MCF5234: Cannot Program last Sector of Am29DL163DT Flash on CustomBoard

[sirlenzelot]

Hi All.

We have a Custom Board (Rev1) with the Am29DL163DT Flash and encounter the following problem:

We cannot program the last two Sectors of the Flash (Offset 0x1FC000 and 0x1FE000). Any other Sector can be programmed.

The board is designed using freescale's EVB-example.

When using the original 5235 EVB everything goes. (Flash here is Am29PL160CB)

Flashing a newer Custom Board (Rev 2) with the S29GL064 works fine.

Did someone encounter similar problems with Flashs or can give some hints.

Thanks in advance.

vy 73

Dirk

[TomE]

> Am29DL163DT

That part looks to be fairly ancient. I haven't been able to find an on-line data sheet for it.

The summary says it is a "sectored, asymmetric, boot-block-at-top" FLASH chip.

You're trying to program the Boot Block. These blocks are meant to hold the Bootstrap, so they are protected against being overwritten.

A similar chip, the AM29F160D, has a "#WP" pin. If this is driven low, the boot block is unconditionally protected.

I suspect  there's a jumper of some sort on the board that allows the #WE pin to be pulled high to allow the Boot Block to be programmed.

The other chips you're using don't have these special boot blocks, or are set up so programming them is enabled.

It's a strange chip choice for your board. The MCF chips all boot from low addresses. Why does your design have a high-address boot-block chip? Was someone using up existing stock of parts that were used on a board with a chip that boots from high addresses?

Tom

[sirlenzelot]

Hi Tom,

thanks for your answer.

The chip is fairly old, that's correct. It resides on older boards only. There seems to be a little error in the schematic and because of that the bootblocks are always locked. No one noticed this because we did not have the need to write the last block, until now.

The "strange choice" was done before my time at the company. For the next redesign there will be some correction. :smileywink:

vy 73

Dirk