TEST SYSTEM FOR PAYLOAD-OBC INTERFACE IN PISAT

TEST SYSTEM FOR PAYLOAD-OBC INTERFACE IN PISAT

Mr. Dhananjay V KumarMr. Adarsh R

PES Institute Of Technology, Bangalore CRUCIBLE OF RESEARCH AND INNOVATION LAB

Mr. Dayanand B MMr. Mahendra M NayakDr. V K Agrawal

AN OVERVIEW OF PISAT

• PISAT- Pesit Imaging Satellite

• Low cost nano-satellite.

• Designed and developed at the Crucible of Research and Innovation Lab, PES Institute of Technology.

• Polar Sun-synchronous Low Earth Orbit (LEO).

• One payload- GOMSPACE Nanocam C1U.

NEED FOR A TEST SYSTEM

• Independent testing of the On Board Computer(OBC) and Payload

The test system simulates all the functions of the OBC and the Payload. Hence both OBC and Payload can be individually tested by using the simulators

• Allows Bench and Environmental testing

This can be used for the bench and environmental testing of the satellite before integrating the actual payload onto it.

• Nanocam runs on free RTOS and supports FTP for data transfer.

• OBC runs on custom Real Time Executive (RTE) developed by Students at PESIT.

• Providing support for FTP on OBC is non trivial.

• GOM Space provided a new firmware on Nanocamthat allows access to memory on Nanocam using CSP protocol.

INTERFACE BETWEEN PAYLOAD AND OBC

OBJECTIVE :

I2C Interface

Serial Interface

Serial Interface

Arduino UNO

simulating Payload

Arduino UNO

simulating OBC

OBJECTIVE :

I2C Interface

Serial Interface

Payload

Arduino UNO

simulating OBC

Testing of Payload

OBJECTIVE :

I2C Interface

Serial Interface

Arduino UNO

simulating Payload

Testing of OBC

FLOW OF COMMANDS

Cam_Snap Cam_Store Cam_List Cam_Peek

Snap an Image

Store the picture

Get Details about the Image

Get Image Data

FRONT-ENDAPPLICATION

• Developed using Microsoft Visual Basic 2010 Express Edition.

• The Application runs on the system used for communicating with the Arduino.

• Allows initiating testing and also viewing test results.

COMMANDS • CSP_Snap : {0x0A,0x62,0x00,0x00}

To take a picture. A successful snap reply will output to the first 50 bytes of the received buffer.

I2C Interface

Serial Interface

Arduino UNO

simulating Payload

Testing of OBC

Command Sent

I2C Interface

Serial Interface

Arduino UNO

simulating Payload

Testing of OBC Command

Recognized

ACKNOWLEDGING SNAP

COMMANDS

• CSP_Store : {0x0A,0x62,0xC0,0x00,0x00,0x02,0x01,'p','1','.','j','p','g‘}

To store the just snapped picture to the internal memory the ‘cam store <filename>’ command.

ACKNOWLEDGING STORE

I2C Interface

Serial Interface

Arduino UNO

simulating Payload

Testing of OBC

Size of image

I2C Interface

Serial Interface

Arduino UNO

simulating Payload

Testing of OBC

119 bytes ofData Stored

COMMANDS • CSP_List : {0x0A,0x61,0xC0,0x00}

Returns data about the picture file requested for, which includes size of the file, format, base address (location on memory).

I2C Interface

Serial Interface

Arduino UNO

simulating Payload

Testing of OBC

Reply to List

• CSP_Peek : {0x0A,0x60,0x00,0x00,0x04,0x11,0x8F,0xA3,0xA0,0x78}

Returns 119 bytes from the base address mentioned

COMMANDS

I2C Interface

Serial Interface

Arduino UNO

simulating Payload

Testing of OBC

119 bytes of data

I2C Interface

Serial Interface

Arduino UNO

simulating Payload

Testing of OBC

Request next Pack of data

I2C Interface

Serial Interface

Arduino UNO

simulating Payload

Testing of OBC

119 bytes ofData Stored

I2C Interface

Serial Interface

Payload

Arduino UNO

simulating OBC

Testing of Payload

Command to initiate test

I2C Interface

Serial Interface

Payload

Arduino UNO

simulating OBC

Testing of Payload

Response to Commands from OBC

I2C Interface

Serial Interface

Payload

Arduino UNO

simulating OBC

Testing of Payload

Image data sent for viewing

Verification

Future Work

• Baud rate of the serial communication between Arduinoand computer limits the speed of I2C communication while testing.

• Insufficient memory on the Arduino board restricts the entire image data being stored in the board.

Both these problems may be solved if the Arduinosimulating the Payload is integrated with an SD card.

Conclusion

• The test system that was designed and developed was verified thoroughly for its functionalities.

• The system allowed independent testing of OBC and Payload.

• The system will be used for bench and environmental testing before the integration of the satellite into the launch vehicle.

SUMMARY• The system simulated the responses of the Nanocam to the

following commands:Snap - To snap a picture

Store - To store the image in a specific format.

List - To return information regarding image.

Peek - To return requested number of bytes of image data.

• The system verified the responses from the Nanocam and displayed the received image.

GALLERY

GALLERY