Tweening

Please take a look to the following piece of code

Const FPS = 60

Global FramePeriod%		; main game loop timing
Global FrameTime%
Global FrameElapsed%
Global FrameTicks%
Global FrameTween#

Global ProgramEnd% = False

Graphics3D 640, 480, 16, 0
SetBuffer BackBuffer()

camera = CreateCamera() : MoveEntity camera, 0, 0, -10
light = CreateLight()
cube = CreateCube()

Frame_Init()

Global dpitch#
Global dyaw#
Global droll#

Global velpitch# = 0
Global velyaw# = 180
Global velroll# = 0

start_time% = -1

While Not ProgramEnd


	If KeyHit(1) Then ProgramEnd = True
	Frame_Capture()
	For FrameLimit = 1 To FrameTicks
		FrameTime = FrameTime + FramePeriod
		If FrameLimit = FrameTicks Then
			CaptureWorld
		EndIf
		dpitch = velpitch * 1/FPS
		dyaw = velyaw * 1/FPS
		droll = velroll * 1/FPS
		TurnEntity cube, dpitch, dyaw, droll
		UpdateWorld
	Next
	RenderWorld FrameTween
	If start_time < 0 Then start_time = MilliSecs()
	If MilliSecs() - start_time <= 1000
		y = EntityYaw(cube)
	Else
		velyaw = 0
	EndIf
	Text 0, 0, "Yaw = " + y
	Flip
	
Wend

Function Frame_Init()

	FramePeriod = 1000 / FPS
	FrameTime = MilliSecs () - FramePeriod
	
End Function

Function Frame_Capture()

	Repeat
		FrameElapsed = MilliSecs () - FrameTime
	Until FrameElapsed
	FrameTicks = FrameElapsed / FramePeriod
	FrameTween = Float (FrameElapsed Mod FramePeriod) / Float (FramePeriod)
	
End Function

I want to have my entities to move in terms of velocities. The question is:
What is the velocity of Y-Axis, velyaw, in order to get the Cube rotated exactly 180 degrees within 1 second?
If you run the program you will see that I don't get the desired result setting the velyaw to 180 degrees/sec. OK I know that I am wrong but I don't know where!

Thanks