I want to communicate with a SPI serial flash.
I've seen enough code to initialize the SPI port.
However, I can't find any sample code that will
show me how to tx and rx bytes in page mode.
In the AT91_CDROM, I see a file called :
AT91M55800A-BasicSPI-GHS3_6-2_0.zip
Can I re-use some of the code for the SAM7S64?
Are the SPI registers the same?
Thanks
SPI help
Started by ●May 4, 2005
Reply by ●May 4, 20052005-05-04
I normally take the weasle approach with SPI and bit-bang it using GPIO
routines.
If you're just doing relatively infrequent communications to SEEPROMS
etc then this approach is fine. By bypassing all the SPI stuff you can
make things a lot simpler.
Of course there are times when you really need the throughput of using
the SPI peripheral and then it is worth doing the hard yards.
The other point is that the various seeprom and flash devices have
different command interfaces. You typically need to opull the datasheet
for the device you're using and go with that.
> -----Original Message-----
> From: AT91SAM7@AT91...
> [mailto:AT91SAM7@AT91...] On Behalf Of at91sam7s
> Sent: Thursday, 5 May 2005 11:47 a.m.
> To: AT91SAM7@AT91...
> Subject: [AT91SAM7] SPI help > I want to communicate with a SPI serial flash.
> I've seen enough code to initialize the SPI port.
> However, I can't find any sample code that will
> show me how to tx and rx bytes in page mode.
>
> In the AT91_CDROM, I see a file called :
> AT91M55800A-BasicSPI-GHS3_6-2_0.zip
>
> Can I re-use some of the code for the SAM7S64?
> Are the SPI registers the same?
> Thanks >
> Yahoo! Groups Links >
>
routines.
If you're just doing relatively infrequent communications to SEEPROMS
etc then this approach is fine. By bypassing all the SPI stuff you can
make things a lot simpler.
Of course there are times when you really need the throughput of using
the SPI peripheral and then it is worth doing the hard yards.
The other point is that the various seeprom and flash devices have
different command interfaces. You typically need to opull the datasheet
for the device you're using and go with that.
> -----Original Message-----
> From: AT91SAM7@AT91...
> [mailto:AT91SAM7@AT91...] On Behalf Of at91sam7s
> Sent: Thursday, 5 May 2005 11:47 a.m.
> To: AT91SAM7@AT91...
> Subject: [AT91SAM7] SPI help > I want to communicate with a SPI serial flash.
> I've seen enough code to initialize the SPI port.
> However, I can't find any sample code that will
> show me how to tx and rx bytes in page mode.
>
> In the AT91_CDROM, I see a file called :
> AT91M55800A-BasicSPI-GHS3_6-2_0.zip
>
> Can I re-use some of the code for the SAM7S64?
> Are the SPI registers the same?
> Thanks >
> Yahoo! Groups Links >
>
Reply by ●May 5, 20052005-05-05
Using the SPI is straight forward.
Here is a sample of my init code and my read/write code.
You have to write 0xFF in order to Read.
Init:
I am using the CSAAT bit in order to keep CS active for multiple
reads and writes.
INIT()
{
AT91F_SPI_CfgPIO(); // sETUP pio for SPI interface
AT91F_PIO_CfgPullup(AT91C_BASE_PIOA, AT91C_PIO_PA14 |
AT91C_PIO_PA12); // Pull up the CLK PA14 and SDI PA12
AT91F_PMC_EnablePeriphClock(AT91C_BASE_PMC,
1 << AT91C_ID_SPI); // Enable the Peripheral Clock on PA14
//* Reset the SPI 1st
AT91F_SPI_Reset(SPI0);
//*Configure the SPI into Fixed Pheriperhal mode
AT91F_SPI_CfgMode (SPI0, AT91C_SPI_MODFDIS |
AT91C_SPI_PS_FIXED | AT91C_SPI_MSTR);
//*Set SPI_CSR0 for FRAM interface - Set CLK to MCK/4 =
11.9808 MHz - No delays
AT91F_SPI_CfgCs (SPI0, 0, // NPCS0
AT91C_SPI_NCPHA | AT91C_SPI_CSAAT | // Mode 0 & Chip Select
After transfer disabled
(AT91C_SPI_BITS & AT91C_SPI_BITS_8) | // mask & Bits per transfer
(AT91C_SPI_SCBR & (FRAM_CLK_SCBR << 8))); // mask & CLK=MCK/4
//*enable the SPI - NPCS0
AT91F_SPI_Enable(SPI0);
}
Here is my SPI routine
//*------------------------------
----------
//* \fn SPI_Byte
//* \brief transfer character and Receive a character if one is
available
//*------------------------------
----------
char SPI_Byte (const AT91PS_SPI pSPI, char character, unsigned int
cs_number, int last_xfer)
{
unsigned int value_for_cs;
char rx_char;
value_for_cs = (~(1 << cs_number)) & 0xF; //Place a zero among
a 4 ONEs number
// Wait for transmit data register to become available
while ( !(pSPI->SPI_SR & AT91C_SPI_TDRE) );
if (last_xfer)
{
pSPI->SPI_TDR = (value_for_cs << 16) | character |
AT91C_SPI_LASTXFER; // CS# | Character | Last xfer
}
else
{
pSPI->SPI_TDR = (value_for_cs << 16) | character; // CS# |
Character
}
// Wait for receive data register to indicate incoming data
while ( !(pSPI->SPI_SR & AT91C_SPI_RDRF) );
rx_char=((pSPI->SPI_RDR) & 0xff);
return (rx_char);
} --- In AT91SAM7@AT91..., "at91sam7s" <at91sam7s@y...> wrote:
> I want to communicate with a SPI serial flash.
> I've seen enough code to initialize the SPI port.
> However, I can't find any sample code that will
> show me how to tx and rx bytes in page mode.
>
> In the AT91_CDROM, I see a file called :
> AT91M55800A-BasicSPI-GHS3_6-2_0.zip
>
> Can I re-use some of the code for the SAM7S64?
> Are the SPI registers the same?
> Thanks
Here is a sample of my init code and my read/write code.
You have to write 0xFF in order to Read.
Init:
I am using the CSAAT bit in order to keep CS active for multiple
reads and writes.
INIT()
{
AT91F_SPI_CfgPIO(); // sETUP pio for SPI interface
AT91F_PIO_CfgPullup(AT91C_BASE_PIOA, AT91C_PIO_PA14 |
AT91C_PIO_PA12); // Pull up the CLK PA14 and SDI PA12
AT91F_PMC_EnablePeriphClock(AT91C_BASE_PMC,
1 << AT91C_ID_SPI); // Enable the Peripheral Clock on PA14
//* Reset the SPI 1st
AT91F_SPI_Reset(SPI0);
//*Configure the SPI into Fixed Pheriperhal mode
AT91F_SPI_CfgMode (SPI0, AT91C_SPI_MODFDIS |
AT91C_SPI_PS_FIXED | AT91C_SPI_MSTR);
//*Set SPI_CSR0 for FRAM interface - Set CLK to MCK/4 =
11.9808 MHz - No delays
AT91F_SPI_CfgCs (SPI0, 0, // NPCS0
AT91C_SPI_NCPHA | AT91C_SPI_CSAAT | // Mode 0 & Chip Select
After transfer disabled
(AT91C_SPI_BITS & AT91C_SPI_BITS_8) | // mask & Bits per transfer
(AT91C_SPI_SCBR & (FRAM_CLK_SCBR << 8))); // mask & CLK=MCK/4
//*enable the SPI - NPCS0
AT91F_SPI_Enable(SPI0);
}
Here is my SPI routine
//*------------------------------
----------
//* \fn SPI_Byte
//* \brief transfer character and Receive a character if one is
available
//*------------------------------
----------
char SPI_Byte (const AT91PS_SPI pSPI, char character, unsigned int
cs_number, int last_xfer)
{
unsigned int value_for_cs;
char rx_char;
value_for_cs = (~(1 << cs_number)) & 0xF; //Place a zero among
a 4 ONEs number
// Wait for transmit data register to become available
while ( !(pSPI->SPI_SR & AT91C_SPI_TDRE) );
if (last_xfer)
{
pSPI->SPI_TDR = (value_for_cs << 16) | character |
AT91C_SPI_LASTXFER; // CS# | Character | Last xfer
}
else
{
pSPI->SPI_TDR = (value_for_cs << 16) | character; // CS# |
Character
}
// Wait for receive data register to indicate incoming data
while ( !(pSPI->SPI_SR & AT91C_SPI_RDRF) );
rx_char=((pSPI->SPI_RDR) & 0xff);
return (rx_char);
} --- In AT91SAM7@AT91..., "at91sam7s" <at91sam7s@y...> wrote:
> I want to communicate with a SPI serial flash.
> I've seen enough code to initialize the SPI port.
> However, I can't find any sample code that will
> show me how to tx and rx bytes in page mode.
>
> In the AT91_CDROM, I see a file called :
> AT91M55800A-BasicSPI-GHS3_6-2_0.zip
>
> Can I re-use some of the code for the SAM7S64?
> Are the SPI registers the same?
> Thanks
