CCS C Software and Maintenance Offers
FAQFAQ   FAQForum Help   FAQOfficial CCS Support   SearchSearch  RegisterRegister 

ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

CCS does not monitor this forum on a regular basis.

Please do not post bug reports on this forum. Send them to CCS Technical Support
SPI to 25L640 woes :-(

 
Post new topic   Reply to topic    CCS Forum Index -> General CCS C Discussion
View previous topic :: View next topic  
Author Message
epideath



Joined: 07 Jun 2006
Posts: 47

View user's profile Send private message

SPI to 25L640 woes :-(
PostPosted: Fri Jun 09, 2006 10:29 pm     Reply with quote
(using a 18F4520)

OK having a really tough time trying to communicate to a 25L640 EEPROM. My board electronics all work because I can reload the MCC18 code that I have and it reads and writes to the EEPROM with no problems.

I can't seem to get the PIC to even read one address (zero) from the EEPROM. Crying or Very sad I alos have a write function. but it doesn't seem to work either. I have written a known value to adress zero it is a 1. but after a read it alwyas comes back with zero. Also tried writing a value then read it with my MCC18 program and I can see that it hasn't changed the value. It is the same as that orignally written by the MCC18 program.

I have tried the 25640.c code in the device folder. That doesn't seem to work either. and that doesn't even use the SPI but just drives the I/O directly.

I'm sure that it is something setting wise that i'm over looking. As I'm new to CCS PICC.


Here is the code that I have in CCS PIC-C. Ported from MCC18 that code is below this current code.

I have tried not playing with the SKE and SSPEN. just using the setup_spi. but that doesn't seem to matter one way or the other.

Oh and EditStep.StepType is defined as int8

Hope this makes some sense.

Any pointers or thoughts would be great.
Smile

Thanks

Code:

   SET_TRIS_C(0x10);      //00010000 All output except C4


Code:

      setup_spi(SPI_MASTER|SPI_H_TO_L|SPI_CLK_DIV_4);
   SSPEN = 0;
   SMP = 1;
   CKE = 1;
   SSPEN = 1;




Code:

void Poll_EE(void)
{
   int8 st;
   do
   {
      output_low(PIN_C2);
      spi_write(RDSR);
      st = spi_read();
      output_high(PIN_C2);
   }while(st & 0x01);
}

void LoadStepFromEE(int8 program, int8 step)
{
   int16 address;
   int8 lsb, msb;

   char str[4];

   output_high(PIN_C2);
   address = (int16) program * MAX_STEPS * STEP_SIZE;
   address += (int16)(step-1) * STEP_SIZE;
   lsb = address & 0xFF;
   msb = address >> 8;

   Poll_EE();
   output_low(PIN_C2);
   spi_write(READ_SPI);
   spi_write(0);
   spi_write(0);
   EditStep.StepType = spi_read();
   output_high(PIN_C2);
}




[Here is the MCC18 code that I'm trying to port from.

Code:

void busy_polling (void)
{
   char var;
   do
   {
      PORTCbits.RC2 = 0; //assert chip select
      var = putcSPI(SPI_RDSR); //send read status command
      var = getcSPI(); //read data byte
      PORTCbits.RC2 = 1; //negate chip select
   } while (var & 0x01); //stay in loop until !busy
}

void LoadStepFromEE(char program, char step)
{
   unsigned int address;
   unsigned char address_low, address_high;

   PORTCbits.RC2 = 1;
   //Calculate address high and address low of program/step
   address = (int)(program) * MAX_STEPS * STEP_SIZE;
   address = address + (int)(step-1) * STEP_SIZE;
   address_low = (unsigned char) address & 0xFF;
   address_high = (unsigned char) (address >> 8) & 0xFF;

   OpenSPI(SPI_FOSC_4, MODE_00, SMPEND);
   busy_polling();

   PORTCbits.RC2 = 0;
   putcSPI(SPI_READ);
   putcSPI(address_high);   //Address High
   putcSPI(address_low); //Address Low

   //Read Step Data
   Step.StepType = getcSPI();
   CloseSPI();
   PORTCbits.RC2 = 1;

}
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

View user's profile Send private message

PostPosted: Fri Jun 09, 2006 11:24 pm     Reply with quote
See the following thread, which shows how to use the CCS 25640.C
driver. It's possible that you couldn't make it work because you were
using the wrong pins. The example shows how to use different pins
than the ones defined in the CCS driver file.
http://www.ccsinfo.com/forum/viewtopic.php?t=26212


Also, you should be aware that the following line doesn't generate
an SPI clock:
Code:
st = spi_read();


To generate a clock (from master PIC to slave eeprom), then do this:
Code:
st = spi_read(0);

Note the zero parameter. This is in the manual.
Display posts from previous:   
Post new topic   Reply to topic    CCS Forum Index -> General CCS C Discussion All times are GMT - 6 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group