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US Digital is proud to support the 2012 FIRST Robotics Competition, a sensational sport challenging the minds of tomorrow's engineers and researchers!
The official 2012 FRC Kit of Parts FIRST Choice description can be found on the US FIRST website. Additional encoders can be purchased at the AndyMark store or directly from US Digital. Please mention that you are a FRC team when ordering to receive the FIRST discount.
See the E4P assembly instructions.
Use the provided cable(s). If you need other cabling options, browse our 4-pin cables.
E4Ps are incremental encoders outputting 2-channel quadrature. They are capable of measuring shaft position, speed and direction.
Most incremental encoders provide quadrature output signals. A single track optical disk encoder can provide speed information only. Adding a second track to the optical disk and offsetting it by 1/4 cycle from the first track is quadrature and provides two advantages:
Absolute encoders can determine their position at power up. Incremental encoders only show relative movement after power up and would require a homing cycle in some applications.
The encoders provided are 360 CPR. With 4X quadrature decoding, you get 1440 positions per revolution. Which gives you a unique position every 0.25 degrees. The maximum RPM for these encoders is 10,000 RPM.
Here is how maximum RPM is calculated:
For the E4P, the maximum output frequency is 60 kHz (60,000 cycles per second). A 360 CPR encoder produces 360 pulses on each channel per revolution. To solve for how fast the encoder's shaft must turn per second to reach the maximum output frequency, divide the maximum frequency by the pulses per revolution. 60,000 / 360 = 166 revolutions per second. To convert to RPM multiply by 60 (10,000 RPM).