|1.1||28-May-2012||Add CSBF doc|
|CSBF||Columbia Scientific Balloon Facility|
|GSE||Ground Support Equipment|
|HASP||High Altitude Student Platform|
|LDBR||Long Duration Balloon Receiver|
|LOS||Line of Sight|
|ST5000||Star Tracker 5000|
|TDRSS||Tracking and Data Relay Satellite System|
For the ST5000's flight on the High Altitude Student Payload (HASP), we had to accomodate two new command formats. One format covers the commands from the ST5000 GSE (laptop) to the CSBF Ground Station and its response to the ST5000 GSE. The other covers the same commands as they emerge from the on-balloon flight receiver and are received by the ST5000 in flight. The CSBF spec is here. We elaborate on it in this document.
The CSBF GSE allows for two types of commanding: commands that are 20 bytes or fewer are broken up, 2 bytes at a time, into 8-byte packets for uplink. With the Extended Command format, for commands longer than 20 bytes, the command is passed through essentially unchanged from the ST5000 GSE to the ST5000. We chose to always use the extended format by padding out commands with spaces to at least 32 bytes. We describe the extended format.
|1||0x00||Link routing, see Table below|
|3||N||Command length, N bytes|
|4...||...||N command bytes|
|Link Selection (byte 1)||Routing Address (byte 2)|
|0 (LOS)||0x09 (COMM1) or 0x0c (COMM2)|
In response to a CSBF GSE command from the ST5000 GSE to the CSBF GSE, the CSBF GSE will reply with a 3-byte reply. Byte 2 has five possible values.
|2||0x0a||Operator disabled science from sending commands|
|2||0x0b||Routing address does not match the selected link|
|2||0x0c||The link selected is not enabled|
|2||0x0d||All other cases|
When the command emerges from the on-board Long Duration Balloon Receiver (LDBR), it has a different format, with an 8-byte header.
|2||0x37||Balloon 3, Extended cmd routing 7. The balloon number can vary.
You may see other balloons' commands mixed in with your commands.
Make sure you find out your balloon number, and check for that in each command you process.
If more than one experiment on a single balloon is using the extended command format,
the experimenters must collaborate among themselves to hash out an addressing scheme.
The CSBF command header does not carry experiment ID data.
|3||~(byte 2)||1's complement of byte 2|
|4||0x0a or 0x0c||CPU ID
I check for either one,
then save whatever the byte was for the next 1's complement test.
|5||~(byte 4)||1's complement of byte 4|
|6||N||Command length, N bytes|
|7||~(byte 6)||1's complement of byte 6|
|8...||...||N command bytes|
|8+N||TBD||Checksum: add N command bytes, mask off bottom byte.
Checksum does not include the 8 header bytes,
only the N-byte user command.