On 2/12/2019 3:53 AM, bobwolf wrote:
The PRU task period is typically 3-5 uS, which would be a maximum count
frequency of 200 to 300 KHz. I'd want a decente safty margin to avoid
missed pulses and probably wouldn't want to have a count frequency over
50-75 KHz.
Whether this is fast enough depends on your machine details (eg: encoder
counts per revolution and your rapid speeds).
ok fantastic
a 3000rpm motor with 250cpr (1000 in quadrature) is 50kHz...
theoreticaly can i use 6 motor (50kHz x 6 = 300kHz) at maximum rapid speed?
or can all the motor (in theory) "run" at 200/300kHz?
The main problem using 6 encoders would be finding enough free PRU
direct input pins. Adding additional encoder instances to the PRU task
list will not significantly affect performance, and the 3-5 uS task
period mentioned previously should be more than enough time for 6
encoder instances along with other typical tasks (eg: stepgen & PWM).
--
Charles Steinkuehler
[email protected]
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website: http://www.machinekit.io blog: http://blog.machinekit.io github:
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