Did you know that Retrofit can be cheaper than Repair ?
This cross trainer escaped the bin and became connected !
Repair or Retrofit ?
This cross trainer had an electronical issue. Unfortunately, no broken component was visible and a complete reverse engineering would have been needed to repair the electronic system. But this is far too costly. The supplier was not able to give any usefull information. So, what can we do ?
Well, we just replace all the electronics with connected solution consisting of modules assmebled on a bread board. This has been an economical choice since wifi module combined with a smartphone replace all the command part of the system (electronic board, lcd screen, etc).
Trainer resistance driver
The resistance of the cross trainer is obtained by an electro-magnet driven by PWM. Driver architecture were simply taken from the original pcb: mainly a power mosfet and LC filter
Modular board
Once driver part is done, the wifi module is added. A gpio will be used to ouput the PWM signal with a transistor for power conversion. The assembly is simply done by soldering all this on a bread board.
Two holes are drilled to let the board being fastened in place of original pcb.
The interface is a web app
Control panel is made of a simple ESP8266 wifi module. The module is programmed in AP mode and host a small web app. This webapp enables to control one gpio which drive the electro-magnet at the end.
Some technical aspects :
- A user guide is automatically displayed once you connect to AP (captiv eportal)
- A websocket channel is used to control the resistance in real time
- Dynamic display is made in javascript
The webapp enables to choose the duration and difficulty of the training session. We could easily imagine something more sophisticated but we wanted to keep things simple.
Open Cross ?
Nowadays, retrofit can be an economical option when repairing things and the more we have technological ressources, the more it is true. That is why this webapp called "open cross" is let available and open source. May it helps others making similar projects and spare some devices being wasted.
