diff --git a/digital_read/Makefile b/digital_read/Makefile index 596fc23..02e1a76 100644 --- a/digital_read/Makefile +++ b/digital_read/Makefile @@ -50,8 +50,8 @@ FORMAT = ihex # Target file name (without extension). TARGET = main -# List C source files here. (C dependencies are automatically generated.) -SRC = $(TARGET).c +# List C source files here. (C dependencies are automatically generated.) +SRC = $(TARGET).c uart_async.c # List Assembler source files here. # Make them always end in a capital .S. Files ending in a lowercase .s diff --git a/digital_read/main.c b/digital_read/main.c index 2f43ddc..a72cbd1 100644 --- a/digital_read/main.c +++ b/digital_read/main.c @@ -14,6 +14,11 @@ * */ + +#ifndef F_CPU +#define F_CPU 16000000UL +#endif + #include #include #include @@ -22,80 +27,88 @@ #include #include "main.h" - -#ifndef F_CPU -#define F_CPU 16000000UL -#endif - -#define BAUD 9600 -#include - -volatile uint8_t interrupts; -char buffer[1]; - -static void uart_init(void) { - UBRR0H = UBRRH_VALUE; - UBRR0L = UBRRL_VALUE; - - UCSR0C = _BV(UCSZ01) | _BV(UCSZ00); - UCSR0B = _BV(RXEN0) | _BV(TXEN0); -} - -static int uart_putchar(char c, FILE *stream) { - loop_until_bit_is_set(UCSR0A, UDRE0); - UDR0 = c; - return 0; -} - -static int uart_getchar(FILE *stream) { - loop_until_bit_is_set(UCSR0A, RXC0); - return UDR0; -} - -static int digital_read(sfr, bit) { - return bit_is_set(sft, bit) && 1; -} +#include "uart.h" void init(void) { - /* Make PORTD3..7 PORTD0..1 (Arduino digital 3..9) input by clearing bits in DDR */ + /* Make PORTD2..7 PORTD0..1 (Arduino digital 3..11) input by clearing bits in DDR */ DDRD &= ~(_BV(PORTD2) | _BV(PORTD3) | _BV(PORTD4) | _BV(PORTD5) | _BV(PORTD6) | _BV(PORTD7)); DDRB &= ~(_BV(PORTB0) | _BV(PORTB1)); - /* Disable pullups by clearing bits in PORT. Default state is now low. */ - /* - PORTD &= ~(_BV(PORTD3) | _BV(PORTD4) | _BV(PORTD5) | _BV(PORTD6) | _BV(PORTD7)); - PORTB &= ~(_BV(PORTB0) | _BV(PORTB1)); - */ - + /* In input mode, when pull-up is enabled, default state of pin becomes ’1′. So even if */ + /* you don’t connect anything to pin and if you try to read it, it will read as 1. Now, */ + /* when you externally drive that pin to zero(i.e. connect to ground / or pull-down), */ + /* only then it will be read as 0. */ + /* Enable pullups by setting bits in PORT. Default state is now high. */ PORTD |= (_BV(PORTD2) | _BV(PORTD3) | _BV(PORTD4) | _BV(PORTD5) | _BV(PORTD6) | _BV(PORTD7)); - PORTB |= (_BV(PORTB0) | _BV(PORTB1)); + PORTB |= (_BV(PORTB0) | _BV(PORTB1)); + + /* Disable pullups by clearing bits in PORT. Default state is now low. */ + /* + PORTD &= ~(_BV(PORTD2) | _BV(PORTD3) | _BV(PORTD4) | _BV(PORTD5) | _BV(PORTD6) | _BV(PORTD7)); + PORTB &= ~(_BV(PORTB0) | _BV(PORTB1)); + */ /* Make PORTB5 (Arduino digital 13) an output by setting bit in DDR. */ DDRB |= _BV(PORTB5); } +int digital_read(int input_register, int pin) { + return bit_is_set(input_register, pin) != 0 ? 1 : 0; +} + +/* +void digital_write(int input_register, int pin) { + input_register |= _BV(pin); +} +*/ + int main(void) { init(); uart_init(); - stdout = &output; - stdin = &input; - - uint8_t value; - char buffer[9]; + stdout = &uart_output; + stdin = &uart_input; + + int value; + //char buffer[9]; while (1) { /* Blink led by toggling state of PORTB5 (Arduino digital 13). */ PORTB ^= _BV(PORTB5); - - /* Take 8bit value from PORTD3..7 PORTD0..1 */ - value = (PIND >> 2) + (PINB << 6); + /* + puts("PINB"); + value = PINB; itoa(value, buffer, 2); puts(buffer); + */ + + value = digital_read(PIND, PIND2); + printf("%d", value); + + value = digital_read(PIND, PIND3); + printf("%d", value); + + value = digital_read(PIND, PIND4); + printf("%d", value); + + value = digital_read(PIND, PIND5); + printf("%d", value); + + value = digital_read(PIND, PIND6); + printf("%d", value); + + value = digital_read(PIND, PIND7); + printf("%d", value); + + value = digital_read(PINB, PINB0); + printf("%d", value); + + value = digital_read(PINB, PINB1); + printf("%d\n", value); _delay_ms(500); } diff --git a/digital_read/main.h b/digital_read/main.h index cf05b2b..26d0812 100644 --- a/digital_read/main.h +++ b/digital_read/main.h @@ -1,8 +1,2 @@ -static int uart_putchar(char c, FILE *stream); -static int uart_getchar(FILE *stream); - -static void init_uart(void); +static void uart_init(void); static void init(void); - -static FILE output = FDEV_SETUP_STREAM(uart_putchar, NULL, _FDEV_SETUP_WRITE); -static FILE input = FDEV_SETUP_STREAM(NULL, uart_getchar, _FDEV_SETUP_READ ); \ No newline at end of file diff --git a/digital_read/uart.h b/digital_read/uart.h new file mode 100644 index 0000000..20ed356 --- /dev/null +++ b/digital_read/uart.h @@ -0,0 +1,12 @@ +int uart_putchar(char c, FILE *stream); +int uart_getchar(FILE *stream); + +void uart_init(void); + +struct rx_ring; +struct tx_ring; + +/* http://www.ermicro.com/blog/?p=325 */ + +FILE uart_output = FDEV_SETUP_STREAM(uart_putchar, NULL, _FDEV_SETUP_WRITE); +FILE uart_input = FDEV_SETUP_STREAM(NULL, uart_getchar, _FDEV_SETUP_READ); diff --git a/digital_read/uart_async.c b/digital_read/uart_async.c new file mode 100644 index 0000000..a9af484 --- /dev/null +++ b/digital_read/uart_async.c @@ -0,0 +1,102 @@ +/* Based on Atmel Application Note AVR 306 */ + +#include +#include +#include + +#ifndef BAUD +#define BAUD 9600 +#endif +#include + +#ifndef UART_RX_BUFFER_SIZE +#define UART_RX_BUFFER_SIZE 64 +#endif + +#ifndef UART_TX_BUFFER_SIZE +#define UART_TX_BUFFER_SIZE 64 +#endif + +struct tx_ring { + int buffer[UART_TX_BUFFER_SIZE]; + int start; + int end; +}; + +struct rx_ring { + int buffer[UART_RX_BUFFER_SIZE]; + int start; + int end; +}; + +static struct tx_ring tx_buffer; +static struct rx_ring rx_buffer; + +/* http://www.cs.mun.ca/~rod/Winter2007/4723/notes/serial/serial.html */ + +void uart_init(void) { + + tx_buffer.start = 0; + tx_buffer.end = 0; + + rx_buffer.start = 0; + rx_buffer.end = 0; + + UBRR0H = UBRRH_VALUE; + UBRR0L = UBRRL_VALUE; + + UCSR0C = _BV(UCSZ01) | _BV(UCSZ00); /* 8-bit data */ + UCSR0B = _BV(RXEN0) | _BV(TXEN0); /* Enable RX and TX */ + + sei(); +} + +int uart_putchar(char c, FILE *stream) { + if (c == '\n') { + uart_putchar('\r', stream); + } + + int write_pointer = (tx_buffer.end + 1) % UART_TX_BUFFER_SIZE; + + if (write_pointer != tx_buffer.start){ + tx_buffer.buffer[tx_buffer.end] = c; + tx_buffer.end = write_pointer; + + /* Data available. Enable the transmit interrupt for serial port 0. */ + UCSR0B |= _BV(UDRIE0); + } + + return 0; +} + +int uart_getchar(FILE *stream) { + int read_pointer = (rx_buffer.start + 1) % UART_RX_BUFFER_SIZE; + + rx_buffer.start = read_pointer; + return rx_buffer.buffer[read_pointer]; +} + +ISR(USART_RX_vect) { + int write_pointer = (rx_buffer.end + 1) % UART_RX_BUFFER_SIZE; + + /* Add next byte to ringbuffer if it has space available. */ + if (write_pointer != rx_buffer.start){ + rx_buffer.buffer[rx_buffer.end] = UDR0; + rx_buffer.end = write_pointer; + } +} + +ISR(USART_UDRE_vect){ + int read_pointer = (tx_buffer.start + 1) % UART_TX_BUFFER_SIZE; + + /* Transmit next byte if data available in ringbuffer. */ + if (read_pointer != tx_buffer.end) { + UDR0 = tx_buffer.buffer[read_pointer]; + tx_buffer.start = read_pointer; + } else { + /* Nothing to send. Disable the transmit interrupt for serial port 0. */ + UCSR0B &= ~_BV(UDRIE0); + } +} + +