Message Interface Signals

The message interface has the following functionality:

  • The MSG_VALID strobe signal indicates when MSG has valid data or a valid header.
  • The MsgD data always starts at byte 0 of the new cycle (LSB).
  • Byte enables (MSG_BYTE_EN) are valid when the interface is outputting message data (the MSG_DATA strobe signal is asserted).
  • MSG_BYTE_EN is driven low when the interface is outputting a message header or vendor defined header.
  • When transferring data, MSG_BYTE_EN does not have any 0s in between 1s. Therefore, the data will be contiguous without any byte valid low.
  • The PCIe Controller may de-assert the MSG_VALID signal during the message transfer (in between MSG_START and MSG_END).
  • The MSG output is only valid when MSG_VALID is 1.
  • The MsgD payload size is limited by the PCIe Controller's MAX_PAYLOAD_SIZE value.
  • All header bits are in a single stripe.
Note: Refer to Message Interface for message signals description.
Figure 1. Message Interface Waveforms