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116 lines
2.5 KiB
C
116 lines
2.5 KiB
C
/**
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* @file flash.c
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* Provides functionality for using an external SPI flash
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*
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* Copyright (C) 2018 Clyne Sullivan
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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 <https://www.gnu.org/licenses/>.
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*/
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#include <stm32l476xx.h>
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#include <gpio.h>
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#include <clock.h>
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#define READ 0x03
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#define WRITE 0x02
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#define WREN 0x06
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#define WRDS 0x04
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#define NSS GPIO_PORT(B, 12)
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#define SCK GPIO_PORT(B, 13)
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#define MISO GPIO_PORT(B, 14)
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#define MOSI GPIO_PORT(B, 15)
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void flash_xchg(char *byte, int count);
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void flash_init(void)
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{
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gpio_mode(NSS, ALTERNATE);
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gpio_mode(SCK, ALTERNATE);
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gpio_mode(MISO, ALTERNATE);
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gpio_mode(MOSI, ALTERNATE);
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GPIOB->AFR[1] |= 0x55550000; // alt mode SPI2
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// clock enable
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RCC->APB1ENR1 |= RCC_APB1ENR1_SPI2EN;
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SPI2->CR1 &= ~(SPI_CR1_BR_Msk);
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SPI2->CR1 |= (3 << SPI_CR1_BR_Pos);
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SPI2->CR1 |= SPI_CR1_SSM | SPI_CR1_SSI;
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SPI2->CR1 |= SPI_CR1_MSTR;
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SPI2->CR2 &= ~(SPI_CR2_DS_Msk);
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SPI2->CR2 |= (7 << SPI_CR2_DS_Pos);
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SPI2->CR2 |= SPI_CR2_SSOE;
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SPI2->CR2 |= SPI_CR2_FRXTH;
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SPI2->CR1 |= SPI_CR1_SPE;
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char buf[4];
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buf[0] = READ;
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buf[1] = 0;
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buf[2] = 0;
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buf[3] = 0;
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flash_xchg(buf, 4);
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}
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void flash_xchg(char *byte, int count)
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{
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uint32_t status = 0, dummy;
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SPI2->CR1 &= ~(SPI_CR1_SSI);
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while (SPI2->SR & SPI_SR_BSY);
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for (int i = 0; i < count; i++) {
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SPI2->DR = byte[i];
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do status = SPI2->SR;
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while (status & SPI_SR_BSY);
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// discard rx
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while (status & SPI_SR_RXNE) {
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dummy = SPI2->DR;
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status = SPI2->SR;
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}
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}
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do status = SPI2->SR;
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while (status & SPI_SR_BSY);
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while (1) {
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SPI2->DR = 0;
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do status = SPI2->SR;
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while (status & SPI_SR_BSY);
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// discard rx
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while (status & SPI_SR_RXNE) {
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dummy = SPI2->DR;
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status = SPI2->SR;
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}
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}
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SPI2->CR1 |= SPI_CR1_SSI;
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(void)dummy;
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}
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void flash_read(char *buf, uint32_t addr, unsigned int count)
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{
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(void)buf;
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(void)addr;
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(void)count;
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if (buf == 0)
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return;
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}
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void flash_write(const char *buf, uint32_t addr, unsigned int count)
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{
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(void)buf;
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(void)addr;
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(void)count;
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if (buf == 0)
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return;
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}
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