CVS: libraries/spi makefile,NONE,1.1 shiftregister.c,NONE,1.1 spi_shift.c,NONE,1.1 spi_transfer.c,NONE,1.1

Update of /cvsroot/mspgcc/libraries/spi
In directory sc8-pr-cvs1.sourceforge.net:/tmp/cvs-serv20805/libraries/spi

Added Files:
	makefile shiftregister.c spi_shift.c spi_transfer.c 
Log Message:
initial import of spi library

features a software SPI master, a  function to access a shiftregister, and an io function for SPI transfers

--- NEW FILE: makefile ---
# makfile configuration
LIBRARYNAME     = spi
CSOURCES        = shiftregister.c spi_shift.c spi_transfer.c
#~ ASOURCES        = 
CPU             = msp1

ASFLAGS         = -mmcu=${CPU} -D_GNU_ASSEMBLER_ -I ../include
CFLAGS          = -mmcu=${CPU} -O2 -Wall -std=gnu99 -g -I ../include

#switch the compiler (for the internal make rules)
CC              = msp430-gcc
AS              = msp430-gcc
AR              = msp430-ar

OBJECTS         = ${CSOURCES:.c=.o} ${ASOURCES:.S=.o}

.PHONY: all FORCE clean

#all should be the first target. it's built when make is run without args
all: lib$(LIBRARYNAME).a lib$(LIBRARYNAME).lst dependencies.d

lib$(LIBRARYNAME).a: $(OBJECTS)
	$(AR) rcf $@ $^

lib$(LIBRARYNAME).lst: lib$(LIBRARYNAME).a
	msp430-objdump -dSt $^ >$@
	@echo "----- RAM/Flash Usage -----"
	msp430-size $^

clean:
	rm -f lib$(LIBRARYNAME).a lib$(LIBRARYNAME).lst ${OBJECTS} dependencies.d


#dummy target as dependecy if something has to be build everytime
FORCE:

#project dependencies
dependencies.d:
	$(CC) -MM ${CFLAGS} ${CSOURCES} > dependencies.d
ifdef ASOURCES
	$(CC) -MM ${ASFLAGS} ${ASOURCES} >> dependencies.d
endif

-include dependencies.d
--- NEW FILE: shiftregister.c ---
#include "spi.h"

// simple shift only function
// useful for simple shift registers
void spi_push(unsigned char width, unsigned long data) {
    SPI_CLK_SET();              //ensure propper start
    SPI_CS_CLEAR();             //begin transmit
    while(width--) {
        SPI_CLK_CLEAR();        //begin bit
        if (data & 1) {         //check bit and set data line accordingly
            SPI_DATA_SET();
        } else {
            SPI_DATA_CLEAR();
        }
        SPI_CLK_SET();          //end bit
        data >>= 1;
    }
    SPI_CS_SET();               //end transmit
    SPI_DATA_SET();             //return to idle position
}

--- NEW FILE: spi_shift.c ---
#include "spi.h"

// shift one byte out while reading one
unsigned char spi_shift(unsigned char data) {
    unsigned char result = 0;
    SPI_CLK_SET();              //ensure propper start
    SPI_CS_CLEAR();             //begin transmit
    for (int width=8; width; width--) {
        SPI_CLK_CLEAR();        //begin bit
        if (data & 0x80) {      //check bit and set data line accordingly
            SPI_DATA_SET();
        } else {
            SPI_DATA_CLEAR();
        }
        SPI_CLK_SET();          //end bit
        data <<= 1;
        result <<= 1;
        result |= SPI_DATA_READ() ? 1 : 0;
    }
    SPI_CS_SET();               //end transmit
    SPI_DATA_SET();             //return to idle position
    return result;
}

--- NEW FILE: spi_transfer.c ---
#include "spi.h"

// send and receive an array of bytes
// either one of the buffers may be NULL, in that case it is ignored:
// if output is NULL -> send 0xff
// if input is NULL -> forget received data
// it is valid, tough not very useful to set both pointers to NULL

void spi_transfer(void *output, const void *input, int length) {
    unsigned char in;
    unsigned char out = 0xff;
    
    while (length--) {
        if (output) out = *((unsigned char *)output)++;
        in = spi_shift(out);
        if (input) *((unsigned char *)input)++ = in;
    }
}



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