Test and Assembly Plan Results

P09141 Satellite Thermal Heater Controller

Interface Board

• The final assembly of the interface board involved creating an active low-pass offset filter using resistors, capacitors, and an op amp on a breadboard.

• Three interface boards were built, one for the master and one for each of the two slaves.

Interface Board Testing

• Using a function generator set to a sine wave at the required frequency and an oscilloscope to monitor the output, the interface board was adjusted until the output had the correct DC level, frequency, and amplitude.

• Several changes were made during testing. Capacitance values and resistance values were adjusted. An op amp was added.

Enclosure

• The enclosure was designed using Pro/ENGINEER and analyzed using ANSYS Workbench.

• Several iterations of the design were created as customer defined specifications.

• The enclosure was then machined out of 6061 Aluminum Alloy and provided to the customer for testing.

GUI

• GUI was programmed in Labview. It sends and receives over serial and displays the temperature, telemetry, and other information.

• GUI can communicate with up to 256 slaves.

GUI

• Testing was done on the GUI as we went. Each part was tested separately and then built up to a working whole.

• Loopback testing was implemented by Scott before the DSPs were ready.

Communications (PC to DSP)

• This part was programmed in C using Code Composer. Communication is done over serial and took bytes from LabView and built a message to send to slaves. Also took message from slave and communicate back to LabView via serial.

Communications (PC to DSP)

• Used Hyperterminal as a proxy LabView interface to send and receive messages. Once that was tested, the GUI was substituted for Hyperterminal.

Communications (DSP to DSP)

• The communications between the master and slave DSPs was also coded in C using Code Composer. A 40 bit message was constructed, transmitted via the PWM and low-pass filter onto the power bus. It is then demodulated using the ADC and the Goertzel algorithm and converted back into a 40 bit message. A new message is then constructed and returned.

Communications (DSP to DSP)

• The function generator was used with the ADC to test and refine the functionality of the Goertzel algorithm.

• The PWM was attached through the low pass filter to an oscilloscope and analyzed to get the right frequency and amplitde.

• The PWM and ADC were connected and a message was sent and triggered on the oscilloscope until it was correct.