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strange trouble with multi-slave SPI environment

Started by Pavel Schukin September 9, 2007
Hello, everybody.
I have a board with Analog Devices BlackFin 537 processor tied with
another BF537, several synthesizers and SD Card by SPI interface.
Common MISO,MOSI and all CS pins are provided with pull-up resistors.
The trouble is about SD card programming. It is programmed properly only
if i connect oscilloscope's probe at CLK pin of SD Card connector. I
suppose that probe works like a capacitor in that case.
I checked polariy of clk signal, data to be transmitted. It is OK.
Then i moved out from its slot other BF537 which is slave for current
BF537
and repeated all steps of programming. It was surprising that SD card
response was valid and all transactions was completed succesfully.
I moved in slave BF in its slot and all was bad again.
I work with Visual DSP 4.5, no program are in FLASH of BF (so no boot
process takes place).
I can not understand how the slave BF processor interferes SD
programming.
I try to do all the same on BF EZ-KIT with just SD Card on SPI bus and all
was OK.
I think that trouble is due to many slave devices on SPI bus. But in a
what manner? And what about oscilloscope's probe? What it does with CLK
signal? I'm frustraiting, because board's vendor says my program is wrong,
and all schematic is right. 
Help me if somebody can. I can send schematic and all code.
Pavel Schukin.
"Pavel Schukin" <pav81el@yahoo.com> wrote in message
news:OtCdnUfJheXmNX7bnZ2dnUVZ_sytnZ2d@giganews.com...
> Hello, everybody. > I have a board with Analog Devices BlackFin 537 processor tied with > another BF537, several synthesizers and SD Card by SPI interface. > Common MISO,MOSI and all CS pins are provided with pull-up resistors. > The trouble is about SD card programming. It is programmed properly only > if i connect oscilloscope's probe at CLK pin of SD Card connector. I > suppose that probe works like a capacitor in that case. > I checked polariy of clk signal, data to be transmitted. It is OK. > Then i moved out from its slot other BF537 which is slave for current > BF537 > and repeated all steps of programming. It was surprising that SD card > response was valid and all transactions was completed succesfully. > I moved in slave BF in its slot and all was bad again. > I work with Visual DSP 4.5, no program are in FLASH of BF (so no boot > process takes place). > I can not understand how the slave BF processor interferes SD > programming.
The unbooted BF creates a heavy load on the SPI CLK line. I suppose this is either a BF hardware bug or a software bug in the internal bootloader ROM. I didn't go deeply into the details however I have encountered that kind of problem.
> Help me if somebody can. I can send schematic and all code.
I can solve all of your problems, however this is going to be the business. The contact is at the web site. Vladimir Vassilevsky DSP and Mixed Signal Consultant www.abvolt.com
On 9 Wrz, 10:02, "Pavel Schukin" <pav8...@yahoo.com> wrote:
> Hello, everybody. > I have a board with Analog Devices BlackFin 537 processor tied with > another BF537, several synthesizers and SD Card by SPI interface. > Common MISO,MOSI and all CS pins are provided with pull-up resistors.
I think that serial resistors on SPI lines resolve your problem. Close to driver (CLK, MOSI - master and MISO - slave), put 100R, or more if your clock speed is below 8 MHz. Les