CFE18 Gen1 - CAN Switch Board

CFE18 - Can Bus Switch Board

CFE18 stands for "Can Bus Function Extension" or colloquially "Can Switch Board" - what do you need this module for?

CAN bus connections in vehicles can sometimes pose significant challenges. This is especially true in motorsport applications, where the electronics must be housed in the steering wheel and information from trimpots or push buttons must be transmitted via CAN bus.

CANchecked now offers a small add-on module that provides 17 inputs: 8 for switches (low side) and 9 for analog inputs (0-5V signal). A voltage converter for connection to a 12V vehicle electrical system is also integrated.

There are also 3 switching outputs on the board (low side max 0.5A).

The CFE18 hardware

At just 29x27mm, the board is very compact and can be installed anywhere. The pin spacing is 2.54mm, or 3.81mm for safety reasons for the power supply.

For fastening, we have created a hole that can be used as a screw connection.

CFE18 - Can Bus Termination

A solder jumper is attached to the circuit board.

If this is closed, the CAN bus termination with 120 ohms is activated. By default, the solder jumper is OPEN.

Motorsport steering wheel

One possible application would be a motorsport steering wheel. The image shows the approximate size, with the steering wheel hub measuring 50mm in diameter. With just four connections via a coiled cable, a variety of inputs can be transmitted via CAN bus.

Connection options

Switches and trimpots can be connected to the CFE18.

But sensors such as oil pressure, fuel pressure, boost pressure, exhaust back pressure and integration into a separate housing would also be conceivable.

Digital outputs

The CFE18 has three digital outputs. These can handle a maximum load of 500mA and are connected to ground (LOW SIDE).

For this purpose, a CAN bus frame is sent every 100ms (CAN Id is configurable here - if there is a pause of 500ms between the frames, the timeout is activated and the outputs are deactivated):
(0=inactive, 1=active)

AIN smoothing

If the analog inputs fluctuate too much, they can be smoothed using software. This can be configured separately for each analog input.

The analog inputs are evaluated with each transmission (default: 20 Hz).
For example, if a smoothing factor of 4 is set, the average of the last 16 measurements is taken. This makes the value smoother, but also results in a slower response to fluctuations. A healthy balance must be found here.

The setting is done via Can Bus.