| Author | beginning argument ( Replies received: 1 ) |
| aa |
 Posted 27-03-2008 at 22:20 |
Registered on :
03-27-2009
Messages : 3
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Hello,
I use a UPSD3354DV-40u6 and have a problem with reading the internal SRAM.
After testing several pcb boards the result is that I have boards that read
corrupt data from the internal SRAM. After debugging I have seen that a wrong board
has a "bad signal" at the databus when reading at an adres in SRAM. With "bad signal" I
mean that it is not a nice "1" but a slow rising signal from "0" to "1" like loading a capacitor.
Other external busdrivers can drive the bus and are tri-state at the moment the SRAM is reading.
(seen with a scoop that triggerd on the \RD pin an looking at MCUAD0 (multiplexed databus 0)).
After some testing the board is working fine and it have a good signal.
Please let me know if you have some tips or suggestions to solve this problem.
Best regards,
André
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| aa |
 Posted 28-03-2008 at 20:13 |
Registered on :
03-27-2009
Messages : 3
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Hello all,
The problem is solved. The reasen was that the battery voltage (PC2) was sometime above the Vdd so thhe SRAM goes in protection mode.
Best regards,
André
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reading bad internal SRAM data