87 lines
3.5 KiB
Markdown
87 lines
3.5 KiB
Markdown
# Servo Library for ESP32
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This library attempts to faithfully replicate the semantics of the
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Arduino Servo library (see http://www.arduino.cc/en/Reference/Servo)
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for the ESP32, with two (optional) additions. The two new functions
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expose the ability of the ESP32 PWM timers to vary timer width.
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## License
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Copyright (c) 2017 John K. Bennett. All right reserved.
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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## Library Description:
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```
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Servo - Class for manipulating servo motors connected to ESP32 pins.
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int attach(pin ) - Attaches the given GPIO pin to the next free channel
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(channels that have previously been detached are used first),
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returns channel number or 0 if failure. All pin numbers are allowed,
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but only pins 2,4,12-19,21-23,25-27,32-33 are recommended.
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int attach(pin, min, max ) - Attaches to a pin setting min and max
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values in microseconds; enforced minimum min is 500, enforced max
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is 2500. Other semantics are the same as attach().
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void write () - Sets the servo angle in degrees; a value below 500 is
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treated as a value in degrees (0 to 180). These limit are enforced,
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i.e., values are constrained as follows:
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Value Becomes
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----- -------
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< 0 0
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0 - 180 value (treated as degrees)
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181 - 499 180
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500 - (min-1) min
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min-max (from attach or default) value (treated as microseconds)
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(max+1) - 2500 max
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void writeMicroseconds() - Sets the servo pulse width in microseconds.
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min and max are enforced (see above).
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int read() - Gets the last written servo pulse width as an angle between 0 and 180.
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int readMicroseconds() - Gets the last written servo pulse width in microseconds.
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bool attached() - Returns true if this servo instance is attached to a pin.
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void detach() - Stops an the attached servo, frees the attached pin, and frees
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its channel for reuse.
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```
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### **New ESP32-specific functions**
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```
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setTimerWidth(value) - Sets the PWM timer width (must be 16-20) (ESP32 ONLY);
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as a side effect, the pulse width is recomputed.
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int readTimerWidth() - Gets the PWM timer width (ESP32 ONLY)
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```
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### Useful Defaults:
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default min pulse width for attach(): 544us
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default max pulse width for attach(): 2400us
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default timer width 16 (if timer width is not set)
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default pulse width 1500us (servos are initialized with this value)
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MINIMUM pulse with: 500us
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MAXIMUM pulse with: 2500us
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MAXIMUM number of servos: 16 (this is the number of PWM channels in the ESP32)
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