Merge pull request #24 from emeb/master

Added polled ADC example

examples/adc_polled/Makefile

+TARGET:=adc_polled
+
+all : flash
+
+PREFIX:=riscv64-unknown-elf
+
+GPIO_Toggle:=EXAM/GPIO/GPIO_Toggle/User
+
+CH32V003FUN:=../../ch32v003fun
+MINICHLINK:=../../minichlink
+
+CFLAGS:= \
+	-g -Os -flto -ffunction-sections \
+	-static-libgcc -lgcc \
+	-march=rv32ec \
+	-mabi=ilp32e \
+	-I/usr/include/newlib \
+	-I$(CH32V003FUN) \
+	-nostdlib \
+	-I. -DSTDOUT_UART -Wall
+
+LDFLAGS:=-T $(CH32V003FUN)/ch32v003fun.ld -Wl,--gc-sections
+
+SYSTEM_C:=$(CH32V003FUN)/ch32v003fun.c
+
+$(TARGET).elf : $(SYSTEM_C) $(TARGET).c
+	$(PREFIX)-gcc -o $@ $^ $(CFLAGS) $(LDFLAGS)
+
+$(TARGET).bin : $(TARGET).elf
+	$(PREFIX)-size $^
+	$(PREFIX)-objdump -S $^ > $(TARGET).lst
+	$(PREFIX)-objdump -t $^ > $(TARGET).map
+	$(PREFIX)-objcopy -O binary $< $(TARGET).bin
+	$(PREFIX)-objcopy -O ihex $< $(TARGET).hex
+
+flash : $(TARGET).bin
+	$(MINICHLINK)/minichlink -w $< flash -b
+
+clean :
+	rm -rf $(TARGET).elf $(TARGET).bin $(TARGET).hex $(TARGET).lst $(TARGET).map $(TARGET).hex
+

examples/adc_polled/adc.h

+/*
+ * Single-File-Header for using ADC with polling
+ * 03-27-2023 E. Brombaugh
+ */
+
+#ifndef _ADC_H
+#define _ADC_H
+
+#include <stdint.h>
+
+/*
+ * initialize adc for polling
+ */
+void adc_init( void )
+{
+	// ADCCLK = 24 MHz => RCC_ADCPRE = 0: divide by 2
+	RCC->CFGR0 &= ~(0x1F<<11);
+	
+	// Enable GPIOD and ADC
+	RCC->APB2PCENR |= RCC_APB2Periph_GPIOD | RCC_APB2Periph_ADC1;
+	
+	// PD4 is analog input chl 7
+	GPIOD->CFGLR &= ~(0xf<<(4*4));	// CNF = 00: Analog, MODE = 00: Input
+	
+	// Reset the ADC to init all regs
+	RCC->APB2PRSTR |= RCC_APB2Periph_ADC1;
+	RCC->APB2PRSTR &= ~RCC_APB2Periph_ADC1;
+	
+	// Set up single conversion on chl 7
+	ADC1->RSQR1 = 0;
+	ADC1->RSQR2 = 0;
+	ADC1->RSQR3 = 7;	// 0-9 for 8 ext inputs and two internals
+	
+	// set sampling time for chl 7
+	ADC1->SAMPTR2 &= ~(ADC_SMP0<<(3*7));
+	ADC1->SAMPTR2 |= 7<<(3*7);	// 0:7 => 3/9/15/30/43/57/73/241 cycles
+		
+	// turn on ADC and set rule group to sw trig
+	ADC1->CTLR2 |= ADC_ADON | ADC_EXTSEL;
+	
+	// Reset calibration
+	ADC1->CTLR2 |= ADC_RSTCAL;
+	while(ADC1->CTLR2 & ADC_RSTCAL);
+	
+	// Calibrate
+	ADC1->CTLR2 |= ADC_CAL;
+	while(ADC1->CTLR2 & ADC_CAL);
+	
+	// should be ready for SW conversion now
+}
+
+/*
+ * start conversion, wait and return result
+ */
+uint16_t adc_get( void )
+{
+	// start sw conversion (auto clears)
+	ADC1->CTLR2 |= ADC_SWSTART;
+	
+	// wait for conversion complete
+	while(!(ADC1->STATR & ADC_EOC));
+	
+	// get result
+	return ADC1->RDATAR;
+}
+
+#endif

examples/adc_polled/adc_polled.c

+/*
+ * Example for using ADC with polling
+ * 03-27-2023 E. Brombaugh
+ */
+
+// Could be defined here, or in the processor defines.
+#define SYSTEM_CORE_CLOCK 48000000
+#define APB_CLOCK SYSTEM_CORE_CLOCK
+
+#include "ch32v003fun.h"
+#include <stdio.h>
+#include "adc.h"
+
+int main()
+{
+	uint32_t count = 0;
+	
+	SystemInit48HSI();
+
+	// start serial @ default 115200bps
+	SetupUART( UART_BRR );
+	printf("\r\r\n\nadc_polled example\n\r");
+
+	// init systick @ 1ms rate
+	printf("initializing adc...");
+	adc_init();
+	printf("done.\n\r");
+	
+	// Enable GPIOs
+	RCC->APB2PCENR |= RCC_APB2Periph_GPIOD;
+
+	// GPIO D0 Push-Pull
+	GPIOD->CFGLR &= ~(0xf<<(4*0));
+	GPIOD->CFGLR |= (GPIO_Speed_10MHz | GPIO_CNF_OUT_PP)<<(4*0);
+
+	printf("looping...\n\r");
+	while(1)
+	{
+		GPIOD->BSHR = 1;	 // Turn on GPIOs
+		Delay_Ms( 100 );
+		GPIOD->BSHR = (1<<16); // Turn off GPIODs
+		Delay_Ms( 100 );
+		printf( "Count: %lu adc: %d\n\r", count++, adc_get() );
+	}
+}