Skip to content

Latest commit

 

History

History
160 lines (100 loc) · 4.41 KB

sdd.md

File metadata and controls

160 lines (100 loc) · 4.41 KB
Raw
<title>Svc::FileDownlink</title>

Svc::FileDownlink

1 Introduction

FileDownlink is an active ISF component. It manages downlink of files from the spacecraft.

2 Requirements

Requirement Description Rationale Verification Method
FD-001 Upon command, FileDownlink shall read a file from non-volatile storage, partition the file into packets, and send out the packets. This requirement provides the capability to downlink files from the spacecraft. Test

3 Design

3.1 Assumptions

The design of FileDownlink assumes the following:

  1. File downlink occurs by dividing files into packets of type Fw::FilePacket.

  2. One file downlink happens at a time.

3.2 Block Description Diagram (BDD)

FileDownlink BDD

3.3 Ports

3.3.1 Role Ports

Name Type Role
timeCaller Fw::Time TimeGet
cmdIn Fw::Cmd Cmd
cmdRegOut Fw::CmdReg CmdReg
cmdResponseOut Fw::CmdResponse CmdResponse
tlmOut Fw::Tlm Telemetry
eventOut Fw::LogEvent LogEvent

3.3.2 Component-Specific Ports

Name Type Kind Purpose
bufferGet Fw::BufferGet output (caller) Requests buffers for sending file packets.
bufferSendOut Fw::BufferSend output Sends buffers containing file packets.

3.4 Constants

FileDownlink has the following constants, initialized at component instantiation time:

  • downlinkPacketSize: The size of the packets to use on downlink.

3.5 State

FileDownlink maintains a mode equal to one of the following values:

  • IDLE (0): FileDownlink is idle.

  • DOWNLINK (1): FileDownlink is performing a file downlink.

  • CANCEL (2): FileDownlink is canceling a file downlink.

The initial value is IDLE.

3.6 Commands

FileDownlink recognizes the commands described in the following sections.

3.6.1 SendFile

SendFile is an asynchronous command. It has two arguments:

  1. sourceFileName: The name of the on-board file to send.

  2. destFileName: The name of the destination file on the ground.

When File Downlink receives this command, it carries out the following steps:

  1. If mode = CANCEL, then

    a. Issue a DownlinkCanceled event.

    b. set mode = IDLE and return.

  2. Set mode = DOWNLINK.

  3. Open the file sourceFileName for reading with file descriptor d. If there is any problem opening the file, then issue a FileOpenError warning and abort the command execution.

  4. Invoke bufferGetCaller to request a buffer whose size is the size of a START packet. Fill the buffer and send it out on bufferSendOut.

  5. Set a remainder r to the size of the file with descriptor d.

  6. While r > 0 and mode = DOWNLINK do:

    a. Let n be the smaller of downlinkPacketSize and r.

    b. Invoke bufferGetCaller to request a buffer B whose size is the size of a DATA packet with a data payload of n bytes.

    c. Read the next n bytes out of the file with descriptor d. If there is any problem reading the file, then issue a FileReadError warning, close the file, and abort the command execution.

    d. Fill B with (i) the data read the previous step and (ii) the appropriate metadata. Send B out on bufferSendOut.

    e. Reduce r by n.

  7. Close the file with descriptor d.

  8. If mode = CANCEL, then

    a. Invoke bufferGetCaller to request a buffer whose size is the size of a CANCEL packet. Fill the packet and send it out on bufferSendOut.

    b. Issue a DownlinkCanceled event.

  9. Otherwise invoke bufferGetCaller to request a buffer whose size is the size of an END packet. Fill the buffer and send it out on bufferSendOut.

  10. Set mode = IDLE.

3.6.2 Cancel

Cancel is a synchronous command. If mode = DOWNLINK, it sets mode to CANCEL. Otherwise it does nothing.

4 Dictionary

Dictionaries: HTML MD

5 Checklists

Document Link
Design Link
Code Link
Unit Test Link

6 Unit Testing

TODO