104 lines
3.5 KiB
C
104 lines
3.5 KiB
C
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/*
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* Copyright (C) 2018 bzt (bztsrc@github)
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*
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* Permission is hereby granted, free of charge, to any person
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* obtaining a copy of this software and associated documentation
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* files (the "Software"), to deal in the Software without
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* restriction, including without limitation the rights to use, copy,
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* modify, merge, publish, distribute, sublicense, and/or sell copies
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* of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
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* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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* DEALINGS IN THE SOFTWARE.
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*
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*/
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#include "gpio.h"
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/* Auxilary mini UART registers */
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#define AUX_ENABLE ((volatile unsigned int*)(MMIO_BASE+0x00215004))
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#define AUX_MU_IO ((volatile unsigned int*)(MMIO_BASE+0x00215040))
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#define AUX_MU_IER ((volatile unsigned int*)(MMIO_BASE+0x00215044))
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#define AUX_MU_IIR ((volatile unsigned int*)(MMIO_BASE+0x00215048))
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#define AUX_MU_LCR ((volatile unsigned int*)(MMIO_BASE+0x0021504C))
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#define AUX_MU_MCR ((volatile unsigned int*)(MMIO_BASE+0x00215050))
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#define AUX_MU_LSR ((volatile unsigned int*)(MMIO_BASE+0x00215054))
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#define AUX_MU_MSR ((volatile unsigned int*)(MMIO_BASE+0x00215058))
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#define AUX_MU_SCRATCH ((volatile unsigned int*)(MMIO_BASE+0x0021505C))
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#define AUX_MU_CNTL ((volatile unsigned int*)(MMIO_BASE+0x00215060))
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#define AUX_MU_STAT ((volatile unsigned int*)(MMIO_BASE+0x00215064))
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#define AUX_MU_BAUD ((volatile unsigned int*)(MMIO_BASE+0x00215068))
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/**
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* Set baud rate and characteristics (115200 8N1) and map to GPIO
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*/
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void uart_init()
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{
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register unsigned int r;
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/* initialize UART */
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*AUX_ENABLE |=1; // enable UART1, AUX mini uart
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*AUX_MU_CNTL = 0;
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*AUX_MU_LCR = 3; // 8 bits
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*AUX_MU_MCR = 0;
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*AUX_MU_IER = 0;
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*AUX_MU_IIR = 0xc6; // disable interrupts
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*AUX_MU_BAUD = 270; // 115200 baud
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/* map UART1 to GPIO pins */
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r=*GPFSEL1;
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r&=~((7<<12)|(7<<15)); // gpio14, gpio15
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r|=(2<<12)|(2<<15); // alt5
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*GPFSEL1 = r;
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*GPPUD = 0; // enable pins 14 and 15
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r=150; while(r--) { asm volatile("nop"); }
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*GPPUDCLK0 = (1<<14)|(1<<15);
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r=150; while(r--) { asm volatile("nop"); }
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*GPPUDCLK0 = 0; // flush GPIO setup
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*AUX_MU_CNTL = 3; // enable Tx, Rx
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}
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/**
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* Send a character
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*/
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void uart_send(unsigned int c) {
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/* wait until we can send */
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do{asm volatile("nop");}while(!(*AUX_MU_LSR&0x20));
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/* write the character to the buffer */
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*AUX_MU_IO=c;
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}
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/**
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* Receive a character
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*/
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char uart_getc() {
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char r;
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/* wait until something is in the buffer */
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do{asm volatile("nop");}while(!(*AUX_MU_LSR&0x01));
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/* read it and return */
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r=(char)(*AUX_MU_IO);
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/* convert carrige return to newline */
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return r=='\r'?'\n':r;
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}
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/**
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* Display a string
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*/
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void uart_puts(char *s) {
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while(*s) {
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/* convert newline to carrige return + newline */
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if(*s=='\n')
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uart_send('\r');
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uart_send(*s++);
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}
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}
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