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+# SplitflapBus protocol
+
+The SFBus is an RS485 based protocol. It has a singular master node and up to 32 client nodes per interface.  It can adress up to 65536 devices.
+
+## Packet format (1.0)
+```
++------------++----------+--------+---------+----------------+-----------+
+| Start-Byte | Protocol- | Frame- | Adress  | Payload        | Stop-Byte |
+|            | Version   | Length |         |                |           |
+| 0x2B       | 0x00      | 1 byte | 2 bytes | framelegth - 3 | 0x24      |
++------------+-----------+--------+---------+----------------+-----------+
+ The frame length includes the address and stop-byte
+ Therefor, the payload is framelegth - 3.
+```
+
+## Packet format (2.0)
+*This i not yet implemented!!*
+```
++------------++----------+--------+---------+----------------+-----------+
+| Start-Byte | Protocol- | Frame- | Adress  | Payload        | Checksum  |
+|            | Version   | Length |         |                |           |
+| 0x2B       | 0x00      | 1 byte | 2 bytes | framelegth - 4 | 2 bytes   |
++------------+-----------+--------+---------+----------------+-----------+
+ The frame length includes the address and stop-byte
+ Therefor, the payload is framelegth - 4.
+```
+
+## Payload format (Protocol Version 1.0 + 2.0)
+The first byte of the payload is the command. This tells the controller
+what to do or what data to expect next.
+
+```
++----------+----------------+
+| Command  | Payload        |
+| Byte     |                |
+| 1 Byte   | framelegth - 4 |
++----------+----------------+
+```
+
+
+### Ping
+Check if a module is present under this device id
+- Payload: `0xFE`
+- Expected response: `0xFF`
+
+### Reset
+Resets the device controller. Should be done after address or calibration change.
+
+Can also be done to clear error flags
+- Paylad `0x30`
+- Expects no response.
+
+### Motor power on
+- Paylad `0x21`
+- Expects no response.
+
+### Motor power off
+- Paylad `0x20`
+- Expects no response.
+
+### Display flap
+- Paylad `0x10 <1 byte: flap id>`
+- Expects no response.
+
+### Display flap with full rotation
+- Paylad `0x11 <1 byte: flap id>`
+- Expects no response.
+
+### Read EEPROM
+- Payload `0xF0`
+- Response is `0xAA` followed by content of EEPROM (5 bytes). See mapping below.
+
+### Write EEPROM
+- Payload `0xF1 <5 bytes of eeprom content>`
+- Response is `0xAA` followed by new content of EEPROM. See mapping below.
+
+### Get controller status
+- Payload `0xF8`
+- Response is 7 bytes long.
+
+```
++--------+------------+------------+
+| Byte 0 | Byte 1 - 2 | Byte 3 - 6 |
+| 8-Bit  | 16-Bit     | 32-Bit     |
+| Status | Voltage    | Rotations  |
++--------+------------+------------+
+  |         |            |
+  |         |            +-> uint32 counter of total rotations
+  |         |
+  |         +-> uint16 raw ADC readings.
+  |             double __voltage = ((double)_voltage / 1024) * 55;
+  |
+  +->   Bit 0:  delta too big. Sensed position not equal to expected position
+        Bit 1:  no home found. Cannot sense home magnet.
+        Bit 2:  fuse blown
+        Bit 4:  device powered down. Can be changed by sending: 0x21
+        Bit 5:  failsafe active. Device failed cirtically and stopped operation.
+                can be recovered with reset: 0x30
+        Bit 6:  device busy. Device is currently moving to the next flap position
+
+```
+
+## EEPROM format
+```
++------------+------------+--------+
+| Byte 0 - 1 | Byte 2 - 5 | Byte 6 |
+| 16-Bit     | 32-Bit     | 8-Bit  |
+| Address    | Rotations  | Okay   |
++------------+------------+--------+
+  |             |           |
+  |             |           +-> do not change
+  |             |
+  |             +-> uint32 counter of total rotations
+  |
+  +-> uint16 device address
+```
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