New Remote Control

(radio and/or Wired)

August 31, 2019

My new Remote Control box for the F7, Tender, NB1, and Mikado (in Push mode).

Wired versions have a 4-wire full-duplex UART interface operating at 9600 baud.
The transmitter sends out 2-byte packets every 1/37 seconds for the 12 inputs.
The LED display updates when a single byte is received from the controller.

Note: Some switches are dual function. So 8 switches provide 12 inputs.

And this is a radio version of the same. But notice it is upside down compared
to the wired box shown above. This is because it is from a newer vintage.

Internally there is a stack of two circuit boards. The switch/LED board,
and a cheap CPLD board that provides the logic functions.

Radio versions include an RFM69 radio module missing from this board as well as
a battery control IC that is also missing. Wired versions don't need a battery.

You can see how the application board joins to the generic CPLD board with 4 headers.
The switch/radio board simply plugs onto the CPLD board.

And here is yet another version. This is a "UART" version. It is used inside
a locomotive and has no user controls. It communicates with the locomotive's

Notice that this one is smaller and has less connectors from the previous.
It also has a radio module attached. The same radio is used in the handheld
boxes as well.


The Apply/Release and the Forward/Reverse switches are momentary center-off.
The switches for Number board lights, Classification lights, Service lights, and
Train line are just simple on-off switches.

The Headlight switch is center-off and in the low position operates the Mars light.
The Bell switch is center-off, but is momentary in the low position for the Horn.

LEDs are Red, Orange, Yellow, Green, Blue, and Violet, and indicate
High Current, Dynamic Braking, Low Battery Voltage, Forward, Reverse, and Standby.

Note: The ribbon wire seen here is only conveying 4 lines: +3.3v, GND, RX, and TX.

The CPLD board can be purchased from places like Amazon.
The other board is custom and is generally not available.