LISSA FM Sun Sensor Interface Test

Introduction

Test Description: Testing the interface between CDH and sun sensors through the AODCS PCB.

Completed: 

Documented by: Riley Sweeney

Resources Required:

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

• Hardware and Equipment: 2x UMS-0381 FM, 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-005-6966. R-LIB-ADC-034-7002.

Pass Criteria: The sun sensor shall send sun vector data to CDH at a minimum rate of once per 10 seconds.

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. Sun sensors connect to the AODCS PCB using a ten pin connector. There are two ports on the PCB, SUN_SENSOR_1 and SUN_SENSOR_2. Both ports should be tested at the same time using two flight model sun sensors.

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 'sunSensTest' 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 'magTest' 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 sunSensTest 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 a measurement from Sun Sensor 1.

4. CDH decomposes the angle from the raw data.

5. CDH sends the result to the laptop over UART.

6. CDH repeats steps 3-5 for sun sensor 2, 3, and 4. (Each sensor has two optical arrays to read) 

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

Data analysis for this test is minimal.

1. Verify that the angles given agree marginally with the direction of the light source.

2. Verify that each sun sensor (two sensor readings) output at a rate of at least once per 10 seconds.

This will verify the interface between CDH and the sun sensors. For accuracy and calibration testing, see the FM Sun Sensor Performance Test.