Merge pull request #125 from kabel42/input_capture

Input capture

examples/input_capture/Makefile

+all : flash
+
+TARGET:=input_capture
+
+include ../../ch32v003fun/ch32v003fun.mk
+
+flash : cv_flash
+clean : cv_clean
+
+

examples/input_capture/input_capture.c

+/* Small example showing how to capture timer values on gpio edges */
+
+#define SYSTEM_CORE_CLOCK 48000000
+
+#include "ch32v003fun.h"
+#include <stdio.h>
+
+#define APB_CLOCK SYSTEM_CORE_CLOCK
+
+#define queuelen 16
+volatile uint32_t captureVals[queuelen];
+volatile size_t read = 0;
+volatile size_t write = 0;
+
+void TIM1_CC_IRQHandler(void) __attribute__((interrupt));
+void TIM1_CC_IRQHandler(void)
+{
+	// capture
+	if(TIM1->INTFR & TIM_CC1IF)
+	{
+		// get capture
+		captureVals[write++] = 0x00010000 | TIM1->CH1CVR; // capture valur
+		if (write == queuelen)
+		{
+			write = 0;
+		}
+		// overflow
+		if(TIM1->INTFR & TIM_CC1OF)
+		{
+			// clear
+			TIM1->INTFR = ~(TIM_CC1OF); // cleard by writing 0
+			printf("OF1\n");
+		}
+	}
+	else if (TIM1->INTFR & TIM_CC2IF)
+	{
+		// get capture
+		captureVals[write++] = TIM1->CH2CVR; // capture valur
+		if (write == queuelen)
+		{
+			write = 0;
+		}
+		// overflow
+		if(TIM1->INTFR & TIM_CC2OF)
+		{
+			// clear
+			TIM1->INTFR = ~(TIM_CC2OF); // cleard by writing 0
+			printf("OF0\n");
+		}
+	}
+	else
+	{
+		printf("badtrigger\n");
+	}
+}
+
+int main()
+{
+	SystemInit48HSI();
+	SetupDebugPrintf();
+
+	Delay_Ms(100);
+
+	printf("UP\n");
+
+	// Enable peripherals
+	RCC->APB2PCENR = RCC_IOPDEN | RCC_TIM1EN;
+	RCC->APB2PRSTR = RCC_TIM1RST;
+	RCC->APB2PRSTR = 0;
+
+	// GPIO D0, D4 Push-Pull LEDs, D1/SWIO floating, D2 Capture Input(T1CH1), default analog input
+	GPIOD->CFGLR = ((GPIO_Speed_10MHz | GPIO_CNF_OUT_PP) << (4 * 0)) | 
+				   ((GPIO_SPEED_IN | GPIO_CNF_IN_FLOATING) << (4 * 1)) | 
+				   ((GPIO_SPEED_IN | GPIO_CNF_IN_FLOATING) << (4 * 2)) | 
+				   ((GPIO_Speed_10MHz | GPIO_CNF_OUT_PP) << (4 * 4));
+
+	TIM1->ATRLR = 0xffff;
+	TIM1->PSC = 47; // 48MHz/(47+1) -> 1µs resolution
+
+	TIM1->CHCTLR1 = TIM_CC1S_0 | TIM_CC2S_1;
+
+	TIM1->CCER = TIM_CC1E|TIM_CC2E|TIM_CC2P;
+
+	TIM1->CTLR1 = TIM_CEN;
+
+	NVIC_EnableIRQ(TIM1_CC_IRQn);
+	TIM1->DMAINTENR = TIM_CC1IE|TIM_CC2IE;
+
+	while (1)
+	{
+		if (read != write)
+		{
+			uint32_t val = captureVals[read++];
+			printf("capture %ld %lu\n", val >> 16, val & 0xFFFF);
+			if (read == queuelen)
+			{
+				read = 0;
+			}
+		}
+
+		// Turn D0 on and D4 off at the same time
+		GPIOD->BSHR = 1 | 1<<(16+4);
+		Delay_Ms(1);
+
+		// Turn D0 off and D4 on at the same time
+		GPIOD->BSHR = 1<<16 | 1<<4;
+		Delay_Ms(1);
+	}
+}
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