diff options
Diffstat (limited to 'tmk_core/common/uart.c')
| -rw-r--r-- | tmk_core/common/uart.c | 132 |
1 files changed, 63 insertions, 69 deletions
diff --git a/tmk_core/common/uart.c b/tmk_core/common/uart.c index c17649b082..f2e4bc4f34 100644 --- a/tmk_core/common/uart.c +++ b/tmk_core/common/uart.c @@ -3,17 +3,17 @@ /* UART Example for Teensy USB Development Board * http://www.pjrc.com/teensy/ * Copyright (c) 2009 PJRC.COM, LLC - * + * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: - * + * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. - * + * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE @@ -26,7 +26,6 @@ // Version 1.0: Initial Release // Version 1.1: Add support for Teensy 2.0, minor optimizations - #include <avr/io.h> #include <avr/interrupt.h> @@ -44,86 +43,81 @@ static volatile uint8_t rx_buffer_head; static volatile uint8_t rx_buffer_tail; // Initialize the UART -void uart_init(uint32_t baud) -{ - cli(); - UBRR0 = (F_CPU / 4 / baud - 1) / 2; - UCSR0A = (1<<U2X0); - UCSR0B = (1<<RXEN0) | (1<<TXEN0) | (1<<RXCIE0); - UCSR0C = (1<<UCSZ01) | (1<<UCSZ00); - tx_buffer_head = tx_buffer_tail = 0; - rx_buffer_head = rx_buffer_tail = 0; - sei(); +void uart_init(uint32_t baud) { + cli(); + UBRR0 = (F_CPU / 4 / baud - 1) / 2; + UCSR0A = (1 << U2X0); + UCSR0B = (1 << RXEN0) | (1 << TXEN0) | (1 << RXCIE0); + UCSR0C = (1 << UCSZ01) | (1 << UCSZ00); + tx_buffer_head = tx_buffer_tail = 0; + rx_buffer_head = rx_buffer_tail = 0; + sei(); } // Transmit a byte -void uart_putchar(uint8_t c) -{ - uint8_t i; - - i = tx_buffer_head + 1; - if (i >= TX_BUFFER_SIZE) i = 0; - while (tx_buffer_tail == i) ; // wait until space in buffer - //cli(); - tx_buffer[i] = c; - tx_buffer_head = i; - UCSR0B = (1<<RXEN0) | (1<<TXEN0) | (1<<RXCIE0) | (1<<UDRIE0); - //sei(); +void uart_putchar(uint8_t c) { + uint8_t i; + + i = tx_buffer_head + 1; + if (i >= TX_BUFFER_SIZE) i = 0; + while (tx_buffer_tail == i) + ; // wait until space in buffer + // cli(); + tx_buffer[i] = c; + tx_buffer_head = i; + UCSR0B = (1 << RXEN0) | (1 << TXEN0) | (1 << RXCIE0) | (1 << UDRIE0); + // sei(); } // Receive a byte -uint8_t uart_getchar(void) -{ - uint8_t c, i; - - while (rx_buffer_head == rx_buffer_tail) ; // wait for character - i = rx_buffer_tail + 1; - if (i >= RX_BUFFER_SIZE) i = 0; - c = rx_buffer[i]; - rx_buffer_tail = i; - return c; +uint8_t uart_getchar(void) { + uint8_t c, i; + + while (rx_buffer_head == rx_buffer_tail) + ; // wait for character + i = rx_buffer_tail + 1; + if (i >= RX_BUFFER_SIZE) i = 0; + c = rx_buffer[i]; + rx_buffer_tail = i; + return c; } // Return the number of bytes waiting in the receive buffer. // Call this before uart_getchar() to check if it will need // to wait for a byte to arrive. -uint8_t uart_available(void) -{ - uint8_t head, tail; - - head = rx_buffer_head; - tail = rx_buffer_tail; - if (head >= tail) return head - tail; - return RX_BUFFER_SIZE + head - tail; +uint8_t uart_available(void) { + uint8_t head, tail; + + head = rx_buffer_head; + tail = rx_buffer_tail; + if (head >= tail) return head - tail; + return RX_BUFFER_SIZE + head - tail; } // Transmit Interrupt -ISR(USART_UDRE_vect) -{ - uint8_t i; - - if (tx_buffer_head == tx_buffer_tail) { - // buffer is empty, disable transmit interrupt - UCSR0B = (1<<RXEN0) | (1<<TXEN0) | (1<<RXCIE0); - } else { - i = tx_buffer_tail + 1; - if (i >= TX_BUFFER_SIZE) i = 0; - UDR0 = tx_buffer[i]; - tx_buffer_tail = i; - } +ISR(USART_UDRE_vect) { + uint8_t i; + + if (tx_buffer_head == tx_buffer_tail) { + // buffer is empty, disable transmit interrupt + UCSR0B = (1 << RXEN0) | (1 << TXEN0) | (1 << RXCIE0); + } else { + i = tx_buffer_tail + 1; + if (i >= TX_BUFFER_SIZE) i = 0; + UDR0 = tx_buffer[i]; + tx_buffer_tail = i; + } } // Receive Interrupt -ISR(USART_RX_vect) -{ - uint8_t c, i; - - c = UDR0; - i = rx_buffer_head + 1; - if (i >= RX_BUFFER_SIZE) i = 0; - if (i != rx_buffer_tail) { - rx_buffer[i] = c; - rx_buffer_head = i; - } +ISR(USART_RX_vect) { + uint8_t c, i; + + c = UDR0; + i = rx_buffer_head + 1; + if (i >= RX_BUFFER_SIZE) i = 0; + if (i != rx_buffer_tail) { + rx_buffer[i] = c; + rx_buffer_head = i; + } } - |