CLKCTRL_ID( GCM_TC4_TC5 ));
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| 131 |
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| 132 | TC4->COUNT16.CTRLA.reg &=~(TC_CTRLA_ENABLE);
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| 133 | TC4->COUNT16.CTRLA.reg |= TC_CTRLA_MODE_COUNT16 | presc;
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| 134 | TC4->COUNT16.READREQ.reg = 0x4002;
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| 135 | TC4->COUNT16.CTRLA.reg |= TC_CTRLA_ENABLE;
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| 136 |
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| 137 |
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| 138 | while(TC4->COUNT16.COUNT.reg < ref);
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| 139 |
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| 140 | return;
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| 141 | }
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| 142 |
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| 143 | #ifdef __cplusplus
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| 144 | }
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| 145 | #endif
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