/**
* Initialize PWMs given a channel.
*
* <p>This method is private and is the common path for all the constructors for creating PWM
* instances. Checks channel value ranges and allocates the appropriate channel. The allocation is
* only done to help users ensure that they don't double assign channels. $
*
* @param channel The PWM channel number. 0-9 are on-board, 10-19 are on the MXP port
*/
private void initPWM(final int channel) {
checkPWMChannel(channel);
m_channel = channel;
m_port = DIOJNI.initializeDigitalPort(DIOJNI.getPort((byte) m_channel));
if (!PWMJNI.allocatePWMChannel(m_port)) {
throw new AllocationException("PWM channel " + channel + " is already allocated");
}
PWMJNI.setPWM(m_port, (short) 0);
m_eliminateDeadband = false;
UsageReporting.report(tResourceType.kResourceType_PWM, channel);
}
/**
* Get the value from a digital input channel. Retrieve the value of a single digital input
* channel from the FPGA.
*
* @return the status of the digital input
*/
public boolean get() {
ByteBuffer status = ByteBuffer.allocateDirect(4);
// set the byte order
status.order(ByteOrder.LITTLE_ENDIAN);
boolean value = DIOJNI.getDIO(m_port, status.asIntBuffer()) != 0;
HALUtil.checkStatus(status.asIntBuffer());
return value;
}
/**
* Free the PWM channel.
*
* <p>Free the resource associated with the PWM channel and set the value to 0.
*/
public void free() {
if (m_port == 0) return;
PWMJNI.setPWM(m_port, (short) 0);
PWMJNI.freePWMChannel(m_port);
PWMJNI.freeDIO(m_port);
DIOJNI.freeDigitalPort(m_port);
m_port = 0;
}
/**
* Set the bounds on the PWM pulse widths. This sets the bounds on the PWM values for a particular
* type of controller. The values determine the upper and lower speeds as well as the deadband
* bracket. $
*
* @param max The max PWM pulse width in ms
* @param deadbandMax The high end of the deadband range pulse width in ms
* @param center The center (off) pulse width in ms
* @param deadbandMin The low end of the deadband pulse width in ms
* @param min The minimum pulse width in ms
*/
protected void setBounds(
double max, double deadbandMax, double center, double deadbandMin, double min) {
double loopTime = DIOJNI.getLoopTiming() / (kSystemClockTicksPerMicrosecond * 1e3);
m_maxPwm = (int) ((max - kDefaultPwmCenter) / loopTime + kDefaultPwmStepsDown - 1);
m_deadbandMaxPwm =
(int) ((deadbandMax - kDefaultPwmCenter) / loopTime + kDefaultPwmStepsDown - 1);
m_centerPwm = (int) ((center - kDefaultPwmCenter) / loopTime + kDefaultPwmStepsDown - 1);
m_deadbandMinPwm =
(int) ((deadbandMin - kDefaultPwmCenter) / loopTime + kDefaultPwmStepsDown - 1);
m_minPwm = (int) ((min - kDefaultPwmCenter) / loopTime + kDefaultPwmStepsDown - 1);
}
