[Ben’s] added some nice goodies to his Volvo in the form of an in-dash computer. The system monitors two pressure sensors for boost and vacuum, as well as reading RPM, O2, and exhaust directly. All of this is tied into the touch interface running on an eeePC 900A. But our favorite feature is that the system requires you to enter a PIN to start the ignition. The forum post linked above is short on details so we asked [Ben] if he could tell us more. Join us after the break for a demonstration video as well as [Ben’s] rundown on the system.

[youtube=http://www.youtube.com/watch?v=_yPlFFCGi2A]

Ben writes:

Hi, great, glad you like it. The EEE 900A has a 2GB ram upgrade and a 16GB SSD upgrade, running windows 7. I modified the computer so it could fit directly behind the screen, which involved relocating the USB ports, and also using a HP webcam from a broken laptop as a back up camera.

The black box has three circuit boards. I’ll send you some pictures of the most current version later. The first board is for power, It has a 3.3v and 5v regulators to provide the two voltage rails, and the three relays. One relay controls the power supply to the netbook, the second controls the car’s actual starter, and the third controls the auxiliary power and lighting system.

The second board uses two freescale semiconductor pressure sensors, one to read boost and the other to read vacuum. It also has a secondary microcontroller (A PIC18F2550) to read a direct RPM input as well as a wideband o2 sensor in the exhaust. This uC is running in i2c slave mode.

The final board in the back is a PIC18F4550, which has direct control over the relays, the secondary controller, and also directly reads the two pressure sensors. Both controllers run software written in PICBASIC.

Now the part that I like about the interface box, is in order to talk to the computer, it uses only the PIC18F4550’s USB port. one usb connection is all that the computer talks to the car with.

The software running on the netbook is an application that provides a front end to the control box, A PIN is required to be entered, and once the PIN is correct, you are then able to start the car via the
button on the screen. The normal key method of starting no longer works. For security, The interface ONLY sends the PIN number to the control box, the control box has a PIN number saved and encrypted on the PIC’s internal eeprom. The entire application was written in VC++, .net, and provide me with accurate boost, vacuum, RPM, and AFR on screen. Touching a gauge on the screen enlarges it, and minimizes the other two gauges for enhance readability.

It’s all cleanly installed in my 1998 S70 T5, which was an automatic from the factory and that I swapped to manual in January this year. To power the entire system on, you only need to press the unlock button on the keyfob. by time you get to the car, the computer is running, and the control box is connected to my software and waiting. Locking the doors via key fob (using the key on the door also works just as well) tells the contol box to use a transistor to electrical press the EEE’s power button and put it into sleep mode. Once the EEE is off, it cuts power to the EEE, and then both controllers go into sleep mode, drawing minimal current. I’ve left the car for a couple weeks with the entire thing hooked up, got home, and started it right up and drove away. I designed the entire system like any company would, to ensure reliability. There are safety measures that only I know about, that allow me to re-enable the standard key ignition in case of an emergency.