Thank you, NXP!

We’re proud to welcome NXP as a new sponsor!

The brains of a solar car are essential. For our designs, we use a distributed network of a handful of microcontrollers. Each node in our network controls something different, such as managing the batteries, controlling the motor, or taking all the input from the driver. An important decision is choosing these brains, and we have reached out to NXP for their help. Last December, a few members of CalSol went down to NXP to show off Impulse and talk about our plans for the future. We received a very friendly welcome, and we are hopeful of a bright future with them.

Our own prototype and the LPCXpresso
Our own prototype connected to the LPCLink portion of the LPCXpresso

One of NXP’s interesting products is their LPCXpresso boards. These development boards include both a microcontroller for rapid prototyping and a built-in JTAG debugger, the LPC-Link. This debugger gives us significantly more power than we have had previously, allowing us to step through our running code and see the complete state of the microcontroller!

NXP has given us 40 LPCXpresso boards and has agreed to provide microcontrollers and other integrated circuits as needed. The development boards have allowed us to quickly get up to speed, and we are already making our own prototype boards using NXP’s MCU’s. You can see one of our first boards with an NXP chip (made by team member Devan Lai) in the picture to the right. We are planning on using NXP’s Cortex-M0 LPC11C14 for many systems in the car. These microcontrollers only take a few milliamps to run, an incredibly low amount for how much power they have! This, combined with their integrated support for the CAN communication protocol, makes them well suited for our applications. As well, the move to a modern 32-bit ARM architecture allows our code to be both smaller and more efficient.

All of these improvements are incremental steps towards making our best solar car yet. We’re hard at work doing everything we can to increase performance, decrease power consumption, and maximize efficiency.

Maker Faire

Maker Faire 2012
Hello everybody!

For the second year in a row, we’re at Maker Faire. This weekend event is always fun, and we meet tons of neat people with cool stories. It’s already the second day of Maker Faire, and it has been a blast. Whether it’s reconnecting with members of solar car teams from a decade ago, learning about cool technology from professionals, or telling smiling kids about the races we’ve done and are going to do, it’s a pleasure for all of our members to be here. Maker Faire is personally one of the most enjoyable outreach events for me because I get to talk to people that are genuinely interested in the technology and optimistic about the future. Plus, being around all of the other creations and seeing the sheer creativity of others is always a privilege. We hope to do this next year and keep up the annual tradition!

New Electrical Equipment from KIT Digital

Loading the truck with Chris

On Monday, we got a very generous donation from KIT Digital. After KIT Digital’s purchase of Sezmi, the company went through some internal changes and ended up with a fairly sizable collection of unneeded electrical equipment. They got in contact with us, and arranged to donate all of this equipment to CalSol.

This donation will be invaluable in augmenting our existing setup and aging equipment, and I’m excited to go through it all and inventory everything. I’ve only had time to briefly look over the contents, but from what I’ve seen I can say that we will be able to put everything to good use.

Some of the equipment we picked up from Kit Digital

All of this was made possible because of Chris Hagler, an employee of KIT Digital and a friend of our very own team member Jessica Chang. Chris thought of us when he came across the electrical equipment, and arranged everything on KIT Digital’s side to make this donation possible.

KIT Digital is now our newest Gold Sponsor! It’s because of companies like you that CalSol can thrive.

Linear Technology in a Time of Need

Last week, we were working on improving our Battery Monitoring System, and ran into a few problems. High voltage went a few places that it wasn’t supposed to, and we were left with several boards in less-than-perfect working condition. The damaged boards were manufactured by Linear Technology, and were used to individually monitor each battery cell module in our battery box. Each board would read the voltage of a dozen modules and constantly balance them to prevent overcharging or undercharging any cells. Our car has 35 battery modules, each of them at a nominal 3.6V. After working on the problems for several days, we came to the conclusion that we really needed new boards. The problems were severe enough that we had neither the time nor the materials in-house to repair our damaged boards.

At this point it was Wednesday night, and we really wanted to get Impulse running by Friday. We were swiftly running out of time. In desperation, I reached out to my contact at Linear Technology to see if he could secure new boards for us at such short notice. He called me up Thursday morning telling me that he had the boards, and I could come and get them. I drove down from Berkeley to Linear’s headquarters, picked up the replacement boards, drove back to Berkeley, and installed the brand new boards in our car. A few short hours later, we were once again able to monitor and balance all of our battery cells. Thanks to the great people at Linear, our battery system is operational and working better than ever before.

CAN Communication

Our Test Setup for Saturday

This Saturday, for the first time, we tried connecting all of our low voltage boards together. We didn’t have a high voltage power source, so we powered everything off of 12V wall sockets. Our new battery packs should be ready soon. We successfully established CAN (Controller Area Network) communication between several of the boards.

Linear Technology

We are proud to announce Linear Technology as a Gold Sponsor of CalSol.

Linear Technology are the designers and makers of the boards we are using to monitor our Li-Ion batteries. These boards are essential to both ensuring the safety of the driver and giving us real-time detailed feedback on the state of our batteries. Linear Technology has generously donated these boards, as well as offered advice on how to best use them.



Laser cutters are awesome! I got the chance to use one this weekend in making our box for the PCBs. It’s all made out of clear acrylic, so it’s kind of hard to see, but it looks really neat in person. All the holes for the ventilation and mounting are cut, and there’s some cool decals etched into the sides. We’re excited for finishing up our designs and getting them sent to Advanced Circuits for fabrication. Once we get those all done, this little beauty will be able to hold them all.


CAN Communication

BRAINs and Skeletons

Last Sunday, we had a very successful CAN (Controller Area Network) trial.  We were able to simultaneously transmit and receive CAN message packets between three of our BRAINS and the Tritium motor controller.  We tried two setups. one where the Tritium sent messages and all three BRAINS flashed lights to indicate receiving the message, and one where one BRAIN communicated with the Tritium while the other two talked between themselves on the same network.  Both tests were successful.