Flasher tool

[antoinealb]

This PR implements the flashing tool for the bootloader. It is almost complete and should be testable with real hardware soon. I used the code from @nuft as a start, and added tests. Some corner cases might not be covered yet and maybe some are only observable using real hardware.

1.0 feels so close now :+1:

[antoinealb]

The last missing stuff in my opinion is waiting for boards to be ready (related: #27).

@nuft Could you this tool quickly in real life ? Simply adding a few time.sleep() to flash_binary and crc_regioncould be enough to make it work.

[msplr]

Great! Already some remarks for the read_can_datagram() function:

• it should ignore CAN frames which aren't bootloader frames.
• the 'start of datagram' bit in the id should be respected.
• it should listen only to frames addressed to the client's id.
• it should listen only to specified source(s)

However, it should already work as it is now. I'll try to test it today. I'll review more thoroughly later.

[antoinealb]

Well since we only have 3 month left before the Belgian contest. If it works well enough, ship it. We will fix it when / if problems arise.

[msplr]

So I came to run it with a prototype bootloader, and it worked! I had to make some little changes:

• I instantly had an error here. The data from tuple returned by decode_datagram() isn't unpacked. This wasn't detected by the tests and when I fixed it in the code, the tests break.
• You forgot to send a 'run application' command.
• As you mentioned: I needed to add some time delay after flash writes. We need to fix this by polling the status.
• There was an error in 'read_can_datagram()' when the serial read times out (probably some missing check):

[...]
Verifying firmware...
Traceback (most recent call last):
  File "bootloader_flash.py", line 169, in <module>
    main()
  File "bootloader_flash.py", line 154, in main
    valid_nodes_set = set(check_binary(serial_port, binary, args.base_address, args.ids))
  File "bootloader_flash.py", line 88, in check_binary
    crc = crc_region(fdesc, base_address, len(binary), node)
  File "bootloader_flash.py", line 128, in crc_region
    answer = read_can_datagram(fdesc)
  File "bootloader_flash.py", line 116, in read_can_datagram
    frame = can_bridge.decode_frame(frame)
  File "[...]/can-bootloader/client/can_bridge.py", line 36, in decode_frame
    unpacker.feed(data)
  File "_unpacker.pyx", line 276, in msgpack._unpacker.Unpacker.feed (msgpack/_unpacker.cpp:276)
TypeError: 'NoneType' does not support the buffer interface

[antoinealb]

I have fixed the two errors. I will add the application run command. For the delays, I don't know: is it much of a problem ? We can still add it later.

[msplr]

I'm ok with merging now, since it is mostly working. However, before 1.0 I want these issues fixed:

• fix timing by polling the targets.
• proper CAN datagram handling to allow addressing of multiple targets.

[antoinealb]

Where did you add the delays ? Also I am not sure what you mean by proper CAN datagram handling.

[antoinealb]

So once #43 is merged, I will be able to fix timing properly.

[msplr]

For testing, I just added a delay of about 0.3 seconds to write_command(). With the CAN datagram handling I meant mostly the issues mentioned in my first reply. Most important of this: distinguish between different source IDs to allow multicast polling, as proposed by @Stapelzeiger in #27.

[antoinealb]

Well I am not sure if multicast polling is critical. I would say we already finished the critical part of the project, don't you think so ?

[msplr]

Yes, It doesn't need to be implemented right now. Though it doesn't harm if we lay things out now for later improvement. For me, we can merge.