stcgal/doc/stc89-protocol.txt
Grigori Goronzy cf0d93b179 Add notes about STC12A and STC89 protocols
Nothing is implemented yet, but this should help with the
implementation when I finally get the chips from China.
2014-01-12 01:39:14 +01:00

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STC89
This is the first generation protocol of STC MCUs.
Differences to STC12:
* Uses NONE parity instead of EVEN parity.
* Checksum calculations are different: only a single-byte modular sum is used.
* Baudrate handshake isn't initiated with a type 0x50 packet; this is simply
skipped.
* After the handshake a special ping-pong sequence of 0x80 type packets needs
to be sent.
This doesn't appear to serve any purpose - possibly this is just done to
verify that the connection works reliably. STC12 doesn't require it anymore
because parity and the improved checksum ensure correct operation.
* Erase is acknowledged with type 0x80 packet instead of type 0x00
* After flash programming, there is no finish packet, type 0x69, sent; this
is simply skipped.
* Baudrate handshake
- Uses normal speed (/32) UART timing instead of double speed (/16)
- IAP delay has some differences (see datasheet)
* Erase procedure
- A different magic sequence is used
(6 bytes with value 0x33)
- No size/range is supplied
- response code has type 0x80