init m05e01

module05/ex01/Makefile

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+include ../../Makefile

module05/ex01/adc.c

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+#include "header.h"
+
+// Table 14-6. Port C Pins Alternate Functions
+// - PC0 -> ADC0 (ADC Input Channel 0)
+//       -> PCINT8 (Pin Change Interrupt 8)
+//
+// 24.2 : The ADC generates a 10-bit result which is presented in the ADC Data Registers, ADCH and ADCL
+//
+// START A CONVERSTION in single conversion mode :
+// - disabling the Power Reduction ADC bit, PRADC
+// - writing a logical one to the ADC Start Conversion bit, ADSC
+
+void adc_init(uint8_t prescaler_value) {
+    ADMUX = (1 << REFS0);								// Table 24-3 : set voltage reference, AVCC with external capacitor at AREF pin
+    ADCSRA = (1 << ADEN); 								// 24.9.2 : enable ADC
+    ADCSRA |= ADC_PRESCALE_SET(prescaler_value);		// Table 24-5 : prescaler ADC
+}
+
+uint16_t adc_read(uint8_t channel) {
+	CLEAR(PRR, PRADC);									// 24.3 : ensure power reduction is disabled for ADC, (10.11.3 : PRR – Power Reduction Register)
+    ADMUX = (ADMUX & 0b11110000) | (channel & 0b1111);	// Table 24-4 : Select ADC channel, (Table 14-6 : alternate function for RV1 on PC0 -> ADC0)
+    ADCSRA |= (1 << ADSC);								// 24.9.2 : Start conversion, ADSC: ADC Start Conversion
+    while (ADCSRA & (1 << ADSC));						// Wait for completion
+    return ADC;
+}

module05/ex01/header.h

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+#ifndef HEADER_H
+#define HEADER_H
+
+#include <avr/io.h>
+#include <util/delay.h>
+#include <avr/interrupt.h>
+
+#include "utils.h"
+#include "bitmanip.h"
+#include "interrupt.h"
+#include "timer.h"
+#include "usart.h"
+#include "adc.h"
+
+//
+// PROTOTYPES
+//
+// main.c
+void int_to_hex_string(uint64_t value, char *out, uint8_t num_digits);
+// adc.c
+void adc_init(uint8_t prescaler_value);
+uint16_t adc_read(uint8_t channel);
+// uart.c
+void uart_init();
+void uart_tx(char c);
+void uart_printstr(const char* str);
+void uart_printstr_endl(const char* str);
+
+//
+// MACROS
+//
+
+#endif // HEADER_H

module05/ex01/main.c

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+#include "header.h"
+
+// 1.1.7 : AVCC is the supply voltage pin for the A/D Converter, PC3:0, and ADC7:6
+// 1.1.8 : AREF is the analog reference pin for the A/D Converter
+
+#define ADC_PRESCALER	8
+
+void int_to_hex_string(uint64_t value, char *out, uint8_t num_digits) {				// num_digits : number of digit of the output, ex 2 for 3FF (1023) -> FF
+    for (uint8_t i = 0; i < num_digits; ++i) {
+        uint8_t shift = (num_digits - 1 - i) * 4;
+        out[i] = INT_TO_HEX_CHAR((value >> shift) & 0x0F);
+    }
+    out[num_digits] = '\0';
+}
+
+// description
+int main() {
+    char buffer[4];
+	SREG |= ENABLE_GLOBAL_INTERRUPT;												// 7.3.1 : Status Register, bit 7 : I – Global Interrupt Enable
+	uart_init();
+	adc_init(ADC_PRESCALER);
+
+	while(1) {
+        uint16_t value = adc_read(0);												// Read from ADC0 (A0)
+		int_to_hex_string(value, buffer, 3);
+        uart_printstr_endl(buffer);
+        _delay_ms(20);																// Wait 20ms
+	}
+}
+
+// ISR(ADC_vect) {		// Table 12-6 : interrupt vector for ADC Conversion Complete
+// }

module05/ex01/uart.c

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+#include "header.h"
+
+// MACROS
+// USART
+#define USART_BAUDRATE		115200
+#define INPUT_SIZE			7
+
+// GLOBAL VARIABLES
+
+//
+// FUNCTIONS
+//
+void uart_init() {
+	UBRR0H = (unsigned char) (BAUD_PRESCALER(USART_BAUDRATE) >> 8);					// 20.11.5 : UBRRnL and UBRRnH – USART Baud Rate Registers
+	UBRR0L = (unsigned char) BAUD_PRESCALER(USART_BAUDRATE);
+	UCSR0C = DATA_EIGHT_BIT;														// 20.11.4 : set Frame Format
+	UCSR0B = TRANSMITTER_ENABLED;													// 20.11.3 : enable Receiver, Transmitter, and interrupts
+}
+
+// char uart_rx(void) {
+// 	while (!TEST(UCSR0A, RXC0));												// 20.11.2 : do nothing until there are unread data in the receive buffer (UDRn), (RXCn flag in UCSRnA register set to 1 when buffer has data)
+// 	return UDR0;																	// 20.11.1 : get data in buffer, UDRn – USART I/O Data Register (read and write)
+// }
+
+void uart_tx(char c) {
+	while (!TEST(UCSR0A, UDRE0));												// 20.11.2 : do nothing until UDRn buffer is empty, (UDREn flag in UCSRnA register set to 1 when buffer empty)
+	UDR0 = (unsigned char) c;														// 20.11.1 : Put data into buffer, UDRn – USART I/O Data Register (read and write)
+}
+
+void uart_printstr(const char* str) {
+	while (*str) {
+		uart_tx(*str);
+		str++;
+	}
+}
+
+void uart_printstr_endl(const char* str) {
+	uart_printstr(str);
+	uart_printstr("\r\n");
+}
+
+// ISR(USART_RX_vect) {																// Table 12-6 : we select the code for USART Receive
+// 	char received_char = UDR0;														// read received character
+// 	if (received_char == '\b' || received_char == 127) {							// if backspace is received
+// 		if (input_index <= 0) {
+// 			return;
+// 		}
+// 		if (input_index >= INPUT_SIZE) {
+// 			return;
+// 		}
+// 		remove_last_character();
+// 		input_index--;
+// 		uart_tx('\b');  // Move cursor back
+// 		uart_tx(' ');   // Erase the character on screen
+// 		uart_tx('\b');  // Move cursor back again
+// 	} else if (received_char == '\n' || received_char == '\r') {					// if enter is received
+// 		if (input_index != INPUT_SIZE) {
+// 			return;
+// 		}
+// 		set_color((char *)color_input);
+// 		reset_input();
+// 	} else {																		// any other character
+// 		if (input_index >= INPUT_SIZE) {
+// 			return;
+// 		}
+// 		if (!is_valid_color_input(received_char)) {
+// 			return;
+// 		}
+// 		fill_str(received_char);
+// 		uart_tx(received_char);
+// 		input_index++;
+// 	}
+// }
+
+// ISR(USART_TX_vect) {																// Table 12-6 : we select the code for USART Transmit
+// 	char received_char = UDR0;														// read received character
+// }