Programming over USART1

[belohoub]

Allow KETCube programming over the same interface as used on the KETCube Terminal.

[belohoub]

https://www.st.com/content/ccc/resource/technical/document/application_note/b9/9b/16/3a/12/1e/40/0c/CD00167594.pdf/files/CD00167594.pdf/jcr:content/translations/en.CD00167594.pdf

[belohoub]

STM32 bootloader will be used to do so. As the information spread on the web is a bit confusing, I'll put the research results in a bit structured way below:

• our board has boot0 pin grounded; we need to jump into bootloader from firmware

• there is lot of tutorials (following STM docs) showing how to jump into bootloader area, e.g.:

  • http://www.onarm.com/forum/64128/
  • https://stm32f4-discovery.net/2017/04/tutorial-jump-system-memory-software-stm32/
  • https://community.st.com/s/question/0D50X00009sTgmrSAC/usb-dfu-bootloader-start-from-source
  • https://community.st.com/s/question/0D50X0000AAGQ7ASQX/stm32l072-jumping-to-embedded-bootloader-from-application-code
  • https://github.com/micropython/micropython/blob/0986675451edbdcbe31d90ddacf8f6dc3327a4ae/stmhal/modmachine.c#L197-L223
  • https://www.youtube.com/watch?v=cvKC-4tCRgw

• However following those tutorials doesn't work because STM's bootloader checks the boot PINs state during initialization

• It is necessary to follow these documents:

  • AN2606 - Application note for STM32 microcontroller system memory boot mode (https://www.st.com/content/ccc/resource/technical/document/application_note/b9/9b/16/3a/12/1e/40/0c/CD00167594.pdf/files/CD00167594.pdf/jcr:content/translations/en.CD00167594.pdf)
  • RM0376 - Reference manual for Ultra-low-power STM32L0x2 advanced Arm®-based 32-bit MCUs (https://www.st.com/content/ccc/resource/technical/document/reference_manual/63/3c/c0/51/1c/fb/44/d4/DM00108281.pdf/files/DM00108281.pdf/jcr:content/translations/en.DM00108281.pdf)

• In AN2606, on page 223, the stm32l082 bootloader is described

• Table 2 in AN2606 shows several patters (pattern 2 and pattern 7 groups) leading to bootloader activation:

  • Boot0(pin) = 1 and nBoot1(bit) = 1
  • Boot0(pin) = 1, nBoot1(bit) = 1 and BFB2(bit) = 0
  • Boot0(pin) = 0, BFB2(bit) = 1 and both banks don’t contain valid code
  • Boot0(pin) = 1, nBoot1(bit) = 1 and BFB2(bit) = 1

• This is also demonstrated in Figure 58 on page 225

• In our case, the only possibility is to use the 3rd pattern; the bootloader initialization procedure will be then as follows:

  • invalidate Bank1 and Bank2 first address content
  • set BFB2 to 1
  • reload

• this procedure should be initialized by a custom startBootloader command from the firmware (KETCuibe Terminal)

• Advantages:

  • built-in STM32 bootloader can be used (all supported interfaces can be used)
  • boot0 pin remains grounded in final application

• Disadvantages:

  • when startBootloader command is executed, the running application cannot be started, new firmware must be loaded or at least first pages in bank1 and bank2 must be recovered

[belohoub]

• After some coding, the FLASHER-STM32 (https://www.st.com/en/development-tools/flasher-stm32.html) bootloader demo application is able to initialize communication with KETCube without touching boot0 PIN. However:
  • FLASHER-STM32 crashes in "step 3"
  • but it crashes also when boot0 PIN is used to jump to bootloader area

It may be a bug in FLASHER-STM32 ... ?

[belohoub]

KETCube can be programmed by using the open-source tool stm32flash (https://sourceforge.net/projects/stm32flash/).

Enter following command into KETCube Terminal:

>> set core startBootloader

Use stm32flash to view KETCube details:

$ ./stm32flash /dev/ttyUSB0
stm32flash 0.5

http://stm32flash.sourceforge.net/

Interface serial_posix: 57600 8E1
Version      : 0x31
Option 1     : 0x00
Option 2     : 0x00
Device ID    : 0x0447 (STM32L07xxx/08xxx)
- RAM        : 20KiB  (8192b reserved by bootloader)
- Flash      : 192KiB (size first sector: 32x128)
- Option RAM : 32b
- System RAM : 8KiB

Use stm32flash to write KETCube firmware:

$ ./stm32flash -w KETCube.hex -e 255 -v -g 0x0 /dev/ttyUSB0
stm32flash 0.5

http://stm32flash.sourceforge.net/

Using Parser : Intel HEX
Interface serial_posix: 57600 8E1
Warning: the interface was not closed properly.
Version      : 0x31
Option 1     : 0x00
Option 2     : 0x00
Device ID    : 0x0447 (STM32L07xxx/08xxx)
- RAM        : 20KiB  (8192b reserved by bootloader)
- Flash      : 192KiB (size first sector: 32x128)
- Option RAM : 32b
- System RAM : 8KiB
Write to memory
Erasing memory
Wrote and verified address 0x08007f80 (19.61%) Done.

Starting execution at address 0x08000000... done.

[belohoub]

Just to clarify, stm32flash allows to write up to 255 pages at once (parameter -e).

I don't understand this limitation, however removing the range limitation from stm32flash allows to write KETCube memory at once:

$ ./stm32flash -w KETCube.bin -e 1535 -v /dev/ttyUSB0
stm32flash 0.5

http://stm32flash.sourceforge.net/

Using Parser : Raw BINARY
Interface serial_posix: 57600 8E1
Version      : 0x31
Option 1     : 0x00
Option 2     : 0x00
Device ID    : 0x0447 (STM32L07xxx/08xxx)
- RAM        : 20KiB  (8192b reserved by bootloader)
- Flash      : 192KiB (size first sector: 32x128)
- Option RAM : 32b
- System RAM : 8KiB
Write to memory
Erasing memory
Wrote and verified address 0x08029348 (100.00%) Done.

[belohoub]

Note: the 255 pages limitation will be removed in the next release of stm32flash (fix is a part of current dev version): https://sourceforge.net/p/stm32flash/tickets/115/

[belohoub]

The official STM32 tool "STM32CubeProgrammer" works fine

$ ./STM32_Programmer.sh -c port=/dev/ttyUSB0 -w KETCube.bin 0x8000000
      -------------------------------------------------------------------
                        STM32CubeProgrammer v2.4.0                  
      -------------------------------------------------------------------

Serial Port /dev/ttyUSB0 is successfully opened.
Port configuration: parity = even, baudrate = 115200, data-bit = 8,
                     stop-bit = 1,0, flow-control = off

Timeout error occured while waiting for acknowledgement.
Activating device: OK
Chip ID: 0x447 
BootLoader protocol version: 3.1
Device name : STM32L07x/L08x/L010
Flash size  : 192 KBytes (default)
Device type : MCU
Device CPU  : Cortex-M0+

Memory Programming ...
Opening and parsing file: KETCube.bin
  File          : KETCube.bin
  Size          : 175240 Bytes
  Address       : 0x08000000 

Erasing memory corresponding to segment 0:
Erasing internal memory sectors [0 1369]
Download in Progress:
[==================================================] 100% 

File download complete
Time elapsed during download operation: 00:01:00.096