Introduction

Test Description: Verify PWM generation, directional control, and CDH commanding of H-bridges on ADCS PCB.

Completed: 2026 Oct 23

Documented by: Riley Sweeney

Resources Required:

• Tools:
  
  

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

• PPE: FM testing will 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-006-6969. R-LIB-ADC-042-6976

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 H-bridges are 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.

CDH:

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, comment/uncomment test scripts in the CDH code as needed. Be sure to build before uploading.

3. Disconnect the Microsemi fusion after upload is complete.

AODCS:

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

2. Using VS code, uncomment the AODCS test scripts in the main.h file as needed. For this test it will be TEST_MAGNETORQUERS.

3. Build the project and upload by running in debug mode.

4. Disconnect the Atmel ICE when upload is complete.

Debugging/Recording signals:

• 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.
  
  

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

Test 2.4: Magnetorquers (PWM via H-Bridge) - 3x Axes

1. ADCS MCU sets all three H-bridges to the same duty cycle and polarity. To begin, check that

   1. initial duty cycle is 50% (val = 255/2)

   2. polarity is positive (PWMtorq_sw_polarity# = true).

2. Verify PWM frequency on oscilloscope. Probe the positive terminal of MT1, MT2, and MT3 areas on ADCS board. Frequency is 1000 divided by the leading edge to leading edge duration in millisec. Some oscilloscopes can measure frequency directly

   1. MT1 Freq: 61.7 Hz ~55% duty cycle

   2. MT2 Freq: 61.7 Hz ~55% duty

   3. MT3 Freq: 61.7 Hz ~55% duty
      Notes: Extra 5% likely just measuring the lag to go down from 5 V

3. Measure H-bridge output voltage magnitude.

   1. MT1 V: 4.96 V

   2. MT2 V: 4.96 V

   3. MT3 V: 4.96 V

4. Change duty cycle to 0% (Off). Measure output.

   1. MT1 V: 240-400 mV

   2. MT2 V: 240-400 mV

   3. MT3 V: 240-400 mV
      Notes: Varies with resolution. Results from 2 microseconds/point.

5. Return to 50% duty cycle, and change polarity to negative. Record PWM frequency.

   1. MT1 Freq: 61.7 Hz ~55%

   2. MT2 Freq: 61.7 Hz ~55%

   3. MT3 Freq: 61.7 Hz ~55%

6. Measure H-bridge output voltage magnitude.

   1. MT1 V: 4.96-5.04 V

   2. MT2 V: 4.96 V

   3. MT3 V: 4.96 V
      Notes: MT1 jumping between the two values.

7. Change duty cycle to 0% (Off). Measure output.

   1. MT1 V: 240-320 mV

   2. MT1 V: 240-320 mV

   3. MT1 V: 240-400 mV
      Notes: Same as step 4.

Notes:

• @ 25% duty: Measured 30%

• @ 33% duty: Measured 38%

• Falling edge adds roughly 5% to measured duty cycle