Zero Race is moving across Europe at a challenging pace—see the Zero Race blog for details. We have had no time to replace our temporary suspension fix with a permanent repair, or to fix the communications problems in the battery management system. So while the rest of the race is in Brussels, we have moved ahead to Sven’s workshop in Berlin to give us a few days to fix these problems before rejoining the event when the other teams arrive on Tuesday. (Sven is the main rider of Team Vectrix, and one of our benefactors. He has also booked to drive Trev between Moscow and Shanghai, so is keen to have the car running reliably.)
Communications between the crew in Europe and the rest of the team in Adelaide is improving. In fact, last night we achieved a major breakthrough in remote automotive diagnosis:
Peter, in Adelaide, hooted the horn, in Berlin.
Here is how we did it. The horn button in Trev, along with all the other driver buttons and controls, is connected to a microcontroller under the dash. When the horn button is pressed, the microcontroller sends a ‘horn on’ message to the rest of the car via the Controller Area Network (CAN) bus—a pair of communications wires which connects all of the electrical devices in the car. Another microcontroller, the front right lighting controller, receives this message and turns on the horn. When the driver releases the horn button, the driver controls box sends a ‘horn off’ message and the front right lighting controller turns off the horn. Easy. Connections are made in software, and there are no large looms of wires running around the car.
The CAN protocols automatically handle message priorities and arbitration between devices wanting to send messages at the same time.
Any device can listen in on the communications. To diagnose problems, we connect a netbook computer to the car and log the CAN messages. But we can also put messages on the CAN bus from the netbook. Last night, Nick had the netbook connected to the car, and Peter (in Adelaide) was operating the netbook via the internet using TeamViewer software.
Hooting—via wireless modem, internet, Android phone, netbook computer and CAN bus—was inevitable.