LISSA FM Star Tracker Test

Introduction

Test Description: Test the interface and function of the flight model star tracker for LISSA.

Completed: 

Documented by: Riley Sweeney

Resources Required:

• Tools: Required tools such as cleaning equipment, chemicals, jigs, hand tools, etc.

• Hardware and Equipment: UMS-0900 FM star tracker, UMS-0802 CDH FM, 2x power supply

• PPE: FM testing will likely occur in the clean room. Please follow all clean room safety guidelines. Please wear an ESD bracelet and use ESD mat when working with electronics.

Verification Activities: R-LIB-ADC-003-6961. R-LIB-ADC-005-6962. R-LIB-ADC-006-6971.

Pass Criteria: The star tracker shall interface with CDH (R-LIB-ADC-003-6961) and send telemetry (ADC-005-6962). The star tracker shall limit its current draw (R-LIB-ADC-006-6971).

Test Apparatus

Provide a description of the test apparatus that will be used, and the process to install the test article. This is particularly important for Vibration and TVAC activities.

Test Set-Up

Provide step-by-step instructions for additional activities needed before beginning the test. This could include preparing software, data storage folders, or installing sensors.

Test Procedures

The fastest procedure to operate the star tracker is as follows:

1. Send GO 0x07 to turn on the functional processor.

2. Send a sequence of COMBINATION 0x00001E2F commands. These will keep the functional processor running at all times and not reboot between cycles. This is the simplest way to get a result from the star tracker, but is not recommended on orbit due to a risk of radiation-induced crashes.

3. Send one or more READ EDAC commands to read status data from the supervisor processor. This is device telemetry.

The procedure that is considered nominal operation in the star tracker ICD is to trigger and poll results:

1. Send INIT 0x00002000 to start Idle state

2. Send GO 0x0B to transition to Processing state, booting the functional processor from NAND flash, and enabling the timeout.

3. Poll with READ EDAC commands the “Result structure length” channel until enough bytes have arrived to encompass the desired star tracker data.

4. Send one or more READ RESULT commands to read the star tracker data.

5. Send one or more READ EDAC commands to read status data from the supervisor processor. This is device telemetry.

If polling is not desired:

1. Send INIT 0x00002000 to start Idle state

2. Send COMBINATION 0x00001E0B to transition to Processing state, booting the functional processor from NAND flash, and enabling the timeout.

3. Wait for the COMBINATION reply packet, which will contain the return code, quaternion, angular rate, and epoch time.

4. Send one or more READ EDAC commands to read status data from the supervisor processor. This is device telemetry.

Other functions to test:

WRITE KEPS to update the orbit parameters necessary for accurate quaternion results. Best practice is to update this directly from SGP4 results.

READ TIME/WRITE TIME to compare the RTC on CDH to the RTC on the star tracker. 

Test Close-Out

To finish the test:

1. Document both the reply packet and device telemetry as it appears on the CDH.

2. Document the maximum current draw