Unable to erase the Security Bits in 89C51RC+

[Mohit Gupta]

Hello,
I am using phillips 89C51RC+.  I am able to connect the flash magic to my target board.  I am not able to reset the security bits.  I have tried erasing the chip through flash magic as well as parallel programmer.  The chip gets fully erased.  I am able to program the chip through parallel programmer but flash magic doesn't does so.  Whenever I read the status of the security bits through the flash magic, I see that all of the security bits are set.

I have tried through flashmagic version 1.61 and version 1.75
Please advise me how to program the chip and reset the security bits.

Regards,

Mohit

[Andy Ayre]

It is not possible to erase (reset) the security bits using ISP on the Rx+ family of devices. You can only set them.

However, you should be able to erase the security bits using a parallel programmer. If that does not appear to be working then I suggest you contact the manufacturer of your parallel programmer to find out how to do it. Maybe there is a seperate erase function in the programmer software for the security bits.

[Mohit Gupta]

Hi Andrew,

Using the parallel programmer, I am able to erase the chip and then reprogram it.  This is possible only if the security bits are reset when I erase the chip. Isn't it so?  The programmer doesnot has any specific feature to reset the security bits only.

Mohit

[Andy Ayre]

Try erasing the device, and ensure the status byte is set to a non-zero value. Then without programming use Flash Magic to read the security bits. What are they set to?

If they are erased then for some reason your parallel programmer is setting the security bits automatically after programming. Maybe there is an option somewhere to stop that happening?

If they are still set, then there must be another option somewhere in the programmer software to erase them. I would then contact the manufacturer to find out how to do it.

I would expect the security bits to be ignored when erasing the device using a parallel programmer, as you are erasing all data in the device protected by the security bits. I would also expect a full device erase using a parallel programmer to erase the security bits as well.

[phil]

I have a similar problem when trying to program a T89C51RD2 . When I perform a full device erase and then read the security bits they are shown to be set. Using WinISP 2.28 allows me to erase and program the device without any problems.

[Andy Ayre]

Phil:

If ALL the following are true:

 - the security bits are shown as being set in the Read Security Bits dialog window

  - you are using the latest version of Flash Magic

  - you are really using a Philips P89C51RD2 rather than a Temic/Atmel T89C51RD2

then please contact me to help me debug the problem.

If you are using the Temic/Atmel device (part name starts with a 'T'), then it is unsupported with Flash Magic and there is every possibility that strange things may occur. I suggest you use Flip from Atmel for that device.



Post Edited (05-20-03 08:08)

[Mohit Gupta]

Hi Andy,

I am using Phillips 89C51RC+ only.  I have tried using it with the latest FlashMagic version 1.75.  I even tried this with 3-4 new chips.  I directly interfaced the new chip with the flash magic and read the security bits.  All the security bits are shown as 'Set'.

The chips are programmable through the parallel programmer but not through flash magic.

I have grounded the PSEN pin temporarily, EA pin is tied to +5V.  Pin 2.6 and 2.7 are pulled up through 4.7 resistance and ALE is left floating.

Regards,

Mohit Gupta

[Mohit Gupta]

Hi Andy,

I tried the same things with phillips P89C51RD2HBP.  I was able to program the chip.  There appears to be some problem with either the 89C51RC+ chip or the Flash Magic Software that it doesnot take the security bits of 89C51RC+ correctly.

Regards,

Mohit

[Andy Ayre]

So you took a brand new device, that has never been programmed, either by ISP or in a Parallel Programmer, started Flash Magic, and all three checkboxes became checked? If so what happens if you then choose Read Security Bits... from the ISP menu? What does it say?

[Mohit Gupta]

When the brand new 89C51RC+ were read by the Flash Magic, it showed all the three security bits as set.

[Mohit Gupta]

IS PHILLIPS 89c51rc+ not programmable with flash magic?

[Andy Ayre]

Yes it is supported and is being used successfully by many people around the world.

Please follow the steps in the Last Resort section of Flash Magic Application Note 4. I want you to perform two ISP operations: read device signature and read security bits. Thanks.