[quote]which require a servo style signal not a PWM signal
Code: [Select][quote]which require a servo style signal not a PWM signalA servo style signal IS PWM.
Yes, but a servo control signal is a specifically defined subset of a typical true PWM signal,
frame rate (20-25msec) is 'standarized' amoung devices designed to receive 'servo commands'.
QuoteYes, but a servo control signal is a specifically defined subset of a typical true PWM signal, So you confirmed what we have been saying: the servo signal is necessarily PWM and a PWM signal isn't necessarily a servo signal.Agreement is good. Quoteframe rate (20-25msec) is 'standarized' amoung devices designed to receive 'servo commands'. I think you have plenty counter examples of that in this thread.I'm not so sure of that. I've read several opinions and statements here, but I've yet to see a link to a datasheet for a ESC that was designed to handle both standard servo signals and some propritary non standard PWM switching and duty cycle control signal. Not saying one doesn't exist, but it would certainly not be a typical common ESC. I would like to read more details on real products offered, as there are likely to be applications where such higher performance control would be useful or required.
I'm not so sure of that.
QuoteI'm not so sure of that.High resfreshrate ESC, FL6A FAST PWM ESCUp to 600Hz PPM inputhttp://www.flytron.com/multicopter-parts/178-fl.htmlServo 560Hzhttp://www.amainhobbies.com/product_info.php/cPath/61_100_2163_2165/products_id/207985/n/MKS-DS-8910A-Titanium-Gear-Digital-High-Speed-Mini-Tail-ServoServo Frequency and Center Pulse Width Information http://www.ronlund.com/rcheli/HELP_SERVO_PULSE.htmlUsing standard ESC's with high refresh rateshttp://wiki.openpilot.org/display/Doc/TurboPWM+ESC%27s#TurboPWMESC%27s-Recommended%26nbsp%3BESCsettings
How do I know if my ESCs are compatible?The only way to test it is to apply different input PWM frequency signals, make them change from low to high, and vice-versa. Check the motor response (notice how fast it achieves the desired RPMs after the input data changes, using tachometers). You should also check if it responds reliably, does not lose the sync, etc.
I don't see a datasheet from an original manufacture stating it's designed to work at other then 'standard' servo update/pulse width control.
QuoteI don't see a datasheet from an original manufacture stating it's designed to work at other then 'standard' servo update/pulse width control.Many of the servos are analog: it takes the pwm pulse train through a low-pass filter to derive at a voltage signal (to be compared with a position sensor's output). Because of such, a higher pwm frequency will always work - but a lower frequency may not.
QuoteI don't see a datasheet from an original manufacture stating it's designed to work at other then 'standard' servo update/pulse width control.I was suprised when I started looking for datasheets for ESC's that I couldn't find any specification of the update/pulse width. The only thing I could find was Castle Creation (one of the top brands of ESC's) has announced an upgrade to their firmware that should make their ESC suitable for multirotors.So I could ask the same question to retrolefty:How do you know that the standard servo update/pulse is within the specifikations when there is none. ? <- smileyBecause a ESC sold with a standard servo control connector strongly implies that it is suitable for the 'standard' variable pulse width and frame rate specifications that the R/C hobby has been using for many decades now, unless they stated otherwise in their datasheet. As such I would not assume any operation far from that 'standard' timings unless also documented in their datasheet. I think (I presume) that this standard servo specification goes back to the good old happy days of ppm TX/RX.Of course, that's my point. This thread is about using R/C type ESCs at frame rates well above that 'R/C standard' which seems to be possible via hand testing of some units from some manufactures. I question was really about OEMs documenting/verifying operation at other faster framing rates.AFter we have got all the pcm/spcm/spread spectrum technic it seems like vendors are more relaxed about the specifications.for example if you look at the Spektrum DX8:http://www.spektrumrc.com/Products/Default.aspx?ProdID=SPMAR7610it states: High-speed 11ms frame rate.That's a start, that would mean they are rating their device able to support up to twice the framing rate, maybe other OEMs will also start documenting such specifications. And although there has been numerous complaints with this system, if have not heard of any having trouble with their standard ESC.
maybe other OEMs will also start documenting such specifications.
That's a start, that would mean they are rating their device able to support up to twice the framing rate, maybe other OEMs will also start documenting such specifications.
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