def set(self, value):
"""Set the relay state.
Valid values depend on which directions of the relay are controlled by
the object.
When set to kBothDirections, the relay can be set to any of the four
states: 0v-0v, 12v-0v, 0v-12v, 12v-12v
When set to kForwardOnly or kReverseOnly, you can specify the constant
for the direction or you can simply specify kOff and kOn. Using only
kOff and kOn is recommended.
:param value: The state to set the relay.
:type value: :class:`Relay.Value`
"""
if self.port is None:
raise ValueError("operation on freed port")
if value == self.Value.kOff:
if (self.direction == self.Direction.kBoth or
self.direction == self.Direction.kForward):
hal.setRelayForward(self.port, False)
if (self.direction == self.Direction.kBoth or
self.direction == self.Direction.kReverse):
hal.setRelayReverse(self.port, False)
elif value == self.Value.kOn:
if (self.direction == self.Direction.kBoth or
self.direction == self.Direction.kForward):
hal.setRelayForward(self.port, True)
if (self.direction == self.Direction.kBoth or
self.direction == self.Direction.kReverse):
hal.setRelayReverse(self.port, True)
elif value == self.Value.kForward:
if self.direction == self.Direction.kReverse:
raise ValueError("A relay configured for reverse cannot be set to forward")
if (self.direction == self.Direction.kBoth or
self.direction == self.Direction.kForward):
hal.setRelayForward(self.port, True)
if self.direction == self.Direction.kBoth:
hal.setRelayReverse(self.port, False)
elif value == self.Value.kReverse:
if self.direction == self.Direction.kForward:
raise ValueError("A relay configured for forward cannot be set to reverse")
if self.direction == self.Direction.kBoth:
hal.setRelayForward(self.port, False)
if (self.direction == self.Direction.kBoth or
self.direction == self.Direction.kReverse):
hal.setRelayReverse(self.port, True)
else:
raise ValueError("Invalid value argument '%s'" % value)
def _freeRelay(port):
hal.setRelayForward(port, False)
hal.setRelayReverse(port, False)
hal.freeDIO(port)