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HP Prime USB HID Packetizing protocol

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Oscar Spierings edited this page Feb 20, 2022 · 1 revision

The HP Prime HID protocol can be classified into three categories:

  • Version 1: Initial protocol shipped with the original Prime, still backwards compatible and default starting point on connection.
  • Version 2.0 [Build > 10517]: new protocol; adds header to first frame containing: frame number, message ID and Message length. Acks are added
  • Version 2.1 [Build > 10591]: Single sided sending, sending is only allowed for ~50ms after sync and everything needs ACK.

When the connection with the HP Prime is initiated, the protocol defaults to version 1. To switch to version 2 you need to first request the calculator info from the prime with the old protocol (0x00, 0xFA). Only after the calculator info request you'll be allowed to switch to protocol version 2.0 or 2.1.

Magic packet to switch protocol: {0xFF, 0xFE, 0x00,0x00,0x00,0x00,0x00, <0x00 for v2.0 | 0x01 for v2.1> }

visual protocol description

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