|
You may want to bear in mind that the Atmel part has two SPI clock modes
SPI Mode 1 and SPI Mode 3 relating to CPOL and CPHA this is outline on page 3 of the Atmel datasheet Read Commands. Graham Tricker - Software Engineer BERU F1 Systems Technical Centre Oven Road Diss Norfolk IP22 4ER Tel: 01379 646227 Fax: 01379 646900 -----Original Message----- From: Edward Karpicz [mailto:] Sent: 01 June 2004 14:45 To: Subject: Re: [68HC12] Re: Problem with SPI ----- Original Message ----- From: "manekb2000" To: <> Sent: Tuesday, June 01, 2004 3:25 PM Subject: [68HC12] Re: Problem with SPI > Hi > > I still have a problem with communications S12A64 with AT45DB041B. > After init: [skip] > I read status register: > while(!SPTEF_0); > SPI0DR = 0xD7; > while(!SPIF_0); > status=SPI0DR; > > First value of status register is wrong - 0xff, the next is o.k. - > 0x9c. I don't understand why? My speculations: First time SPIF was set - AT45 had your 0xD7 shifted in and was ready to shift out status byte on next write to SPIDR. > When I read memory (continuous array read): > //write opcode > while(!SPTEF_0); > SPI0DR = 0xE8; > //write adress 0 and don't care bytes > for(i=0;i<7;i++) > { > while(!SPTEF_0); > SPI0DR = 0x00; > } S12SPI is double buffered. This means - if master mode spi transmitter is idle (no SCK pulses) - SPTEF will get set almost immediately after write to SPIDR. And this means your for loop only buffered 7 zeroes for transmission. 6th zero is currently being transmitted and 7th is sheduled to be transmitted as soon as possible. > //read byte from memory > while(!SPIF_0); SPIF gets set after transfer is complete. Last time SPI module was trying to set SPIF - was after 6th zero was transferred. > *data++ = SPI0DR; Here you are trying to read from SPI0DR what AT45xx was shifting on 6th zero OR, if SCK clock is quite fast and you have interrupts enabled - you may be trying to read what ATxx was shifting on 7th zero. > first reading byte is the same value that status register - 0x9c, > but next reading stop at while(!SPIF_0); You have to write to SPIDR to receive something from slave device. CPU didn't hang on first while(!SPIF) because you were sending zeroes and didn't clear SPIF. Try to lower SCK clock - and CPU should be able to read 2 bytes before hanging on while(!SPIF). > > Where is error? Can somebody help me? Try to replace all SPTEFs with SPIFs, add missing writes to SPIDR, read erratas... Edward > Regards > Mariusz --------------------To learn more about Motorola Microcontrollers, please visit http://www.motorola.com/mcu <http://www.motorola.com/mcu> o learn more about Motorola Microcontrollers, please visit http://www.motorola.com/mcu <http://www.motorola.com/mcu <http://rd.yahoo.com/SIG9eeve3k/M)5196.4901138.6071305.3001176/D=groups /S06554205:HM/EXP86183947/A!28215/R=0/SIGse96mf6/*http://companio n.yahoo.com> click here <http://us.adserver.yahoo.com/l?M)5196.4901138.6071305.3001176/D=groups/S= :HM/A!28215/rand0636765> _____ > Service. ********************************************************************** 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. ********************************************************************** |
|
|
Re: Problem with SPI
Started by ●June 3, 2003
Reply by ●June 1, 20042004-06-01
Reply by ●June 2, 20042004-06-02
|
>You may want to bear in mind that the Atmel part has two SPI clock >modes SPI >Mode 1 and SPI Mode 3 relating to CPOL and CPHA this is outline on >page 3 of the Atmel datasheet Read Commands. Yes, I use Mode 0 (CPOL=0, CPHA=0) - AT45 work at this mode. |
Reply by ●June 2, 20042004-06-02
|
> > First value of status register is wrong - 0xff, the next > is o.k. - > > 0x9c. I don't understand why? > > My speculations: First time SPIF was set - AT45 had your > 0xD7 shifted in and was ready to shift out > status byte on next write to SPIDR. ... How I should read received byte? If I write to SPIDR new byte, it will be a new command and I can rewrite receiwed byte. How I can do it? When I add write command befor reading, program don't hanging on while (!SPIF), but read only one value... I stell can't read status on the first read, second read is ok, but reading memory received only previous value from SPIDR (status register). > Try to replace all SPTEFs with SPIFs, add missing writes > to SPIDR, read erratas... Where I can find this errata? On the Motorola site I didn't found errata to SPI. Thanx Mariusz |
Reply by ●June 2, 20042004-06-02
|
Below is my transmit/receive routine for the AT45, it is a pretty generic routine that I have used for a few SPI interfaces. far byte spi_FlashTxRx (byte tda) /* spi_FlashTxRx: ** ** Graham, Issue 1.0, 17 Sept 2003 ** ** Transmits and receives data from flash */ { byte rda; while (!(SPI0SR & SPTEF)); // No room in transmit buffer; SPI0DR = tda; // Send data while (!(SPI0SR & SPIF)); // Rx not yet complete rda = SPI0DR; // Get data return rda; } you can use this to transmit and receive as below. spi_FlashTxRx(opcode); // Transmit OpCode *rda = spi_FlashTxRx(0); // Received data I use this one routine to do all the SPI transmit and receive stuff and have written higher level functions such as RdFlashMem () and WrFlashMem () which call this routine. Hope this helps. Graham -----Original Message----- From: manekb2000 [mailto:] Sent: 02 June 2004 13:47 To: Subject: [68HC12] Re: Problem with SPI > > First value of status register is wrong - 0xff, the next > is o.k. - > > 0x9c. I don't understand why? > > My speculations: First time SPIF was set - AT45 had your > 0xD7 shifted in and was ready to shift out > status byte on next write to SPIDR. ... How I should read received byte? If I write to SPIDR new byte, it will be a new command and I can rewrite receiwed byte. How I can do it? When I add write command befor reading, program don't hanging on while (!SPIF), but read only one value... I stell can't read status on the first read, second read is ok, but reading memory received only previous value from SPIDR (status register). > Try to replace all SPTEFs with SPIFs, add missing writes > to SPIDR, read erratas... Where I can find this errata? On the Motorola site I didn't found errata to SPI. Thanx Mariusz --------------------To learn more about Motorola Microcontrollers, please visit http://www.motorola.com/mcu <http://www.motorola.com/mcu> o learn more about Motorola Microcontrollers, please visit http://www.motorola.com/mcu <http://www.motorola.com/mcu <http://rd.yahoo.com/SIG94r8akh/M)5196.4901138.6071305.3001176/D=groups /S06554205:HM/EXP86266914/A!28215/R=0/SIGse96mf6/*http://companio n.yahoo.com> click here <http://us.adserver.yahoo.com/l?M)5196.4901138.6071305.3001176/D=groups/S= :HM/A!28215/randG5119664> _____ > Service. ********************************************************************** 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. ********************************************************************** |
|
|
