80 lines
2.1 KiB
C
80 lines
2.1 KiB
C
/* Copyright © 2020 tyrolyean
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU 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
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "avr.h"
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#include "16550.h"
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#include "structures.h"
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#include <stdio.h>
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static FILE stdout_16550 = FDEV_SETUP_STREAM(putchar_16550, NULL,
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_FDEV_SETUP_WRITE);
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void write_to_uart(uint8_t addr, uint8_t data){
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set_addr(addr);
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DATA_DDR_REG = 0xFF;
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DATA_REG = data;
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CTRL_REG &= ~(1<<WR_SHIFT) & ~(1<<CS_UART_SHIFT);
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_delay_us(BUS_HOLD_US); /*Wait for the data and signal lanes to become stable*/
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CTRL_REG |= 1<<CS_UART_SHIFT | 1<<WR_SHIFT;
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return;
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}
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uint8_t read_from_uart(uint8_t addr){
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uint8_t data = 0x00;
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set_addr(addr);
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DATA_DDR_REG = 0x00;
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/* Sometimes the avr "forgets" to alter the port register for one cycle
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* which usually isn't a problem but has lead to instability. Worthy
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* one clock cycle */
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DATA_REG = 0x00;
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CTRL_REG &= ~(1<<RD_SHIFT) & ~(1<<CS_UART_SHIFT);
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_delay_us(BUS_HOLD_US); /* Wait for the data and signal lanes to become
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* stable*/
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data = PINF;
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CTRL_REG |= 1<<CS_UART_SHIFT | 1<<RD_SHIFT;
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return data;
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}
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void init_uart(){
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write_to_uart(UART_REG_LCR,0x83);
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write_to_uart(UART_REG_DLLS,0x03);
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write_to_uart(UART_REG_DLMS,0x00);
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write_to_uart(UART_REG_LCR,0x03);
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stdout = &stdout_16550;
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printf("INIT\r\n");
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return;
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}
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int putchar_16550(char var, FILE *stream __attribute__((unused))){
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for(uint32_t i = 0; i < 1000000; i++ ){
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uint8_t received = read_from_uart(UART_REG_LSR);
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if((received & (1<<5))){
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break;
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}
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}
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write_to_uart(UART_REG_TXRX,var);
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return 0;
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}
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