Topic : How to enable/disable readout protection in Rflahser for STR7 device?

Forum : ARM

Original Post
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January 10, 2008 - 11:30am
Guest

usign RLink with Rflahser and select STR7,
but can not see any readout protection selection menu? (only write protection available)
and I connect a target with protection, even erase done, the status of the IC still protected and can not be read!
Replies
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January 10, 2008 - 11:48am
Raisonance Support Team

Hi,

The STR7 readout protection is designed in a such a way that it can be set by JTAG or by the application itself, but it can only be removed by the application, not by JTAG.

This means that RLink has no way to remove it, and this is why we did not give the option to set it. To avoid unwanted setting of a protection that could not be removed.

So the read-out protection must be completely handled (both set and removed) by the application. If your part is protected and the application programmed inside it does not allow to remove the protection, I'm afraid there is no way to reprogram it. I think even ST cannot help on this, but it might be worth asking them... ;)

Are you using a demonstration board, or a board that has been working in the past? If you are using a new board or a prototype, then please note that some connection errors might be interpreted by the RLink as a protection that is set. So the first thing to do is to make sure that your part is really protected. If it was working before and then after programming something it stopped working, or if you have other identical boards that you can work with, then probably we can say that it is indeed protected. Otherwise, I suggest you do some tests... Do you have another identical board with a new, blank part? (for testing the connection) Does the board design allow you to remove the chip from the board and place it on another board that you know is working? (to test the part with connections that are known to be correct)

Best Regards,

Vincent
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January 14, 2008 - 3:31pm
Guest

really ?? so if a device is protected against readout, it can not be ERASED and reused in the application or board ??
that cant be true !
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January 14, 2008 - 4:48pm
Raisonance Support Team

Hi,

Yes, it can be erased, but only if it is previously unprotected, which can only be done by the application itself. (and only from the Flash, not from the RAM)

So if you protect a part with a blank flash (this cannot happen with our tools) or with an application that never unprotects, then you can indeed throw the chip away. Surprising but true.

The read-out protection completely disables the hardware part of the chip that handles JTAG, which is the only way for RLink to communicate with the chip. This is why RLink cannot make the difference between a protected part and a wrong connection. It just gets no answer in both cases!

Check the "STR7 family Flash Programming Reference Manual" from ST for more information.

Best Regards,

Vincent
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January 15, 2008 - 12:11pm
Guest

wow cool :-)
but maybe "The read-out protection" should have been called "JTAG disable, futher R/W is impossible"
so no people do this again, do people read the manual ??
I think only when they have an actual problem, haha
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January 15, 2008 - 2:11pm
Raisonance Support Team

Hi,

Well, in the doc, it is called "debug protection".

Here is what the doc says:

If bit XXX of register XXX is programmed at 0, the device becomes Debug protected:
debug features and JTAG pins are disabled.

And this feature is not documented anywhere else than in this manual, and the JTAG tools do not allow to set the protection, which means that unless you read the manual, you have no way to set the protection. (and you probably don't even know that it only exists.)

So it should be all right.

Best Regards,

Vincent