Pic to Pic Firmware upgrade

[BobP]

Hi,

Have used several telecommunication products that upgraded it's firmware by radio. It’s not as straightforward as it seems.

It should not be too difficult to transmit the firmware to the receiving GSM as internal error correction should keep errors to a minimum. But a RF link to the reciving PIC may give problems? The bigger the firmware the harder it will be. External memory will most likely be required. The biggest problem is getting an accurate copy of the firmware over to the receiving PIC. One company sends the firmware twice and compared it for errors. The firmware must be stored and checked before loading into the PIC's own memory. Remember any corruption of the transmitted firmware when loaded and run could ‘lock’ the receiving PIC. Necessitating a visit to do a hardwire re-programming.

One system I had to use solved all these problems but forgot to allow for the phone connection 'dropping' in mid transfer. The result was a trip on site and reseting and reloading software.

As has been said previously a modified version of a bootloader followed by a reset should do the job.

Bob

[rjones2102]

Thanks guys,

OK, I already figured some external memory might be necessary to fit the code into prior to the actual reprogramming of remote Pic.

The GPRS modem will have a TCP/IP stack so the file will be FTPed across air. So, that will deal with the data integrity of the firmware that reaches the actual hardwired network.

When sending to the ultimate destination transmitting it twice and doing a compare sounds a good idea. It might end up more than twice but as long as it doesn't loose integrity that will be fine.

Using a bootloader should eliminate the problem of failed firmware upgrade requiring a trip to 'shop' as the code will not be loaded unless it has been received error free providing the bootloader has the smarts.

I guess what I need is bootloader code for a Pic. I am not clever enough (yet!) to write it so has anyone got any starting points for me? I bet someone has written one even if not in the PBP world. Hummm, a wider google search needed I think. I will post anything I find as this thread could be interesting as it develops.

Thanks

Rich

[Ioannis]

Please note that if you are going to use a bootloader, your precious hex code will be free for anyone to copy it! There can not be bootloader AND code protection at the same time!

Ioannis

[Jumper]

It works great with a bootloader and codeprotection together. It is even possible to encrypt the hexfile into jibberish on your PC and later letting the bootloader de-jibberish it while flashing it. This way the code is safe all the way (depending on what encryption used) and if you use a PIC that is safer (i.e 18 series).

With codeprotection you can not read or write with an external programmer but the software inside the PIC (loader) can always erase and write in the codespace.

This can be done PIC to PIC or I2C or serial or what ever kind of way....

/me

[rjones2102]

Hi Jumper,

That was my understanding and plan. To use encrypted hex files and decrypt them at PC.

Do you have any recommendation of the best bootloader or any good information on how to code to talk to them?

Cheers

Rich

[milestag]

Microcode Studio's Bootloader offers a distribution license for about $400 USD and it includes the DLL library if you want to write your own interface and still use their bootloader core. I haven't purchased this yet but been very tempted. I think you could write an app to encrypt/decrypt the hex file then send it to the PIC using the DLLs. Of course the serial data to the PIC is still vulnerable to capture. Also you could distribute a simplified app with the update file already embedded.

I've been forever watching and searching for a secure bootloader. Unfortunately there seems to be no such beast on the market at present. Curious that no one offers this. My own programming skills/knowledge aren't quite up to tackling that yet, but I would certainly be willing to pay a few hundred dollars for a good reliable encrypted bootloader.

[rjones2102]

I found a bootloader the other day that professed to secure the code. It set a code protect flag in Pic. I have just been googling for it and it has gone. Or rather my memory of the search terms used is gone. How annoying.

I guess it comes down to the Pic. Is it possible to stop people reading the code back out. If the Pic doesn't have the capability, then it isn't going to happen. I will keep looking and will post if I find it.

Rich