"""
-------------------------------------------------------------------------------------------
	(C)2008 Nuria Pujol Vilanova <nuriapujolvilanova@gmail.com>	

	USB comunication module for USB4000 Device (Ocean Optics) in Python.
				OpenDevice
				ResetDevice
				SentIntTime
				GetSample

	GPL License
-------------------------------------------------------------------------------------------
"""

import usb
from pylab import*

def OpenDevice(id=0x2457): #id= hexadecimal identifier
	"""
	---------------------------------------------------------------------------
	OpenDevice(id=0x2457)

	DESCRIPTION:

	Return a HandleDevice varible related with a USB device that has the same 
	'id' identifier.
	(HandleDevice Object is the only able to write and read in USB comunication)
			
	ARGUMENTS:		
	
	id -- hexadecimal idVendor identifier (default =0x2457) 
	---------------------------------------------------------------------------	
	"""
	buses = usb.busses()
	for bus in buses :
		for device in bus.devices :
			if device.idVendor == id: 
				print "USB4000 Device Found"
				dev=device
			elif device.idVendor == 0: #USB port without any device
				pass
			else:
				print "Other type of Device Found"
				
	handle= dev.open()
	return handle

def ResetDevice(handle):#handle device
	""" 
	---------------------------------------------------------------------------
	ResetDevice(handle)

	DESCRIPTION:

	Reset the comunication. Non output.

	ARGUMENTS:	
			
	handle - HandleDavice Object related to comunication to reset. 
	Object returned by OpenDevice
	---------------------------------------------------------------------------
	"""
	handle.reset()
	
def SetIntTime(handle,itime):
	"""
	---------------------------------------------------------------------------
	SetIntTime(handle,itime)
	
	DESCRIPTION:

	Write new integration time value on the device. Non output.
	(this function should be improved)

	ARGUMENTS:		
			
	handle - HandleDavice Object related to device to set new integration time. 
	Object returned by OpenDevice
	
	itime -  New integration time in INT format.
	---------------------------------------------------------------------------
	"""
	vector=[]
	
	while itime != 0:
		number=itime-((itime/2)*2)
		vector.append(number)
		itime = itime/2 	
		
	vector = vector + ([0]*(32-len(vector)))
	vector.reverse()
	
	def elevat(x):return 2**x
	
	pot1=map(elevat,range(0,8)*4)
	pot1.reverse()
	
	buf=[vector[i]*pot1[i] for i in range (len(vector))]
	
	def sum(seq):
			def add(x,y):return x+y
			return reduce(add,seq,0)

	MSW_MSB=sum(buf[0:8])#Byte 4
	MSB_LSB=sum(buf[8:16])#Byte 3
	LSW_MSB=sum(buf[16:24])#Byte 2
	LSW_LSB=sum(buf[24:32])#Byte 1

	buf_tx=chr(0x02)+chr(LSW_LSB)+chr(LSW_MSB)+chr(MSB_LSB)+chr(MSW_MSB)
	o=handle.bulkWrite(0x01,buf_tx)

def GetSample(handle,itime):
	"""
	---------------------------------------------------------------------------
	GetSample(handle,itime)

	DESCRIPTION:

	Return a single adquisition in a vector (3840 values)

	ARGUMENTS:	
	
	handle - HandleDavice Object related with the device to get samples from. 
			
	itime - Integration time to use in sample adquisition
	---------------------------------------------------------------------------
	"""
	command =chr(0x09)
	o=handle.bulkWrite(0x01,command)

	b0=handle.bulkRead(0x86,2048,itime)
	b4=handle.bulkRead(0x82,5632,itime)
	sincro=handle.bulkRead(0x82,1)#Non usefull data but has to be read
	data=b0+b4
	
	data_LSB=[((256+data[2*i])&0xFF) for i in range(len(data)/2)]
	data_MSB=[((256+data[2*i+1])&0xFF)<<8 for i in range(len(data)/2)]

	sample=[data_LSB[i]^data_MSB[i] for i in range(len(data_LSB))]
	
	return sample

def main():
	"""
	---------------------------------------------------------------------------
	DESCRIPTION

	Plot sample data obteined from USB4000

	DEFAULT ARGUMENTS VALUES:	
	
	handle - HandleDavice Object with idVendor 0x2456 

	itime - 4000us
	---------------------------------------------------------------------------
	"""
	itime=400000
	handle=OpenDevice()
	ResetDevice(handle)
	SetIntTime(handle,itime)
	lectura=GetSample(handle,itime)
	
	plot(lectura)
	show()
	
if __name__ == '__main__':
	main()