Converting serial to parallel

[Elie777]

I am going to use a usb to serial cable. I need my pic 16f84 to give an output of 5 bits which will be the input for an encoder.

Can some help me know what components I need and how to write the code to convert from serial to parallel.

10x for any help.

[Ttelmah]

Read the manual on GETC.
If the PIC is to do anything 'more' than just read serial, and output it on a port, you would be much better off with a different chip, with a UART.
Minimum needed:

Reliable 5v supply.
Crystal or ceramic resonator, giving a stable frequency.
Pull up resistor on MCLR.
Resistor and trap diode from the TXD line on the USD module, feeding to a pin on the PIC.
A #use RS232 line, specifying this pin, the baud rate you want to use, and the 'INVERT' option (must be used, unless you add a proper RS232 buffer).
Getc the character, and write the value to a port.

However if the PIC has to do anything 'more' (reply to the PC for example), then you really need to find a PIC with a UART, and add a RS232 level translator (MAX232 for example).

Best Wishes

[FvM]

I guess, using an USB-to-parallel adapter (FT245 or FT2232) with respective FTDI software driver would be an easier way. Or an USB PIC to interface to USB directly.

[temtronic]

Ttelmah has most of the details for you,though your project description is a bit vague. Will the PIC read the encoder and transmit the data to the PC, or does the PIC get data from the PC and do 'something with it?
I built several serial to parallel 'boxes' using the PIC 16F84 to allow parallel printers to be used on serial ports, since serial ported printers can't be found anymore.
Ttelmah, is right, that if you choose a newer PIC, it'll be easier and nicer! One with a built in clock and UART (16F628,648 ?? I think) works very well and easy on the wallet.
The hardest part will be the USB-Serial 'box', be sure to test it using a loopback connector very well. Some do NOT always work correctly!.

[Elie777]

10x for your replies. I just need to take data from the pc and use it.

FvM I searched a lot for a usb to parallel adapter but I couldn't find one.

[Ttelmah]

The units FVM mentions, are USB to serial adapters, _with a parallel output option as well_. Designed for 'embedded' applications. Hence will not be found if you search for 'USB to parallel', but sound as if they would do what you want.

Best Wishes

[Elie777]

Ttelmah can u help me to write my code because I'm trying to learn programming on my own and I don't have enough time because I have to present the project after 2 days. I'm finding a lot of difficulty writing this code.

10x for any help.

[temtronic]

As a general rule, everyone here will help you IF you show effort in 'cutting your own code' and ask why this or that doesn't work right.
To expect anyone to do your homework is not appropriate. Your 'project' is NOT a 2 day event! First you have to design and develop a PC based solution to talk to the PIC. Depending on the PC platform that could be a simple 'terminal' program, either canned or homemade. Then there's that USB interface. Another HUGE task unless you're lucky to have code that works for your USB device.Wiring to the PIC can be fun...as all USB devices don't work like others..oh yeah don't forget about the RS-232 chips!
The PIC program could be the easiest part of your task. After spending a week or so to get the 'Hello World' working, you can progress to the 'serial to parallel' program. It's quite easy to do ONCE you've read and re-read the CCS C manual a few times and cut maybe 20-30 versions of the program. Be sure to use resistors for the LEDS or you'll burnout the PIC !
You are very fortunate to have tools available that make this homework easy. One is called the Internet, the other Google.There are thousands of examples of your homework already out 'there' so it's really easy to copy someone else's efforts.
None of those 'tools' existed 40 years ago when I taught myself PDP-11 asm, Z-80 asm, BASIC, COBOL, FORTRAN, 68HC11 asm, 1802 asm the list goes on and on. I've spent 10s of thousands of hours soldering, wirewrapping, keying in programs, flowcharting, reading, reading, reading.....
You learn best by doing and that will take TIME but you'll be smarter and enjoy YOUR accomplishments.

[bkamen]

[FvM]

[Ttelmah]

The problem with usb to parallel units in general, is that they emulate a centronics printer port, so many require an 'ack' from the printer (easy to bodge this though....). Also though potentially you could just 'print' a bit pattern to appear on the port, some software won't sent a 'line' till the EOL character is seen. Again easy to avoid provided you sent the data yourself, but a serial-parallel approach, is possibly a fraction 'easier' for the inexperienced. The FT2232, is particularly easy to use, doing exactly what was originally described, allowing you to send a character on the PC, to what it 'sees' as a serial port, and then presenting this data in parallel.
There are so many solutions to this, that it is almost 'infinite'. Could do it in hardware without a processor (shift register on a serial connection), software (18F2550), dedicated chip (FT2232), PGA, etc. etc.. It'd possibly be quite 'fun' to work out how many possible solutions there are. I'd suspect several hundred, all with fundamental differences...

Best Wishes

[Elie777]

Can I find in the market a usb to parallel adapter that will be recognized by the pc( lab view) as a parallel port where I can control each pin?

I asked in many computer stores and they told me I can't find usb to parallel. I can only find usb to serial.

[Wayne_]

[temtronic]

Accessing the parallel port is dependent on the OS. Any PC using Win98SE or older allows direct(register) access to ports..

XP pro can have direct access if your program gets into Ring0(needed for true realtime stuff)

Don't know about other versions as I only use those two OS.

I'm still unclear as to the OP statement 'I need my pic 16f84 to give an
output of 5 bits which will be the input for an encoder', as no reference to what encoder he's using or what the overall picture is.It's gotten 'muddied' through the replies...

[Wayne_]