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kideltn
Joined: 08 Jun 2010
Posts: 13
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| Problem with function interface spi in CCS |
 Posted: Tue Jul 06, 2010 10:38 am |
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I'm debugging sdcard interface is to problem with spi function in CCS.
My schematic:(18f4550+sdcard)
I used spi solfware:
| Code: | #define CS PIN_D3
#define SCK PIN_D6
#define SDO PIN_D5
#define SDI PIN_D4
#use spi( DI=SDI, DO=SDO, CLK=SCK, BITS=8, stream=sspi) |
And the error occurs as above(at the connection between RD5 and D0 has the error:the logic contention)
I thought the pins PORTD was multiplexed so i added
| Code: | | TRISD =0b00100010;//D0 and TXD is input |
but still not successful.
Please help me ...!
Thanks a lot ! |
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kideltn
Joined: 08 Jun 2010
Posts: 13
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| Posted: Tue Jul 06, 2010 11:03 am |
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My code: | Code: |
#include "basicsd.h"
#define CS PIN_D3
#define SCK PIN_D6
#define SDO PIN_D5
#define SDI PIN_D4
#use spi( DI=SDI, DO=SDO, CLK=SCK, BITS=8, stream=sspi)
#define _DEBUG
#ifdef _DEBUG
#define dbg(str) printf(str)
#endif
// Prototypes
void command(int8, int16, int16, int8);
int mmc_init();
// Implementations
// Send 6-byte Command to MMC
void command(int8 cmd, int16 adh, int16 adl, int8 crc)
{
spi_xfer(sspi,cmd);
spi_xfer(sspi,make8(adh,1));
spi_xfer(sspi,make8(adh,0));
spi_xfer(sspi,make8(adl,1));
spi_xfer(sspi,make8(adh,0));
spi_xfer(sspi,crc);
}
// Initialize the Card
int mmc_init()
{
int16 i;
// Unselect Card and Send some Dummy Clocks
output_high(CS);
for(i= 0; i< 10; i++)
{
spi_xfer(sspi,0xEF);
}
// Select Card
output_low(CS);
// Send Command 0x40: Wake Up the Card
command(0x40, 0, 0, 0x95);
for(i= 0; i< 100; i++)
{
if(spi_xfer()== 0x01)
{
break;
}
}
if(i>= 100) // Check for Time-out Error
{
return(1);
}
dbg("CMD40 OK (R1= 0x01)\n\r");
// Send Command 0x41: Start Initialize
command(0x41, 0, 0, 0xFF);
for(i= 0; i< 1000; i++)
{
if(spi_xfer()== 0x00)
{
break;
}
}
if(i>= 1000) // Check for Time-out Error
{
return(1);
}
dbg("CMD41 OK (R1= 0x00)\n\r");
// Return OK
return 0;
}
void main()
{
printf("> MMC Test by DEBUGGER...\n\r");
printf("> Start MMC Init...\n\r");
if(mmc_init()== 0)
{
printf("> MMC Init Ok...\r\n");
}
else
{
printf("> failure.continue debug!\r\n");
}
while(1);
} |
My above code tested success with pic 16f877a (with the same pins) |
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FvM
Joined: 27 Aug 2008
Posts: 2337
Location: Germany
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| Posted: Tue Jul 06, 2010 11:46 am |
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| SPI DO is an output at the processor. |
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ckielstra
Joined: 18 Mar 2004
Posts: 3680
Location: The Netherlands
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| Posted: Tue Jul 06, 2010 12:27 pm |
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And the other common issues:
- The no pull-up resistors on the DO and DO lines are missing.
- You have not specified the SPI mode in the setup of '#use SPI'. MMC and SD cards can be used in either SPI-mode 0 or 3.
- Your PIC should be running at 3.3V, not 5V (you might be lucky if it works in Proteus, but it will kill real hardware).
- Post your compiler version (the SPI_xfer routines are known to be broken in older v4 compiler versions). |
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kideltn
Joined: 08 Jun 2010
Posts: 13
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| Posted: Wed Jul 07, 2010 5:34 am |
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Thanks every one very much !
I have solved it! (error is confused DO and DI). |
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