Intro
For my solar-powered bicycle, the Maxun One, I have developed the ebike cable killer. This is a 2-wire control bus for e-bikes. Since just 3 wires are needed for the entire control of an e-bike, very robust RC-model connectors can be used:
It has several functions:
- It gets rid of the rat's nest of cables coming out of the motor controller
- It can communicate to an LCD display or smartphone wirelessly.
- It supports all kind of bicycle electronics, such as torque sensor, temperature sensor, shift servo etc..
PCB
Wire reduction
Here is a view of the rat's nest of cables coming out of a motor controller:
Here's the new reduced cabling with the ebike cable killer:
2-wire control bus
To reduce the number of wires I have developed a current controlled bus, so-called “Cucobus”. It is a bus with the least number of wires possible, only two: GND and 5V.
Maximal 7 switches can be connected to the Cucobus. When a switch is pressed, the 5V is loaded with a resistor, see the circuit. The cable killer measures the current from the 5V and deduce from this which switches have been pressed. For safety reasons, no errors are allowed here. As a result, the development of the cucobus took a lot of time and is quite complicated. For example, compensation is made for the supply current of the Hall sensors. The bus is continuously calibrated and if a suspicious fault occurs, the system is shut down.
Two current controlled busses are needed, one for the electronics at the bicycle frame and one for the handle bar. Just a single 3 pole connector is needed for the control of an ebike:
The E-bike cable killer works for all types of motor controllers and is small enough to fit into the small KU63. It consists of two PCB’s, the main PCB is built into the motor controller, the front PCB replaces the front plate thereof.
Circuit description
This is the old circuit version v0, used in the Maxun One solar bike for many years now:
Here's the newer circuit v1 that is not finished yet:
Future development
The E-bike cable killer is very robust, I've used it at my solar bike for more then 10,000km without any errors. Still, a new improved version has to be made. But since I'm working on an important invention, I don't have time to required finish this project. I would like someone else to take over this project, I will help with that.
These are the main improvements:
- The 5V switching power supply is now synchronous
- The SAMD51 is replaced by an STM32 controller
Fora
Control of additional components
The cable killer has two connectors, JM4 and JM5, for the control of extra components such as lights, torque sensor, temperature sensor, shift servo etc:
2-wire control bus development
Here are photos that give an insight into how the Cucobus works:
