Enhanced bootloader

[iw2nzm]

Hi!

I'm using the Tiny Bootloader (for 16F) and the CCS one (for 18F over RS485) and I'm happy. However, I need more. I'm looking for a bootloader with this features:

1) it should program the CPU after a command sent over RS232/485 during normal run. This to avoid the delay at reset waiting for the command.

2) if the upgrade fails (for example due to a transmission error) it must request a retransmission of corrupted data. In other words it must never fail.

Now the questions:

1) is there any free or pay bootloader (for both 16F and 18F) with these features?

2) If you answered no at previous question I ask you: could I improve the CCS bootloader or there are issues to add these features?

3) When the bootloader is programming the flash, what about the I/O lines? I'd like they don't change.

Thank you!
Marco / iw2nzm

[Ttelmah]

1), Means this isn't a 'bootloader'...

2), Means that you simply need to add error detection to your code reading the incoming data.

What you need to do, is to have the communication code, and parser, which can detect the incoming serial, and identify the 'program' command, contained in a segment of the chip, which is programmed as 'protected'. This then writes the rest (in a manner like a bootloader), but hands the other serial commands 'on' the the main program. I the event of a programming failure, the program in the PC sending the data, will need to be told to re-send. The system will 'fail', if the data is incomplete, but still be able to be programmed gain (as with a protected bootloader).

Best Wishes

[iw2nzm]

[Christophe]

remember that using interrupts in your bootloader is hard.. even as writing your own botloader.. just don't invent the weel..

[iw2nzm]

[KaraMuraT]

You can do this that way:

If you're using a PIC which has EEPROM, and your main application is running, parse your incoming data and if you get an valid bootload command, write a certain EEPROM byte a valid character like "0x23" at address 0xFF, and than use goto_address(BOOTLOADER Reset). Don't use reset_cpu because it will simply jump to your normal application start.

Than your bootloader can check this byte whether a bootloading requested or not. If 0xFF address of EEPROM is 0x23 than starts receive process. Than passes control to application. The application starts and before while(1) loop it sets this eeprom area to a different value like 0x00 or 0xFF.

If somehow a hardware reset or startup occures yoru bootloader will heck this byte and pass the control directly to application in a blink time. No one will get hurt

But there is a problem... about power consumption. If you use this kind of approach and cannot download a valid application code after restart, your PIC will hold awake, and will consume power continuously.

That's the point where the bootloader interrupts enters the scene...
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[iw2nzm]

[quote="KaraMuraT"]You can do this that way:

If you're using a PIC which has EEPROM, and your main application is running, parse your incoming data and if you get an valid bootload command, write a certain EEPROM byte a valid character like "0x23" at address 0xFF, and than use goto_address(BOOTLOADER Reset). Don't use reset_cpu because it will simply jump to your normal application start.

Than your bootloader can check this byte whether a bootloading requested or not. If 0xFF address of EEPROM is 0x23 than starts receive process. Than passes control to application. The application starts and before while(1) loop it sets this eeprom area to a different value like 0x00 or 0xFF. [\quote]

Why?

When I parse the incoming data and, get a valid loader command and call the loader function (without reset_cpu() ) I don't need a further condition to start writing process. Simply I need to hard code the loader function into a well defined area of the flash. Another user did the same ("Bootloader and PCW compiler: memory mapping") but I can't understand where and how write ORG directives.

[quote]
If somehow a hardware reset or startup occures yoru bootloader will heck this byte and pass the control directly to application in a blink time. No one will get hurt [\quote]

Ah, maybe I misunderstood your previous tip: writing in the EEPROM a byte when a new code is going to download guarantees the system doesn't hang also in the case of errors during programming, isn't it?

[KaraMuraT]

Yes... Thats for it. And for making it rock solid do this:

Activate Watch Dog Timer for enough time like 1 s intervals. and reset the WDT for every buffer process. This helps you about interrupted bootloadings about communication errors.
_________________
/// KMT
/// www.muratursavas.com