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[51] SRAM WR pin is not anabled

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naalald

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Hello,

I'm working with 80c32 micro and I have a AM29F010 Flash and a HM6264 SRAM. I have this problem that when I turn on the circuit, the SRAM WR pin which comes from micro WR pin, is not enabled at all.

What is the problem?

Thank you.
 

Hi,

There are two primary causes: hardware or software.

* hardware: not wired correctly
* software: the software you use is not accessing the SRAM

How can we know without useful information?

Klaus
 

KlausST said:
Hi,

There are two primary causes: hardware or software.

* hardware: not wired correctly
* software: the software you use is not accessing the SRAM

How can we know without useful information?

Klaus
Click to expand...

Thanks Klaus,

Hardware I'm pretty sure about wiring, cuz at the startup the SRAM WR pin gets a few enable pulses but after that I don't see anything.
About the software: I have a FLASH which has the program on it cuz 80c32 is ROMless. At the startup some instructions are loaded from FLASH to micro and I can see this clearly. After that the SRAM should start to get the rest of the program, but this doesn't happen since its WR pin is not enabled by micro at all.

FYI, I have not written the program and I'm just testing it and I don't have the source code. The only thing I have is the HEX code.
 

It seems the initial code (the bootloader) is being loaded but from there it either isn't configuring the SRAM interface pins or it isn't starting the program loader for some reason. My first suspicion is a software problem but without the source code it would be difficult to track down.

Assuming the SRAM bootloader is intact, the only other likely cause is the wiring between the 80C32 and SRAM is wrong, not necessarily defective but the pins are swapped over.

A bootloader will almost certainly be written in machine code so disassembling it to verify its integrity should be fairly easy. The code must execute from the reset address so the entry point should be obvious.

Brian.
 

I would assume that the code is executed out of the flash memory rather moved to RAM. In this case, the RAM #WR signal won't be pulled low before a write access to XRAM memory happens in the code.

To allow usage of the RAM as code memory, it must be read selected by #PSEN with some kind of banking logic switching between flash and RAM. Not impossible but rather unusual.

If you want to discuss this in detail, you should provide a schematic of actual flash and RAM connections to 8032.
 

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