Hi all,

I am using m25p64 SPI Flash(ST) in my project. Shortly, I am connecting m25p64 with ADSP-BF532
DSP and I am booting the linux kernel from SPI Flash(m25p64), but sometimes I am facing a
communication problem so I get Bad Data Crc message. I have searched and made many tests,
finally I realised that the problem is about SCK pin of m25p64. I had put 100K resistor between
SCK and GND like reference designs in datasheets(and I also put 4K7 between Select pin and Vcc
) but I found that it didn't work, I tried many resistor values but it was useless. After that
I put 33pf capacitance on SCK pin instead of 100K resistor and it worked. It has been working
for 2 months, It seems this is an exact solution but I can't explain WHY?. What is your
comments? 

Thank you in advance

------------------------------------

Probably clk signal overshoot/undershoot so that sometimes a extra clock 
edge is detected by the M25P64. A smaller than 100K resistor probably 
also would have do the job.

Regards,

Javier, EA1CRB

e...@yahoo.com escribió:
>
> Hi all,
>
> I am using m25p64 SPI Flash(ST) in my project. Shortly, I am 
> connecting m25p64 with ADSP-BF532 DSP and I am booting the linux 
> kernel from SPI Flash(m25p64), but sometimes I am facing a 
> communication problem so I get Bad Data Crc message. I have searched 
> and made many tests, finally I realised that the problem is about SCK 
> pin of m25p64. I had put 100K resistor between SCK and GND like 
> reference designs in datasheets(and I also put 4K7 between Select pin 
> and Vcc ) but I found that it didn't work, I tried many resistor 
> values but it was useless. After that I put 33pf capacitance on SCK 
> pin instead of 100K resistor and it worked. It has been working for 2 
> months, It seems this is an exact solution but I can't explain WHY?. 
> What is your comments?
>
> Thank you in advance
>
>  
------------------------------------

Hi,

Have you checked out EE-240 at ADI's website?  It describes the booting
process (for the BF533 family) and interface guidelines for SPI memory.

Best regards,

George Kadziolka

Kaztek Systems

www.kaztek.com <http://www.kaztek.com/>

  _____  

From: a...@yahoogroups.com [mailto:a...@yahoogroups.com] On Behalf Of
e...@yahoo.com
Sent: Tuesday, March 25, 2008 3:28 AM
To: a...@yahoogroups.com
Subject: [adsp] SPI Communication problem ADSP-BF532

Hi all,

I am using m25p64 SPI Flash(ST) in my project. Shortly, I am connecting
m25p64 with ADSP-BF532 DSP and I am booting the linux kernel from SPI
Flash(m25p64), but sometimes I am facing a communication problem so I get
Bad Data Crc message. I have searched and made many tests, finally I
realised that the problem is about SCK pin of m25p64. I had put 100K
resistor between SCK and GND like reference designs in datasheets(and I also
put 4K7 between Select pin and Vcc ) but I found that it didn't work, I
tried many resistor values but it was useless. After that I put 33pf
capacitance on SCK pin instead of 100K resistor and it worked. It has been
working for 2 months, It seems this is an exact solution but I can't explain
WHY?. What is your comments? 

Thank you in advance

e...@yahoo.com wrote:
>
> Hi all,
>
> I am using m25p64 SPI Flash(ST) in my project. Shortly, I am 
> connecting m25p64 with ADSP-BF532 DSP and I am booting the linux 
> kernel from SPI Flash(m25p64), but sometimes I am facing a 
> communication problem so I get Bad Data Crc message. I have searched 
> and made many tests, finally I realised that the problem is about SCK 
> pin of m25p64. I had put 100K resistor between SCK and GND like 
> reference designs in datasheets(and I also put 4K7 between Select pin 
> and Vcc ) but I found that it didn't work, I tried many resistor 
> values but it was useless. After that I put 33pf capacitance on SCK 
> pin instead of 100K resistor and it worked. It has been working for 2 
> months, It seems this is an exact solution but I can't explain WHY?. 
> What is your comments?
>

I think the problem might be ringing. This would be likely if the clk 
line is long. I would add a 33 ohm series terminator located very near 
the Blackfin (driving side). I generally use a small network and also 
use series terminators for MOSI and SS as well. You can do the same 
thing on MISO near the Flash.

The SCK is probably the only one that is important. I also use strong 
pullups (and not pulldowns), anything from 3k3 to 10k

This is precisely the configuration we use on our dspFlash Blackfin & 
Sharc programmer (uses BF-532 & serial flash) as well as countless Sharc 
designs with serial flash and they all work fine.

Al Clark
Danville Signal Processing, Inc.

------------------------------------