MSP430G2402: Programming FLASH memory as EEPROM

Hi Maria Angela,

When saying "Flash is no longer protected" are you referring to the Flash memory no longer being locked?

Please be aware of the following when writing to Info Memory segments:

The Info A is protected and locked by the LOCKA bit in FCTL3 register; the LOCK bit cannot unlock Info A but the other way around LOCKA will unlock the whole Flash memory, both the Info segements and the main memory. So if you unlock InfoA and write to it your main memory will also be unlocked. Unlocking the Flash using LOCK will unlock all Flash memory except InfoA.

For details see the MSP430x2xx Family User's Guide section 7 Flash Memory Controller.

In case your program code fits into Info A you could that way further protect your program code from being accidentally accessed when writing to other parts of the Flash memory.

Let me know if this answered your question.

Best regards,

Britta

In Info A segment of 2xx flash devices are stored factory calibrated data (DCO, ADC...), and because of this there is LOCKA.

Good morning everybody and thanks a lot for your answers!!

In order to be much specific: I use the SEGMENT D of the Info Memory as an EEPROM and, to do that, I set and clear the LOCK bit as it is described in TI MSP430x2xyz familly's datasheet (section 7 as Britta mentioned in her post).

After erasing D segment I write on it my data so that I can store them also when the machine is shut off. To do this I use the same procedure described in TI datasheet (chapter 7, paragraph 3)

I think this is the correct procedure to erase and write on my D segment, isn't it?

So, programming the FLASH in this way, is it possible that the Flash memory is no longer being lock?

I really appreciate any answer to this particular question.

Thanks a lot & Best Regards

Maria Angela

Hi Maria Angela,

as you said you are erasing and writing to Segment D according to the User's Guide it should be fine.

As said before, while you erase and write to Segment D the whole Flash is unlocked (except for Info Memory A) until your erase/write operation is done and you lock the Flash again.

If you say Flash memory, are you specifically talking about the main meory? When do you see protection bit unlocked without expecting it to be unlocked?

Best regards,
Britta

Hi Britta!

Thank you very much for your answer. It really clarify me what is the root of the problem.

Yes, when I say Flash Memory I'm talking about the Flash Main memory of the processsor.

The issue I highlight is the same we were talking about Uwe in the last few weeks offline: the address stored in RESET vector location changes randomly.

Luigi, my boss, thinks that if while the flash is unloked and any kind of electrostatic disturb would coming, it is this that causes the wrong re-programming of the reset vector.

In this scenario which is the best way protect the Flash memory's part reserved to VECTORS from accidentally programming?

  Thanks a Lot & Best Regards

Maria Angela