Design
Tether uses an encoder to detect the rotation of the reel with the wire, giving an accurate measure of the length extended. The joystick potentiometer, through which the wire is drawn, is used to measure the angle of the wire. These can be used to measure the position of the end of the wire. The wire is a braided pair, which is connected to a set of buttons on the handheld gripper.
Components
Board design
The board runs off a 3.7 V LiPo battery, and includes a charging circuit for the battery. The voltage is regulated by the Teensy, and the regulated voltage powers the Bluetooth module. The Serial 2 pins of the Teensy are connected to the BlueSMIRF module, at 115200 baud. The encoder is connected to interrupt pins 4 and 6, with an internal pull-up resistor activated. The potentiometers are connected to analog input pins 0, 1 and 2. Analog input pin 9 connects to the buttons on the gripper, and has the internal pull-up activated.
The board was printed using a home-etching process.
The board was printed using a home-etching process.