PIC18F4550 with spectrometer

[ferrousduke]

ok there's a spectrometer USB4000 from Ocean optics. datasheet is attached here. I want some serious help here.

project task and working:

1. USB4000 scans the optical light., with the capabality of scanning the whole spectrum in 3800 us, the data has to be sent to 18F4550.

2. it should send the data every ~4 ms. 18F4550 should compare the data and pwm is set accordingly.

can I have tentative idea of the interface? In datasheets of USB4000 its given that USB interface has a bulk transfer which means its for big files.

datasheet:

http://www.oceanoptics.com/technical/engineering/USB4000%20OEM%20Data%20Sheet.pdf

regards
Dharmesh

[Ttelmah]

You will have to use the RS232 interface, not the USB interface. PIC's are _slave_ USB devices, as is this unit. Slaves, cannot talk to slaves.
The fastest the RS232 will run, is 230400bps. With _care_ a PIC should be able to receive at this rate. This is still going to take 300mSec to transfer the whole spectrum (or you might use the compression mode - Page41), which should bring it down to about 200mSec.
So, 'no way' are you going to be able to scan the data every 4mSec....
To implement a USB master, you will need something like the FTDI Vinculum, or just use a PC (a 'single board' PC, can be had now for under £60, even in 'ten off' quantities, and using something like a compact Linux on this, will 'run rings' round any PIC solution...). If the quantities are going to be large, then it'll be worth spending the very significant development time to implement a master USB device. Otherwise, it'll be far cheaper, to use the embedded PC.

Best Wishes

[ferrousduke]

ok. will use RS232 interface. mm what abt GPIO's? can use for data transfer to PIC?

[ferrousduke]

mm Is there anyone? please help..