how to read device

[Deepak1]

Dear sir,

I am using MC68HC908JK8 device.But i want to read the device content after programming.

Plz tell me how to read the device.

Deepak

[Ake]

Hi there,

The content of the RAM/Flash EPROM and ROM can easily be read by using the MON08 pin on the chip.

There is one obstacle though, you must know the 8 security bytes.

Many Flash EPROM programmers keep a list of the last security bytes used, and try them one by  one.

But as there are 2 ^ 8 * 8  = 1.8 ^19 combinations, it can be quite a tough job to try them all.

As the MON08 accepts data at 9600 baud, and echoes it back, it takes 2 * (1 + 8 + 1)/9600 =  2 ms just to send the security bytes. So it will take 1.8 ^19 * 2 ms = 3.6 ^16 s = 1140 million years to try all combinations.

As the erased Flash EPROM contains 0xff in all the bytes, and then in all the security bytes, this is the combination to try first.

Regards,

Ake

[peg]

Hi Deepak,

What exactly are you trying to "read".
There are many different answers possible here.

Also what software are you already using? CW?



Message Edited by peg on 2007-12-06 04:42 PM

[Deepak1]

I am using CW & programming language is C.

Actually I mean to say is,

I have cyclone pro stand alone programmer,After programming the chip i want to read the device.Also i am having P & E usb multilink.

[peg]

Hi,
If you have just programmed the device and have the source code, why do you want to read it back out of the chip?
You can go into expert programmer mode and perform a verify, if it verifies OK then you know whats in there.
If you really want to read it out then use Upload Module in the expert programming mode and this will save the whole contents of the flash into a s19 file on your pc.

[Deepak1]

Thanks for replying,

The reason for asking is,

We found some Units (i.e. Our product) not working conditions at the customer end.But before dispatching we have tested & it was working ok as per spect.

But after some days my customer send back to us.So we made analysis and conclude that the fault in IC,So we removed it and checked with our standard board.Found not working.

Then we again programmed that IC & still it is working fine.

So i want to know that whether the IC content is erased that time.

This is the reason for reading the IC.

[Nabla69]

Hello,

If the device is erased, you can read its content with any programmer and using only $FF for the security bytes.

Does your device make storage of values in Flash/Emulated E²PROM in circuit ?
It is possible that the routine used is incorrect and that, refreshing the COP, the Vector table is erased.
That is a common mistake.

Cheers,
Alban.

[bigmac]

Hello,

The matter alluded to by Alban, as a possible cause of vectors becoming erased, is due to problematic ROM based code that may be called to erase a single flash page.  However, the JK8 device does not appear to be one of the devices that exhibit this "page erase issue".  Further details can be found within AN1831.

Regards,

Mac

[Nabla69]

Hello,

I was actually thinking about user code, but it's true that some old masks had this error embedded.
Another common reason for a code to get erased is if the programming was not done with proper timing.
But maybe the code is not erased. Have you tried to read it back with its initial security bytes (=the one from the software you programmed) ?

Alban.

[peg]

Hi,
More details on how to read here.