30 lines
1.9 KiB
Plaintext
30 lines
1.9 KiB
Plaintext
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General:
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- All messages end in a two-byte CRC-16/CCIT-FALSE
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Connection Sequence:
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- For some reason, the first 4 packets are 16 bytes long.
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<- Controller starts by sending a "discover" message(0x0A) every 20ms
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- Unsure what any of the fields in this packet mean, likely that a multi-byte identifier for the controller is included somewhere, and flags
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-> When FC is powered on, it responds to the 0x0A with a 0x03
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- For 0x03 the first two bytes seem to be flags, and bytes 8-11 are the brains 4-byte ID, byte 7 also has bits set, but unsure what they mean
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<- Controller responds to 0x03 with 0x13
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- No idea what any of these fields mean, but sending the same seems to work
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-> FC responds with 0x02 ACK
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- From now on, all packets are 32 bytes long
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<- Controller sends "start something idk" packet 0x11
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- All bits are set to zero in the packets I've seen
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-> FC responds with 0x04 with byte 2 set to 0x14
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<- Controller ACKs 0x02
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-> FC ACKs the ACK 0x02
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Control Sequence:
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- After this startup sequence is completed(actually just after the first 16 byte sequence is completed, not sure what the 0x11 sequence is for), the controller starts a sequence of sending 0xA7 packets every 20ms
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<- Controller sends 0xA7 with the robot name, control status flags, system status flags, and timer.
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- At this point the FC can respond in two ways:
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1) -> FC sends 0x02 to ACK the 0xA7, controller continues operation and sends 0xA7 again in 20ms with the same info
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2) -> FC sends 0x53 to update the info with control flags and timer. Controller sends 0xA7 again in 20ms and it should contain the updated info.
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- The way I handle this in the code is to have an "expected state" for the timer and control flags(control flags can be updated over serial).
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- When receiving a 0xA7, if the info matches the "expected" send a 0x02
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- When receiving a 0xA7, if the info does not match the "expected" send a 0x53 with the expected info
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