Posted by Angelo Rossi on October 3, 2011 at 10:37am
Hi,I measured a PWM output on sparkfun ATmega1280 and I found that when system is not armed all pwm outputs are 50 Hz, 1 ms, when I arm the system I experienced a variable frequency pwm output form 200 Hz to 300 Hz with duty cycle depending on the radio command. Is that normal? ThanksAngelo
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(Having looked at the implementation in APM_RC.cpp) Why isn't the timer/counter's 'TOP' value just reduced to 5000 rather than having that 'Force_Out0_Out1' jazz? Manipulating the timer/counter register to 'skip' over part of the timing seems unnecessary and terrifying.
ESCs dont typically use a clock pulse for sync so can take any frequency upto (i believe) 450hz ish. After that the 2ms maximum pulse width begins to blend into a constant high.
Replies
(Having looked at the implementation in APM_RC.cpp) Why isn't the timer/counter's 'TOP' value just reduced to 5000 rather than having that 'Force_Out0_Out1' jazz? Manipulating the timer/counter register to 'skip' over part of the timing seems unnecessary and terrifying.
Yeah, that's "Instant PWM" kicking in.