redux::frames Namespace Reference

Classes
class	Frame
class	FrameData
class	FrameListener

Functions
template<typename... T>
std::optional< std::tuple< FrameData< T >... > >	WaitForFrames (units::second_t timeout, Frame< T > &... frames)
template<typename... T>
units::second_t	MaxTimestamp (std::tuple< FrameData< T >... > frameData)

Detailed Description

Namespace holding classes relating to device data frames

Function Documentation

MaxTimestamp()

template<typename... T>

units::second_t redux::frames::MaxTimestamp

(

std::tuple< FrameData< T >... >

frameData

)

Returns the max timestamp from a tuple of FrameData objects. Most useful for getting the "latest" CAN timestamp from a result of WaitForFrames.

Parameters

frameData

value from WaitForFrames

Returns

the maximum timestamp

WaitForFrames()

template<typename... T>

std::optional< std::tuple< FrameData< T >... > > redux::frames::WaitForFrames	(	units::second_t	timeout,
		Frame< T > &...	frames
	)

Waits for all Frames to have transmitted a value. Either returns an std::tuple of FrameData<T>; representing the data from corresponding frames passed in (in the order they are passed in) or std::nullopt if timeout or interrupt is hit.

Code example:

// Keep in mind this code sample will likely cause timing overruns if on the main thread of your robot code.
// Device definitions:
redux::sensors::canandmag::Canandmag enc0{0};
redux::sensors::canandmag::Canandmag enc1{1};
 
// wait up to 40 ms for position and velocity data to come in from two Canandmags
auto data = redux::frames::WaitForFrames(40_ms, enc0.GetPositionFrame(), enc0.GetVelocityFrame(), enc1.GetPositionFrame());
if (!data.has_value()) {
  fmt::print("WaitForFrames timed out before receiving all data\n");
} else {
  redux::frames::FrameData<units::turn_t> posFrame;
  redux::frames::FrameData<units::turn_t> posFram1;
  redux::frames::FrameData<units::turns_per_second_t> velFrame;
 
  // populates the above FrameData variables with the received data (unpacks the tuple)
  std::tie(posFrame, velFrame, posFram1) = *data;
 
  // fetches the maximum timestamp across all received timestamps (the "latest" value)
  units::second_t maxTs = redux::frames::MaxTimestamp(*data);
 
  // prints the received frame value and how far behind the latest received CAN timestamp it was
  fmt::print("posFrame: {}, {}\n", posFrame.GetValue(), 
             (units::millisecond_t) (maxTs - posFrame.GetTimestamp()));
  fmt::print("velFrame: {}, {}\n", velFrame.GetValue(), 
             (units::millisecond_t) (maxTs - velFrame.GetTimestamp()));
  fmt::print("posFram1: {}, {}\n", posFram1.GetValue(), 
             (units::millisecond_t) (maxTs - posFram1.GetTimestamp()));
 
} 

Parameters

timeout	maximum seconds to wait for before giving up
frames	references to Frames to wait on. Position in argument list corresponds to position in the returned FrameData tuple.

Returns

a tuple of FrameData<T> representing the data from corresponding frames passed in or null if timeout or interrupt is hit.