Hello everyone,
I got some AT89C51RD2 chips that had their original bootloaders overwritten. Now I can't use FLIP to reprogram them.
AFAIK, now I need a parallel programmer to erase the chips and reflash the original bootloader.
So, I have two questions:
1) Where can I get the bootloader hex file for this specific chip?
2) Which parallel programmer should I use? I can build it if I can get the schematics.
Thank you all in advance!
Eduardo
find someone with a programmer if RC2 works (or the 'youngest version of an Atmel chip'), great, if not you have lost the chip anyway
Good idea, Erik! If nothing else works, I'll certainly do that.
However, following your last post, I went after some older datasheets, the ones that still bring information on parallel programming, and see this info I found on AT89C51RC, quite interesting:
"Chip Erase Sequence: Before the AT89C51RC can be reprogrammed, a Chip Erase operation needs to be performed. To erase the contents of the AT89C51RC, follow this sequence: 1. Raise VCC to 6.5V. 2. Pulse ALE/PROG once (duration of 200 ns - 500 ns) and wait for 150 ms. 3. Power VCC down and up to 6.5V. 4. Pulse ALE/PROG once (duration of 200 ns - 500 ns) and wait for 150 ms. 5. Power VCC down and up."
This is quite easy to implement. And it may work, according to the AT89C51RD2 datasheet:
"Only a full chip erase in parallel mode (using a programmer) or ISP command can reset the soft- ware security bits."
So, it seems all I need to do is to build a simple circuit to feed 6.5V to Vcc thru a transistor, and write some simple code for a working MCU to signal the transistor and ALE at the correct timings.
Since this won't take a long time to implement, I'll give it a shot. What do you think about this possible solution?
Thanks for the help!
That's what eBay, or such, are good for, you can find someone who already has a programmer, but needs devices for some legacy product/project.
The other reason build-your-own prom programmers disappeared is the cheapness of reasonably professional alternatives, and the fact the market for antiquated devices keeps shrinking.
Indeed, eBay is a good way to end this history if all else fails. Anyone interested can have all my 22 chips for $30.00 plus shipping.
I'm now waiting for a reply from Atmel's support. This is my last try. I want to confirm the correct procedure for a complete AT89C51RD2 erase. I can't find any document on the subject for this specific chip.