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Add initial SPI code.

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For now, add the following basic SPI functions:

 - spi_init_master()
 - spi_write()
 - spi_read()

This is incomplete and untested, yet.

Also, add some more SPI bit definition macros and comments.
This commit is contained in:
Uwe Hermann 2009-12-30 23:09:14 +01:00
parent 821873acac
commit a7a3770d51
3 changed files with 111 additions and 25 deletions
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70
include/libopenstm32/spi.h
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@ -93,44 +93,66 @@
/* Note: None of the CR1 bits are used in I2S mode. */
#define SPI_CR1_BIDIMODE (1 << 15)
/* BIDIMODE: Bidirectional data mode enable */
#define SPI_CR1_BIDIMODE_2LINE_UNIDIR (0 << 15)
#define SPI_CR1_BIDIMODE_1LINE_BIDIR (1 << 15)
/* BIDIOE: Output enable in bidirectional mode */
#define SPI_CR1_BIDIOE (1 << 14)
/* CRCEN: Hardware CRC calculation enable */
#define SPI_CR1_CRCEN (1 << 13)
/* CRCNEXT: Transmit CRC next */
#define SPI_CR1_CRCNEXT (1 << 12)
#define SPI_CR1_DFF (1 << 11)
/* DFF: Data frame format */
#define SPI_CR1_DFF_8BIT (0 << 11)
#define SPI_CR1_DFF_16BIT (1 << 11)
/* RXONLY: Receive only */
#define SPI_CR1_RXONLY (1 << 10)
/* SSM: Software slave management */
#define SPI_CR1_SSM (1 << 9)
/* SSI: Internal slave select */
#define SPI_CR1_SSI (1 << 8)
/* LSBFIRST: Frame format */
#define SPI_CR1_MSBFIRST (0 << 7)
#define SPI_CR1_LSBFIRST (1 << 7)
/* SPE: SPI enable */
#define SPI_CR1_SPE (1 << 6)
/* SPI_CR1[5:3]: BR[2:0]: Baud rate control: */
#define SPI_CR1_BR (1 << 3)
/* BR[2:0]: Baud rate control */
#define SPI_CR1_BAUDRATE_FPCLK_DIV_2 (0x00 << 3)
#define SPI_CR1_BAUDRATE_FPCLK_DIV_4 (0x01 << 3)
#define SPI_CR1_BAUDRATE_FPCLK_DIV_8 (0x02 << 3)
#define SPI_CR1_BAUDRATE_FPCLK_DIV_16 (0x03 << 3)
#define SPI_CR1_BAUDRATE_FPCLK_DIV_32 (0x04 << 3)
#define SPI_CR1_BAUDRATE_FPCLK_DIV_64 (0x05 << 3)
#define SPI_CR1_BAUDRATE_FPCLK_DIV_128 (0x06 << 3)
#define SPI_CR1_BAUDRATE_FPCLK_DIV_256 (0x07 << 3)
/* MSTR: Master selection */
#define SPI_CR1_MSTR (1 << 2)
#define SPI_CR1_CPOL (1 << 1)
#define SPI_CR1_CPHA (1 << 0)
/* CR1_BIDIMODE values */
#define SPI_CR1_BIDIMODE_2LINE_UNIDIR 0x00
#define SPI_CR1_BIDIMODE_1LINE_BIDIR 0x01
/* CPOL: Clock polarity */
#define SPI_CR1_CPOL_CLK_TO_0_WHEN_IDLE (0 << 1)
#define SPI_CR1_CPOL_CLK_TO_1_WHEN_IDLE (1 << 1)
/* CR1_DFF (data frame format) values */
#define SPI_CR1_DFF_8BIT 0x00
#define SPI_CR1_DFF_16BIT 0x01
/* CR1_BR[2:0] values */
#define SPI_CR1_BAUDRATE_FPCLK_DIV_2 0x00
#define SPI_CR1_BAUDRATE_FPCLK_DIV_4 0x01
#define SPI_CR1_BAUDRATE_FPCLK_DIV_8 0x02
#define SPI_CR1_BAUDRATE_FPCLK_DIV_16 0x03
#define SPI_CR1_BAUDRATE_FPCLK_DIV_32 0x04
#define SPI_CR1_BAUDRATE_FPCLK_DIV_64 0x05
#define SPI_CR1_BAUDRATE_FPCLK_DIV_128 0x06
#define SPI_CR1_BAUDRATE_FPCLK_DIV_256 0x07
/* TODO: Bit values of other registers. */
/* CPHA: Clock phase */
#define SPI_CR1_CPHA_CLK_TRANSITION_1 (0 << 0)
#define SPI_CR1_CPHA_CLK_TRANSITION_2 (1 << 0)
/* --- Function prototypes ------------------------------------------------- */
int spi_init_master(u32 spi, u32 br, u32 cpol, u32 cpha, u32 dff, u32 lsbfirst);
void spi_write(u32 spi, u16 data);
u16 spi_read(u32 spi);
/* TODO */
#endif

2
lib/Makefile
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@ -27,7 +27,7 @@ CFLAGS = -Os -g -Wall -Wextra -I../include -fno-common \
-mcpu=cortex-m3 -mthumb -Wstrict-prototypes
# ARFLAGS = rcsv
ARFLAGS = rcs
OBJS = rcc.o gpio.o usart.o adc.o
OBJS = rcc.o gpio.o usart.o adc.o spi.o
# Be silent per default, but 'make V=1' will show all compiler calls.
ifneq ($(V),1)

64
lib/spi.c Normal file
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@ -0,0 +1,64 @@
/*
* This file is part of the libopenstm32 project.
*
* Copyright (C) 2009 Uwe Hermann <uwe@hermann-uwe.de>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <libopenstm32.h>
/*
* SPI and I2S code.
*
* Examples:
* spi_init_master(SPI1, 1000000, SPI_CR1_CPOL_CLK_TO_0_WHEN_IDLE,
* SPI_CR1_CPHA_CLK_TRANSITION_1, SPI_CR1_DFF_8BIT,
* SPI_CR1_LSBFIRST);
* spi_write(SPI1, 0x55); // 8-bit write
* spi_write(SPI1, 0xaa88); // 16-bit write
* reg8 = spi_read(SPI1); // 8-bit read
* reg16 = spi_read(SPI1); // 16-bit read
*/
int spi_init_master(u32 spi, u32 br, u32 cpol, u32 cpha, u32 dff, u32 lsbfirst)
{
u32 reg32 = 0;
reg32 |= br; /* Set BAUD rate bits. */
reg32 |= cpol; /* Set CPOL value. */
reg32 |= cpha; /* Set CPHA value. */
reg32 |= dff; /* Set data format (8 or 16 bits). */
reg32 |= lsbfirst; /* Set frame format (LSB-first or MSB-first). */
/* TODO: NSS pin handling. */
/* TODO: Set MSTR and SPE bits. */
SPI_CR1(spi) = reg32;
return 0; /* TODO */
}
void spi_write(u32 spi, u16 data)
{
/* Write data (8 or 16 bits, depending on DFF) into DR. */
SPI_DR(spi) = data;
}
u16 spi_read(u32 spi)
{
/* Read the data (8 or 16 bits, depending on DFF bit) from DR. */
return SPI_DR(spi);
}