Circuit to PC/PDA interfacing

[Jezhead]

Hi, I am student studying Electronics and Computing. For my final year project I have to design and construct a system for passive underwater tracking. In order to do this I need a circuit that calculates the time difference between four inputs and then sends this data into a PC or PDA. Once the data is in the PC or PDA some position fixing algorithms can be run and a location produced. So far I have design a logic array that calculates the time difference between the four inputs and written the position calculating program. However I am having real problems with the following:

1: I can’t work out how to transmit my time differences, which are digital numbers, into a PC or PDA across a USB cable. There are several USB interface chips available on the market but I can’t find any information on how to use them or how integrate them into a circuit anywhere.

2: I need to know if PDA’s can be connected to home made circuit boards through their USB ports. I know some PDA’s can be connected to digital cameras although there is no evidence of them being connected to anything else. The main manufactures, Compaq, Sony, Psion etc… are yet to respond to my requests for information which is a little worrying.

Any help, advice or general information anyone can provide would be much appreciated. Thank you for you time,

Jezhead.

 

[bmcculla]

To find information about USB interface chips just type the part number into Google the manufacturer's data sheet should be one of the top hits. Check out National's USBN9603 (they will send free samples through their website) and Cypress SL811HS(available on digikey).

As far as the PDA USB ports they might use the "USB on the go" standard which has different bus power specs.

 

[Jezhead]

Seems like you've pointed me in a new direction thanks, every little helps.

 

[frodus]

hey, I've already got this working on the palm. Use a PIC processor, program it to recieve the inputs (4 of them i take it?) and take those values and send them to the palm. THe EASIEST way to do this is with the serial port. Palm pilots and computeres have them already and they're easy to interface to. WHen you use USB, you're gonna run into interfacing and protocol problems.... use serial.

i might be able to help you with this (i have acess to a compiler/programmer at work)...if its worth my effort.

if you need help, PM me or mail me
frodus17 at yahoo dot com

 

[fat-tony]

Also, you can get micros that have USB functionality built right in. The Cypress EZ-USB 8051 series has pretty good USB support (as far as I know), and isn't too expensive.
**broken link removed**


I'm not sure if that'll work for a link.

 

[Nigel Goodwin]

MicroChip also produce a PIC with built-in USB, it's the 16C745, you can download sample code from MicroChip for it. It's also used in the new MicroChip 8/14 pin FLASH programmer, and you can download all the code (and diagrams) for that - both the PIC and PC ends.