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Hi I am using an SPI port in master mode and have the following routine to transmit/receive bytes from the slave. far byte spi_RFTxRx (byte tda, byte *rda) /* spi_RFTxRx: ** ** Graham, Issue 1.0, 15 Dec 2003 ** ** Transmits and receives data from RF Module */ { while (!(SPI1SR & SPTEF)); // No room in transmit buffer; SPI1DR = tda; // Send data while (!(SPI1SR & SPIF)); // Rx not yet complete *rda = SPI1DR; // Get data return (OK); } This routine has worked fine for months, I have just added some functionality that checks the status of the slave device during POR. The routine above gets called from a higher level routine which works fine in every other circumstance. The problem I have is, the function is called 4 times fine then the 5th time the SPIF flag never gets set to 1 and my routine hangs intermittently, say 1 out of 5 POR's. I have checked my signals and I get all eight clock pulses as expected but no SPIF flag on completion. I have checked the errata for the chip I am using but have found nothing indicating such a problem. Any help would be greatly appreciated. Cheers Graham ********************************************************************** This message contains confidential information and is intended only for the individual named. If you are not the named addressee you should not disseminate, distribute or copy this e-mail. Please notify the sender immediately by e-mail if you have received this e-mail by mistake and delete this e-mail from your system. Although BERU F1 SYSTEMS believe this e-mail and any attachments are free of any virus or other defect which may affect a computer, it is the responsibility of the recipient to ensure that it is virus free and BERU F1 SYSTEMS do not accept any responsibility for any loss or damage arising in any way from its use. This footnote confirms that this email message has been swept by MAIL Sweeper. ********************************************************************** |
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SPI SPIF not getting set (MC9S12DP256C)
Started by ●May 17, 2004
Reply by ●May 19, 20042004-05-19
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I was having endless amounts of random problems with my SPI routines a few months ago(on a MC9S12DJ128B). I finally got a hold of the right person at motorola and he gave me this suggestion: SPI1CR1_SPE = 1; //enable SPI __asm NOP; __asm NOP; __asm NOP; test=SPI1SR; test=SPI1DR; The NOPs are there because he said he *always* puts them their and never has had a problem. I'm willing to gamble 3 cycles on that :^) He also reads both the SR and DR to ensure flags get cleared. As soon as I did this, the random problems I was having disappeared. Another idea if you don't want to risk a lock up(and aren't using the COP) would be to stick a counter in the while() test. Of course, if your slave device not working causes death and destruction, it might not be a good idea! I just defined a var int count= 0xFFFF; then made my loop as follows: while( !SPI1SR_SPTEF && count) { __asm NOP; //WAIT for the transmitter empty flag count--; } The NOP's optional, but it does give me more clock cycles to wait before I just give up on the transfer. --- In , Graham Tricker <Graham.Tricker@F...> wrote: > Hi > > I am using an SPI port in master mode and have the following routine to > transmit/receive bytes from the slave. > > far byte spi_RFTxRx (byte tda, byte *rda) > > /* spi_RFTxRx: > ** > ** Graham, Issue 1.0, 15 Dec 2003 > ** > ** Transmits and receives data from RF Module > */ > > { > > while (!(SPI1SR & SPTEF)); // No room in > transmit buffer; > SPI1DR = tda; // Send data > > while (!(SPI1SR & SPIF)); // Rx not yet > complete > *rda = SPI1DR; // Get data > > return (OK); > > } > > This routine has worked fine for months, I have just added some > functionality that checks the status of the slave device during POR. The > routine above gets called from a higher level routine which works fine in > every other circumstance. The problem I have is, the function is called 4 > times fine then the 5th time the SPIF flag never gets set to 1 and my > routine hangs intermittently, say 1 out of 5 POR's. > > I have checked my signals and I get all eight clock pulses as expected but > no SPIF flag on completion. I have checked the errata for the chip I am > using but have found nothing indicating such a problem. > > Any help would be greatly appreciated. > > Cheers > > Graham > ********************************************************************* * > This message contains confidential information and is intended only for the individual named. If you are not the named addressee you should not disseminate, distribute or copy this e-mail. Please notify the sender immediately by e-mail if you have received this e- mail by mistake and delete this e-mail from your system. > Although BERU F1 SYSTEMS believe this e-mail and any attachments are free of any virus or other defect which may affect a computer, it is the responsibility of the recipient to ensure that it is virus free and BERU F1 SYSTEMS do not accept any responsibility for any loss or damage arising in any way from its use. > This footnote confirms that this email message has been swept by MAIL Sweeper. > ********************************************************************* * |
