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
I can build it if I can get the schematics. don't bet on it, there is tons of 'know how' in making parallel programmers. In the pre-ISP days, the "why does the programmer I copied on my kitchen table not work" was, almost, a weekly occurance.
Thanks for the reply, Erik.
I just meant even schematics would help, if a commercial product is not available.
In fact, I'm still rather confused about this: I'm not even 100% sure these MCUs had their bootloaders destroyed. I just know the parts have some software already burned in them (I can see serial output at hyperterminal, sent by this software), and I can't put the part in bootloader mode to use with FLIP.
So, I suppose the bootloader isn't there anymore, and must be restored.
Well, any help is greatly appreciated, thanks,
I did some more research, and I'm convinced all I need is a way to reset the lock bits on my AT89C51RD2 chips.
But it's extremely difficult to find a not-so-expensive parallel programmer that fully supports this part. All programmers in the $100.00 range I found so far support only up to AT89C51RC.
So, my new question: is it possible to use a AT89C51RC programmer to only reset the lock bits of a AT89C51RD2? After that, I can do the actual programming using the UART / ISP procedure.
Thanks in advance,
several years ago, the manufacturers stopped publishing parallel programming info because their support was overloaded by requests from "kitchen table programmer makers" and I have anecdotal evidence that a major issue was that the chips were, in one or more instances, not programmed 'fully' i.e. they lost the programming after a while and, of course, the complaint was "your chip" not "my 'programmer'
my recommendation is throw away the $2 chip, instead of spending a lot of time and money trying to recover it.
Erik
Erik, that explains a lot. Now I understand why older datasheets are so detailed in this area, and the current ones don't even touch the subject.
And that also explains why projects like Willem and others are abandoned since 2005 or so.
Thanks anyway. I think you're right about throwing away the chips, but I have 22 units of them, that hurts!
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.