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-- STM32 Bootloader by CANBus
--
-- Johannes Hübner <[email protected]>
-- EV_BUILDER transformed to CAN BOOTLOADER;
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This boot loader does not interact with the built-in STM32 boot loader. It 
uses an interface of your choice, in this version its CANBUS CAN1. The 
interface flexibility and the independence from the BOOT pins are the 
main reasons for implementing this boot loader.

New update protocol
- 500KBaud Canbus on CAN1


1 Send '2' indicating version 2 bootloader, wait about 500ms for magic byte 0xAA
2 If no reply goto 7
3 Send an 'S' indicating that it is awaiting an update size in pages
4 If no reply within about 500ms go to step 7
4.1 otherwise send a 'P' indicating that it is awaiting the actual page 
first 8 bytes, this goes on (bit banging) until complete page is received.
4.2 When page not received within about 1s, print 'T' and keep waiting
5 When page received send a 'C' indicating that it is awaiting the pages 
checksum
6 When checksum is correct and more pages need to be received, go to 
step 4.1
6.1 if all pages have been received go to step 5
6.2 When checksum isn't correct print an 'E' then go to step 4.1
7 When done print a 'D' and start main firmware

Notes:
- By checksum I mean the one calculated by the STMs integrated CRC32 unit.
- The actual firmware has a reset command the cycle through the bootloader
- The main firmware must be linked to start at address 0x08002000
- The bootloader starts at address 0x08000000 and can be 8k in size 
(right now its around 7k)

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-- STM32 CAN Bootloader Updater
--
-- EV_BUILDER OPENINVERTER.ORG
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To send over the Hex file an C# program is included as executable.
It uses an PEAK Systems CAN to USB adapter (one of their series should do it).

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-- Compiling
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You will need the arm-none-eabi toolchain: https://developer.arm.com/open-source/gnu-toolchain/gnu-rm/downloads
The only external depedency is libopencm3 which I forked. You can download and build this dependency by typing

make get-deps

Now you can compile stm32-loader and stm32-bootupdater by typing

make
cd bootupdater
make

And upload it to your board using a JTAG/SWD adapter.

NOTE: I used part of libaries which i changed/updated/bug fixed. Becarefull before upgradeing/replacing them.