Automatic vs. manual

[Fesh]

Instead of the self-made buzzer/button unit, I would like to use the TranzX AGT unit which is available here:
<https://www.ebay.de/itm//153839395353>

This Unit has 3 buttons: "-" and "+" for manual shifting, "A" for automatic. And a small LED display for the selected gear.
Looks perfect for this project - though I do not know how it is wired.

A similar item from the same vendor is 50% more expensive and has a different connector:
<https://www.ebay.de/itm/TRANZX-AGT-SCHALTHEBEL-/124091061927>

What do you think?


Found a video from TranzX AGT (automatic gear transmission):
<https://www.youtube.com/watch?v=vLHdEFU0ors>

[Jan Oelbrandt]

Funny that I never heard of the TranzX system before.
From what it looks like in the video it's (very) similar to what Shift4Me does, except that it uses a torque sensor.

First of all, concerning your question: a buzzer signal is highly recommended. It's needed to warn you when the shifting is being done, because you need to take the load off the chain for just a second. 

The 40€ type control unit looks neat. The plus/minus and A buttons will probably just short one of the colored wires. So that would be very easy to control the Arduino. The plus/minus code is already there, you'll just have to write a little extra code to control the auto/manual behaviour.
Maybe somebody here can help you on how the display is controlled...

Good luck and keep up posted on your build!

[Ed_R]

Good find Fesh, not an automatic system I knew of. According to the manual (link to pdf http://www.crservice.dk/EFLY/AGT%20vejle...ngelsk.pdf) it uses a gradient sensor. Interesting way of doing it but wouldn't be my choice. Cadence sensor is best and add torque or power if you want to get fancy.

The button unit does look ideal. However looking at the number of functions (3 buttons, 7 segment display and led) and only 8 wires I’m guessing it uses some kind of communication such as SPI. So the button unit would have its own microcontroller to decode the data and drive the outputs and send the button inputs back encoded as data.
If it wasn’t so expensive it would be worth getting it to find out although I think it’s very unlikely the buttons are wired directly. Would be a fun project to reverse engineer and work out the communication protocol but maybe easier to build your own.

[Fesh]

Good find Fesh, not an automatic system I knew of. According to the manual (link to pdf http://www.crservice.dk/EFLY/AGT%20vejle...ngelsk.pdf) it uses a gradient sensor. Interesting way of doing it but wouldn't be my choice. Cadence sensor is best and add torque or power if you want to get fancy.

Since this is used for a pedelec, of course it has a cadence sensor, and some TranzX equipped bikes also have a torque sensor. The gradient is always "on top"...

The button unit does look ideal. However looking at the number of functions (3 buttons, 7 segment display and led) and only 8 wires I’m guessing it uses some kind of communication such as SPI. So the button unit would have its own microcontroller to decode the data and drive the outputs and send the button inputs back encoded as data.

Since the calibration of the gradient sensor is signaled in the 7-segment unit (and not in the main LCD unit), this means there are bike configurations without LCD, or at least possible. I don't know where the gradient sensor is located - in the button unit or in the controller, but we can be sure it's not in the LCD.

If it wasn’t so expensive it would be worth getting it to find out although I think it’s very unlikely the buttons are wired directly. Would be a fun project to reverse engineer and work out the communication protocol but maybe easier to build your own.

One can probably open and re-wire the button unit.
Sure it would be nice to have the current gear shown on the LCD, but the primary reason for me to use it would be the 3 buttons in a nice, watertight case.