init module06

module06/ex00/Makefile

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+include ../../Makefile

module06/ex00/adc.c

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+#include "header.h"
+
+// 24.2 : The ADC generates a 10-bit result which is presented in the ADC Data Registers, ADCH and ADCL
+
+void adc_init(uint8_t prescaler_value) {
+    ADMUX = (1 << REFS0);									// Table 24-3 : set voltage reference, AVCC with external capacitor at AREF pin
+	ADMUX |= (1 << ADLAR);									// 24.9.1 : result is left adjusted, meaning the first 8 bits values are readable in ADCH, (24.9.3.2 : ADC data register is not updated util ADCH is read)
+    ADCSRA = (1 << ADEN); 									// 24.9.2 : enable ADC
+	ADCSRA |= (1 << ADATE); 								// 24.9.2 : enable Auto Trigger -> it will start a conversion on the selected channel in ADMUX when the selected source (in ADCSRB) is triggered
+	ADCSRA |= (1 << ADIE);								 	// 24.9.2 : enable ADC Interrupt
+    ADCSRA |= ADC_PRESCALE_SET(prescaler_value);			// Table 24-5 : prescaler ADC
+
+	ADCSRB = ADC_TRIGGER_TIMER_1_COMPARE_B;					// Table 24-6 : ADC Auto Trigger Source
+	ADMUX = (ADMUX & 0b11110000) | (adc_channel & 0b1111);	// Table 24-4 : Select ADC channel 0, (Table 14-6 : alternate function for RV1 on PC0 -> ADC0)
+}
+
+
+void adc_print_hex(uint8_t value) {
+	char buffer[3] = {0};
+	int_to_hex_string(value, buffer, 2);
+	uart_printstr_endl(buffer);
+}
+
+ISR(ADC_vect) {												// Table 12-6 : interrupt vector for ADC Conversion Complete
+	uint8_t value = ADCH;									// 24.9.3.2 : read ADCH 8 bits precision
+	adc_print_hex(value);
+}

module06/ex00/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"
+
+//
+// GLOBAL
+//
+extern volatile uint8_t adc_channel;
+
+//
+// PROTOTYPES
+//
+// main.c
+// timer.c
+void timer_1B_init();
+// math.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

module06/ex00/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
+// 24.4 : frequency needs to be between 50kHz and 200kHz, for less than 10bits accuracy it can be >200kHz
+//  -> Frequence_ADC = Frequance_CPU / Prescaler (Fadc = Fcpu/P):
+//     - P = 2   -> Fadc = 16,000,000 / 2   = 8,000,000 = 8MHz
+//     - P = 4   -> Fadc = 16,000,000 / 4   = 4,000,000 = 4MHz
+//     - P = 8   -> Fadc = 16,000,000 / 8   = 2,000,000 = 2MHz
+//     - P = 16  -> Fadc = 16,000,000 / 16  = 1,000,000 = 1MHz
+//     - P = 32  -> Fadc = 16,000,000 / 32  =   500,000 = 500KHz
+//     - P = 64  -> Fadc = 16,000,000 / 64  =   250,000 = 250KHz -> OK
+//     - P = 128 -> Fadc = 16,000,000 / 128 =   125,000 = 125KHz -> OK
+
+#define ADC_PRESCALER	64														// Table 24-5 : can only be 2, 4, 8, 16, 32, 64, or 128
+
+volatile uint8_t adc_channel = 0;
+
+// read potentiometer value and print it in uart as hexadecimal 2-number
+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);
+
+	timer_1B_init();
+
+	while(1);
+}

module06/ex00/math.c

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+#include "header.h"
+
+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';
+}

module06/ex00/timer.c

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+#include "header.h"
+
+// Set up Timer1 in CTC mode to trigger every 20ms
+// With 16MHz clock and prescaler of 64, and OCR1A = 49999:
+// 16000000/64/50000 = 20ms period
+#define T1B_PRESCALE_VALUE					64
+void timer_1B_init() {
+	TCCR1A = 0;											// 16.11.1 : Normal operation, OC1A/OC1B disconnected
+	TCCR1B = CTC_TOP_OCR1A_IN_TCCR1B;					// 16.11.2 : CTC mode top OCR1A
+	TCCR1B |= T1_PRESCALE_SET(T1B_PRESCALE_VALUE);		// 16.11.2 : prescaler
+
+	OCR1A = TIME_MS(20, T1B_PRESCALE_VALUE);			// 16.11.5 : Compare match value for register A
+	// OCR1B = ;										// 16.11.6 : Compare match value for register B, since not defined, should default to 0
+
+	TIMSK1 = (1 << OCIE1B);								// 16.11.8 : Enable Timer1 Compare B Match Interrupt
+
+	// ADCSRA |= (1 << ADSC);							// 24.9.2 : start first conversion
+}
+
+ISR(TIMER1_COMPB_vect) {
+    // Empty ISR to ensure proper flag clearing or something like that (p145 : "OCF1B is automatically cleared when the Output Compare Match B Interrupt Vector is executed")
+}

module06/ex00/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
+// }