|5,6||Coupler load sensors|
|14 (A0)||Track voltage monitor|
|15 (A1)||Motor load sense|
|16-19||Additional: digital/analog/touch inputs; ditigal outputs|
|20-23||Lights/Smoke (digital or PWM)|
($1.14) Power for the onboard electronics will be provided by DC on the track rails. The exact voltage can vary, and we need to provide a regulated 5VDC for the electronics. I am using an LM2596 DC-DC converter which will be suitable for track voltages between 8-35VDC. A multimeter will be required to adjust the module to the desired 5VDC output, then a dab of paint can be put on the adjustment screw to lock it in place.
($4.45) Bluetooth control is enabled by a serial module such as the HC-06. These may be found on Ebay for a low cost, but generally ship from China and may take several weeks to arrive. Connection to the Teensy is as follows:
VCC -> 3.3V
GND -> GND
TXD -> RX1
RXD -> TX1
Alternates: HC-05, HM-10, HM-11
($0.50) Control of the locomotive motor will be handled by an L293D DC motor controller. This chip can control two motors but will only handle a maximum of 1.2A of current (possibly only 0.6A per channel?) so I will need to check if the locomotive motors fall within this range. This chip can also be found cheaply on Ebay.
Controlling the Speed of DC Motors
Complete speed/direction example
Discrete logic inverter
($0.11) For car detection on the layout, magentics will be used. An A3144 Hall effect sensor should be able to detect the passing of a magnet within a limited range.