I'm working for freescale s08 microcontroller and i want help for SPI initialization code in Cplzz help me with the initialization code.

 

I'm not familiar with that model number from the Freescale line. Can you provide a link to a data sheet.

Some questions to think about:

• Do you want code for an SPI master or an SPI peripheral?
• What datarate did you have in mind?
• Which of the four clock and data formats will you be using?

Once you know the answers to those questions the code is two or maybe three assignments statements.

 

the microcontroller is MC9S08DZ60
datasheet link is
http://shops.eccn.com/Freescale/PDFDoc/MC9S08DZ60ACLF.pdf

I want the code for SPI master and clock : active high

 

What is the speed of your bus clock, and what is the speed of the SPI?

 

Bus clock is 20MHz and SPI runs at a baud rate up to the bus clock divided by two in master mode.

 

OK -- that's fine but in order to write the initialization code you have to pick one of the possible baudrates. You can change your mind later if you want, but for the time being you need to pick one.

 

SPI baud rate will be 10MHz

 

Here are the bit definitions and the initialization code you requested.

 

thnks how do i make chip select active low during data transmission?

 

There are at least two ways. If your C-compiler supports bit operations you might write something like:

    PORTA.3 = 0 ; // Take Chip Select Low
    spi_Write(spiData[0]) ;  // Write two bytes of SPI data
    spi_Write(spiData[1]) ;
    PORTA.3 = 1 ; // Take chip select inactive

If your C-compiler does not support operations on individual bits with a READ-MODIFY-WRITE operation then you can synthesize such an operation with the following:

#define SPI_CS  (1<<3)  // Define SPI Chip Select as bit 3 of PORTA
...
    PORTA &= ~SPI_CS ;  // The 1's complement of (1<<3) == 0x10 is 0xF7
    spi_Write(spiData[0]) ;
    spi_Write(spiData[1]) ;
    PORTA |= SPI_CS ;  // Take SPI Chip Select Inactive

Is that as clear as mud or what....?

 

Sorry for the late reply..thanks a lot