Add support to the Bus Pirate for larger flash chips

[therealdreg]

Hi! I want to add support for larger flash chips to the modern Bus Pirate. I’ve opened this issue to coordinate with you on the best way to do it

#459

https://github.com/avrdudes/avrdude/blob/main/src/buspirate.c#L989

btw, this is the modern bus pirate by @DangerousPrototypes

https://docs.buspirate.com/docs/software/avrdude/

I’ve added support by porting all the code from Bus Pirate v3 and it’s already working! But now I want it to work with AVRDude for larger flash chips—what would be the best way to do that? Let me know what you’d like me to change in the firmware and I’ll update it.

IMO: The most ideal would be for everything to work without changing the version or anything like that… that way, this firmware would automatically work with both old and new versions of AVRDude.

But maybe that’s not possible and the simplest solution is to send a new version number here, for example: CDC_SEND_STR(1, "\x02\x00\x01"); — and when that happens, you can send me new commands to read larger flash chips.

Please let me know what you want me to modify in that file so everything is as simple as possible (And compatible with older versions of AVRDude, if possible)

https://github.com/DangerousPrototypes/BusPirate5-firmware/blob/main/src/binmode/legacy4third.c#L657

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@mcuee @MCUdude Do you want me to send you a modern Bus Pirate v6 as a gift so you can test the new releases, like we did in issue #1616 ? send me an email to dreg@rootkit.es with shipping info

[therealdreg]

What about returning a 0x01 here:

this way, avrdude know that this firmware version supports large flash chips and can send me the new commands we need to handle large chips...

So, we can keep supporting older AVRDude versions too and the old Bus Pirate v3 units with old firmware will keep working just as they always did.

In the original version made by @DangerousPrototypes & cia, it works exactly the same:

https://github.com/BusPirate/Bus_Pirate/blob/cd9286dda95925b95f837a7a77e1baef2ba73006/Firmware/spi.c#L1069

So when you check the AVR version of the Bus Pirate and all that, you can send a large dummy command:

if you get an error → old firmware

if you get OK → new firmware = large chips supported

We add a new command and that’s it (AVR_COMMAND_BULK_READ/WRITE_LARGE)

[mcuee]

With regard to the FW version handling, I think @stefanrueger should be able to advise.

[mcuee]

@mcuee @MCUdude Do you want me to send you a modern Bus Pirate v6 as a gift so you can test the new releases, like we did in issue #1616 ? send me an email to dreg@rootkit.es with shipping info.

@therealdreg
Shipping info sent to the email address. Thanks a lot for your help.

[therealdreg]

With regard to the FW version handling, I think @stefanrueger should be able to advise.

awesome! @stefanrueger tell me what is the simplest way please

[MCUdude]

Thanks for your offer @therealdreg!

#459
https://github.com/avrdudes/avrdude/blob/main/src/buspirate.c#L989

I’ve added support by porting all the code from Bus Pirate v3 and it’s already working! But now I want it to work with AVRDude for larger flash chips—what would be the best way to do that? Let me know what you’d like me to change in the firmware and I’ll update it.

The older Bus Pirate implementation does not support memories with *page sizes larger than 512. But that's not an issue because there doesn't exist any AVR that has this. But as proven in #459, there is in fact an issue with larger chips.

[therealdreg]

The older Bus Pirate implementation does not support memories with *page sizes larger than 512. But that's not an issue because there doesn't exist any AVR that has this. But as proven in #459, there is in fact an issue with larger chips.

Exactly, the idea is to fix this. As you can see, the SPI C code in the firmware is super easy to understand—I can adapt whatever you need.

Sending a PAGE SIZE 0xFFFF First as a dummy-hack is just an idea to support both old and new versions of AVRDude at the same time (while allowing the legacy Bus Pirate v3 firmware to keep working as always…).

Here’s a user on the forum also reporting something similar:

https://forum.buspirate.com/t/avrdudess-flash-dump-error/1279

I just bought a test board with an ATmega128, but it’ll take a month to arrive at home....

[therealdreg]

@MCUdude @mcuee This time the product is a gift from Ian @DangerousPrototypes — he will ship it VAT prepaid, don’t worry, we always cover the VAT cost for free items. He’s covering all the expenses!