Open

Meeting Recording

Purpose

This meeting is to go over how LOS Telem and Comms will receive data and expose the data to ZP software.

Requirements (Initial)

• Data type agnostic (shouldn’t have to know the type/format of the data)

  • This is so it can be used for any type of air to air and air to ground data

• Acts as a data passthrough, no processing shall occur

• The length of the message frame would be passed in to telem and comms

Ideas

Chris:

• ZP software creates a circular/ring buffer and passes it to LOS

• Upon receiving data, it will load into the circular buffer, overwriting the oldest data if necessary

• To signal to ZP that data is ready, and to keep track of queued messages, have a count shared between ZP and LOS that LOS would increment and ZP would decrement

• Could use a semaphore to signal that there is populated data (no blocking if ZP wants to do other things)

• Problems:

Anni:

• LOS owns storage method some sort of queue/circular buffer

• ZP requests for data,

Solution to receiving data:

• Receive one byte at a time

  • Pros:

    • Does not require implementation specific detail

    • Simple

  • Cons:

    • High interrupt overhead (firing for every byte)

• Have senders send same message frame length at all times, even if true data being sent is less

  • Pros:

    • Does not require implementation specific detail

    • Simple for receiving

  • Cons:

    • Senders have to pack their data in the same format

    • Wasted time and space

• Have LOS know the message format to read in the header and appropriately read in the rest of the data

  • Pros:

    • Different sized data can be sent

    • Less interrupt overhead than One Byte method

  • Cons:

    • LOS side processing

    • Implementation specific

    • More interrupt overhead than Same Message Frame Length method (two instead of one)

Implementation

• Use a regular array/buffer (of equal to or more than the max size of message frame) to provide HAL call a place to put data.

  • In the interrupt we copy over to the circularqueue/circular buffer/ring buffer LOCALLY

• 2 “Parallel buffers” owned by LOS for sending to ZP

  • When ZP requests LOS to read from buffer 1, indicates that buffer 1 is busy

  • If buffer 1 is busy received data will be put into buffer 2

  • ???

Final Decision