mirror of
https://github.com/eddyem/STM8_samples.git
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108 lines
2.7 KiB
C
108 lines
2.7 KiB
C
/*
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* spi.c
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*
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* Copyright 2016 Edward V. Emelianov <eddy@sao.ru, edward.emelianoff@gmail.com>
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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 2 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, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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* MA 02110-1301, USA.
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*/
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#include "ports_definition.h"
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#include "spi.h"
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// global variables for sending big buffer
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static U16 sendbuflen = 0;
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static U8 *sendbuf = NULL, *inbuff = NULL;
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/*
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* SPI registers
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* SPI_CR1 (page 271): | LSBFIRST | SPE | BR[2:0] | MSTR | CPOL | CPHA |
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* BR: xxx - f/2^{xxx+1}
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* 01111100
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* SPI_CR2 (page 272): | BDM | BDOE | CRCEN | CRCNEXT | - | RXONLY | SSM | SSI |
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* 00000000
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* SPI_ICR (page 273): | TXIE | RXIE | ERRIE | WKIE | - | - | - | - |
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* SPI_SR (page 274): | BSY | OVR | MODF | CRCERR | WKUP | - | TXE | RXNE |
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* set it to zero before send new byte
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*/
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void spi_init(){
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// pins config: MISO is pullup in, MOSI & SCK are pp out
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PORT(SPI_PORT, DDR) |= SPI_MOSI_PIN | SPI_SCK_PIN;
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PORT(SPI_PORT, CR1) |= SPI_MOSI_PIN | SPI_SCK_PIN | SPI_MISO_PIN;
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// setup line: f/256, enable, master
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SPI_CR1 = SPI_CR1_SPE | SPI_CR1_BRMASK | SPI_CR1_MSTR;
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SPI_CR2 = 0;
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}
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/**
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* static routine waiting SPI free
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*/
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static void spi_wait(){
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while(!(SPI_SR & SPI_SR_TXE))
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while(SPI_SR & SPI_SR_BSY);
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}
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/**
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* send given data buffer
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* WARNING! Buffer should have livetime at least while !spi_buf_sent()
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* set _get == 1 to put received data into the same buffer
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*/
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void spi_send_buffer(U8 *buff, U16 len, U8 *inb){
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inbuff = inb;
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sendbuflen = len;
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sendbuf = buff;
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spi_wait();
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SPI_DR = *sendbuf;
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// interrupts: RXNE
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SPI_ICR = SPI_ICR_RXIE;
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}
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/**
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* send next byte from sendbuf (called by interrupt routine)
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*/
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void spi_send_next(){
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if(!sendbuf) return;
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if(inbuff){
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//while(!(SPI_SR & SPI_SR_RXNE));
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*inbuff++ = SPI_DR;
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}
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if(--sendbuflen == 0){
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sendbuf = NULL;
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SPI_ICR = 0;
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return;
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}
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SPI_DR = *(++sendbuf);
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}
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/**
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* blocking send 1 byte & return ansver
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*/
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U8 spi_send_byte(U8 data){
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spi_wait();
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SPI_ICR = 0;
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SPI_DR = data;
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while(!(SPI_SR & SPI_SR_RXNE));
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return SPI_DR;
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}
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/**
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* return 1 if there's no data in queue to send
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*/
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U8 spi_buf_sent(){
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if(!sendbuf) return 1;
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else return 0;
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}
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