• Final Hardware Testing

    Thursday, April 3, 2014

    4/3/2014— Jon McKay

    Tessel version nine arrived at our office yesterday. It came in yesterday straight out of Worthington Assembly’s ovens.

    Each new hardware revision means a whole slew of tests to make sure we fixed any known problems and haven’t created any new ones.

    Eric is testing out how robust the board is after merciless shortings on both USB input and external power lines. He had designed new power circuitry to try and prevent the board from being fried in the event of a short and preliminary results are looking promising.

    I have a test rig to put our power switching circuitry through the hoops. Tessel can be powered off of USB or external power (up to 15V). We want users to be able to program Tessel over USB, then detatch out the USB cable and have their program continue running off of external power (if it’s connected) without a hiccup.

    Yes, the header on the old relay modules were assembled backwards and yes we are embarrassed. This relay module is plugged in upside down, and if you do that with the production models they won’t work.

    My test rig (above) has both USB and an external LiPo battery connected to Tessel at the same time. The USB power is intercepted by a debugging circuit board (below) that allows us to splice off USB power into a relay connected to Tessel.

    That allows Tessel to tell the relay to either connect the USB circuit or disconnect it. That is, Tessel is testing its own power regulation circuitry by switching its input power between USB and the LiPo. If the switch fails, Tessel will stop blinking lights because the program is stored in RAM and will be erased on power failure. Tessel testing itself is a beautiful thing.

    It both terrifies me and excites me that this revision of the board seems to be working to spec (knock on wood). If all goes well, we can be set to start up production early next week.

    Jon McKay

    #Update #Jon McKay #Electrical Engineering #Tessel #Technical Machine #Revision #Hardware #Testing #Test #Power #USB

July 2017

February 2017

November 2016

October 2016

September 2016

August 2016

July 2016

June 2016

April 2016

March 2016

February 2016

November 2015

September 2015

August 2015

July 2015

June 2015

May 2015

March 2015

February 2015

January 2015

December 2014

November 2014

October 2014

September 2014

August 2014

July 2014

June 2014

May 2014

April 2014

March 2014

February 2014

January 2014

December 2013

November 2013

October 2013

September 2013

August 2013

July 2013