Host Communication Protocol
2.0
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The communication stack implemented on the embedded devices by FPC follows the following specification.
The physical layer have a fixed size buffer of 256 bytes.
The link layer handles packet consistency.
Each packet received is acknowledged on the link layer, if an error occurs no retransmission is done on this level, instead the error is propagated upwards.
Channel | Size | Payload | CRC |
---|---|---|---|
2 bytes | 2 bytes | size bytes | 4 bytes |
All fields are using unsigned data types.
The transport layer handles packet segmentation.
As the PHY MTU is 256 bytes the maximum payload per segment is 242 bytes.
Errors are propagated upwards.
Size | Seq Nr | Seq Len | Payload |
---|---|---|---|
2 bytes | 2 bytes | 2 bytes | size bytes |
All fields are using unsigned data types.
The application layer is a optional security layer, the default implementation is clear text (unsecure).
If a security solution is used it will be part of that products documentation.
The HCP frame is described in the hcpf HCP frame format section.