mirror of
https://github.com/sjlongland/cluster-powerctl.git
synced 2025-09-14 04:23:15 +10:00
117 lines
2.4 KiB
C
117 lines
2.4 KiB
C
/*!
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* Very simple software UART for AVR microcontrollers
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* (C) 2016 Stuart Longland
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include "uart.h"
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#include "uartcfg.h"
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#include <avr/io.h>
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#include <util/delay.h>
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#include <stdint.h>
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#include <avr/pgmspace.h>
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#define TX_BIT (1 << UART_TX_BIT)
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#define BIT_US (1000000/UART_BAUD) /*!< Bit period in microseconds */
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static volatile uint8_t uart_ticks = 0;
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/*!
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* Configure the UART pins.
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*/
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void uart_init() {
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UART_TX_DDR |= TX_BIT;
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UART_TX_PORT |= TX_BIT;
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}
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static void uart_wait(uint8_t ticks) {
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uart_ticks = ticks;
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while(uart_ticks);
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}
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void uart_tick() {
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if (uart_ticks)
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uart_ticks--;
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}
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/*!
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* Send a raw byte to the UART.
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*/
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void uart_tx(uint8_t byte) {
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uint8_t mask = 1;
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/* Start bit */
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UART_TX_PORT &= ~TX_BIT; uart_wait(1);
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while(mask) {
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if (mask & byte)
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UART_TX_PORT |= TX_BIT;
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else
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UART_TX_PORT &= ~TX_BIT;
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uart_wait(1);
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mask <<= 1;
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}
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/* Stop bit */
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UART_TX_PORT |= TX_BIT; uart_wait(1);
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}
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/*!
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* Send a text string (in pgmspace) to the UART.
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* String shall be null-terminated!
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*/
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void uart_tx_str(const char* str) {
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char c = pgm_read_byte(str);
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while (c) {
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str++;
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uart_tx(c);
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c = pgm_read_byte(str);
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}
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}
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/*!
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* Send a 4-bit nybble to the UART.
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*/
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void uart_tx_hex(uint8_t nybble) {
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if (nybble >= 10)
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uart_tx(nybble - 10 + 'a');
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else
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uart_tx(nybble + '0');
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}
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/*!
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* Send a 8-bit byte to the UART.
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*/
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void uart_tx_hex_byte(uint8_t byte) {
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uart_tx_hex(byte >> 4);
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uart_tx_hex(byte & 0x0f);
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}
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/*!
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* Send a 16-bit word to the UART.
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*/
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void uart_tx_hex_word(uint16_t word) {
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uart_tx_hex_byte(word >> 8);
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uart_tx_hex_byte(word & 0xff);
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}
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/*!
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* Send a 32-bit long word to the UART.
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*/
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void uart_tx_hex_lword(uint32_t lword) {
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uart_tx_hex_word(lword >> 16);
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uart_tx_hex_word(lword & 0xffff);
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}
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