Does the quadrature decoder of nRF51 supports AEDR-8300 encoder?

[wyn]

Hello,

I am new on nRF51 and i would like to have a function to read the rotary position of motor in any rotary direction by adding a codewheel and a two channel reflective optical encoder, like AEDR-8300. The output of the two channels forms four phases with 90 degree shift per each phase, see page 3 of the document below for the waveform, when motor rotates in one direction the position reading is increased and the reading is decreased if the motor rotates in opposite direction . Does the quadrature decoder of nRF51 accept this waveform?

www.jameco.com/.../1548289.pdf

Thanks, wyn

[Sigurd]

Hi,

I don't think that should be any problem. It uses a standard 90 degree state width, so the waveform should be supported.

[wyn]

Thanks. Is the LED pin used for pwm control for power saving? in my usage encoder's led was fed by vdd with resistor directly.

[Sigurd]

Yes, the LED pin on the QDEC is used to control(turn off/on) the LED on the AEDR-8300 in order to keep the power levels to a minimum. On this infocenter link you can read more about it:

"The LED output follows the sample period, and the LED is switched on a given period before sampling and switched off immediately after the inputs are sampled. The period the LED is switched on before sampling is given in the LEDPRE register."

[wyn]

thanks a lot.

[wyn]

Hello,

Is the minimum sampling period of nRF51 series is 128 us? It looks like the sampling rate is too slow to detect the rotary motion for servo control with phase change rate over than 50000 phase per second. Is there any other chip contain better quadrature decoder suitable for servo control?

Thanks, Wayne