LISSA FM Gyroscope Interface Test

Introduction

Test Description: Testing the interface between CDH and ADCS with focus on operating and configuring the gyroscope "in flight". *NOTE* This test can be performed in parallel with the FM Magnetometer Test.

Completed: 

Documented by: Riley Sweeney

Resources Required:

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

• Hardware and Equipment: UMS-0866 ADCS FM CCA, UMS-0802 CDH FM CCA, UMS-0803 Power FM CCA, power supply, Microsemi fusion, Atmel ICE, USB to TTL device, laptop to interface with both boards.

• 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-005-6964. R-LIB-ADC-032-6371. R-LIB-ADC-240-7001.

Pass Criteria: The gyroscope shall be able to change its configuration upon command from CDH (R-LIB-ADC-005-6964) (ADC-032-6371). The gyroscope shall output rotation data to CDH at a minimum of 5 Hz (R-LIB-ADC-240-7001).

Test Apparatus

This test will occur on the FM FlatSat.

1. Check the connections between PCBs on the FlatSat. The power PCB should be connected to a power supply with two wires for power and ground. This PCB should also connect to CDH using an intermodular connector.

2. The CDH PCB should have two intermodular connectors, one coming from the Power PCB, and one going to the AODCS PCB.

3. The gyroscope is located on the AODCS PCB. No other peripheral sensors or actuators need to be connected to AODCS.

Test Set-Up

With the FlatSat set up, this section focuses on setting up the necessary software for the PCBs and data collection.

1. Connect the Microsemi fusion to the debug port on the CDH CCA. Connect the other end of the Microsemi fusion to your laptop via USB.

2. Using SoftConsole, upload the CDH code from the 'gyroTest' branch in the flight software repository on Github.

3. Disconnect the Microsemi fusion.

4. Connect the Atmel ICE to the debug port on the AODCS PCB. Connect the other end to your laptop via USB.

5. Using Microchip studio, upload the AODCS code from the 'gyroTest' branch in the ADCS software on Github.

6. Disconnect the Atmel ICE.

7. Connect the USB to TTL device to the UART pins on the J1 header on CDH. Connect the device to your laptop to receive data from CDH.

Test Procedures

The gyroTest code is quite simple, it follows the steps shown below.

1. Set the output voltage on the power supply to 6.4 V, which is approximately bus voltage.

2. Turn on the power supply. The power PCB will boot into critical hold mode, you must wait for this period to end for power to be supplied to CDH and AODCS. The output current on the power supply will jump when this period ends.

3. CDH requests the  gyroscope configuration from AODCS and outputs it over UART to the laptop.

4. CDH polls the gyroscope for rotation data for 30 seconds and sends it to the laptop

5. CDH sends a new configuration to update the gyroscope. You can decide what specifically to change by updating the values of 'newConfig'.

6. CDH requests the gyroscope configuration from AODCS and outputs it to confirm the configuration update.

7. CDH polls the gyroscope for rotation data for 30 more seconds and sends it to the laptop.

Test Close-Out

1. Disconnect the USB to TTL device upon test completion.

2. Turn off the power supply.

3. The FlatSat does not need to be disassembled.

Data Analysis

The results of this test will include two gyroscope configurations and two sets of timestamped gyroscope data. This data does not have a "ground truth" to reference to assess the accuracy of the data. In addition, the PCB will be stationary on the FlatSat. Analysis is focused on the effects of different configuration changes.

1. Create plots for both sets of gyro data.

2. Compare and contrast these results. In particular, look for differences in the prevalence of noise, output data rate, and drift. Since the gyroscope nominally has rotation rates of zero in all axes during data collection, these effects should be clear.

These configurations can be transferred to the guidance system gimbal test to help improve its performance. That test will provide a better evaluation of the gyroscope's measurement accuracy.