Society of Robots - Robot Forum

Electronics => Electronics => Topic started by: Del on June 29, 2007, 01:45:27 PM

Title: How to connect USB devices to Serial/Parallel Port?
Post by: Del on June 29, 2007, 01:45:27 PM

Hi,

Is there something to connect USB devices to a computer's serial or parallel port?
(For an old laptop without any USB ports.)

Something like the "opposite" of this:

http://www.parallax.com/detail.asp?product_id=28030 (http://www.parallax.com/detail.asp?product_id=28030)

Thanks

 :)

Title: Re: How to connect USB devices to Serial/Parallel Port?
Post by: rgcustodio on June 29, 2007, 02:26:43 PM

Buy a PCMCIA card with USB ports. Most laptops that I've used have PCMCIA ports. Most likely your laptop will have one too. Verify that your PCMCIA port can handle Cardbus as most PCMCIA-to-USB card require Cardbus. That is a safe bet, I have one and works like a charm on Windows and in Linux.

If you do find a USB to serial/parallel solution, the concern will be throughput. USB can handle up to 480 megabits per second, while serial can theoritically handle 1megabit only. So it'll be painfully slow.

Title: Re: How to connect USB devices to Serial/Parallel Port?
Post by: Del on July 02, 2007, 11:39:16 AM

Hi rgcustodio, thanks for the reply.  :)

Unfortunately, the laptop doesn't support CardBus.
I have a CardBus USB Card and it didn't work :'( . 

That's why I was hoping to find something I could just plug into the serial or parallel port.

I don't think throughput would be much of an issue,
since I'm just looking to connect a PIC and/or AVR programmer to it.

Are there any other options?  ???

Thanks!  :)

Title: Re: How to connect USB devices to Serial/Parallel Port?
Post by: Steve Joblin on July 02, 2007, 12:52:34 PM

I don't understand... I thought that PIC's and AVR's were programmed serially... the problem was that most new laptops don't have serial ports anymore, hence the need for USB to Serial Converters..  Can't you just connect a serial cable from your computer to the programmer?  You don't even need to deal with USB.  What am I missing?

Title: Re: How to connect USB devices to Serial/Parallel Port?
Post by: Robotboy86 on July 02, 2007, 08:34:29 PM

To be honest, I don't think they are compitable in the way you want.

USB is high bandwith and high speed, serial isn't so much so..

I tried to think of a solution for you, but I can't...  Sorry man :( Mini-itx boards are super cheap and overly powerful for a robot controller..   and with expansion ports you can get 6 serial ports per board even.  It also comes with usb ports and a PCI Card slot if more serial is needed, or you want wifi or anything else..


I will keep searching for you though buddy.

Title: Re: How to connect USB devices to Serial/Parallel Port?
Post by: Robotboy86 on July 02, 2007, 08:36:34 PM

Actually, why not get a usb to serial adapter, and simply plug the serial end into the laptop and the usb to the other part?  It should work both ways..   wouldn't it??

Title: Re: How to connect USB devices to Serial/Parallel Port?
Post by: Del on July 03, 2007, 11:44:09 AM

Quote

"Can't you just connect a serial cable from your computer to the programmer? 
You don't even need to deal with USB."

Hi Steve,

I have this PIC programmer, which connects to a PC via USB only:

http://www.microchipdirect.com/productsearch.aspx?Keywords=PICkit+2+Microcontroller (http://www.microchipdirect.com/productsearch.aspx?Keywords=PICkit+2+Microcontroller)

and I'm looking to get this AVR programmer, which also connects to a PC via USB only:

http://www.atmel.com/dyn/products/tools_card.asp?family_id=607&family_name=AVR+8%2DBit+RISC+&tool_id=3808 (http://www.atmel.com/dyn/products/tools_card.asp?family_id=607&family_name=AVR+8%2DBit+RISC+&tool_id=3808)

I'm not sure that it always works to connect the microcontroller directly to a PC's serial port.
I'm quite confused about what is required. I get the impression that the microcontroller
needs to be preloaded with a bootloader in order to program them directly via the serial/parallel port.
Otherwise, the manufacturer's programmer (like the ones above) is needed? Is this true?

Quote

"Actually, why not get a usb to serial adapter, and simply plug the serial end into the laptop and the usb to the other part?"

Hey, good question Robotboy! Does anybody know if that would work?

Thanks

Title: Re: How to connect USB devices to Serial/Parallel Port?
Post by: dunk on July 03, 2007, 07:34:28 PM

Quote

Quote

"Actually, why not get a usb to serial adapter, and simply plug the serial end into the laptop and the usb to the other part?"

Hey, good question Robotboy! Does anybody know if that would work?

it definitely would not work i'm afraid.
a USB port on a computer is a USB Host port.
a USB port on a peripheral (keyboard, mouse, PIC programmer, USB to serial adapter, USB cafe warmer, etc) is a USB Device.
you cannot connect 2 USB devices together. you can only connect a device to a host port. the host port controls the connection and requires some substantial processing power.

dunk.

Title: Re: How to connect USB devices to Serial/Parallel Port?
Post by: robotvisionary on July 09, 2007, 10:24:07 PM

Quote from: mp on June 29, 2007, 01:45:27 PM

Hi,

Is there something to connect USB devices to a computer's serial or parallel port?
(For an old laptop without any USB ports.)

Something like the "opposite" of this:

http://www.parallax.com/detail.asp?product_id=28030 (http://www.parallax.com/detail.asp?product_id=28030)

Thanks

 :)

You want something like this.
http://www.compusa.com/products/product_info.asp?pfp=cat3&product_code=309975&Pn=Serial_to_USB_Adapter (http://www.compusa.com/products/product_info.asp?pfp=cat3&product_code=309975&Pn=Serial_to_USB_Adapter)

it is very good small at an a reasonable price (I think). ???

 :) I have One.  :)

Title: Re: How to connect USB devices to Serial/Parallel Port?
Post by: dunk on July 10, 2007, 06:21:10 AM

Quote

You want something like this.
http://www.compusa.com/products/product_info.asp?pfp=cat3&product_code=309975&Pn=Serial_to_USB_Adapter

hi robotvisionary,
you are suggesting exactly the same thing as suggested 4 posts earlier.

it definitely would not work i'm afraid.
a USB port on a computer is a USB Host port.
a USB port on a peripheral (keyboard, mouse, PIC programmer, USB to serial adapter, USB cafe warmer, etc) is a USB Device.
you cannot connect 2 USB devices together. you can only connect a device to a host port. the host port controls the connection and requires some substantial processing power.

the device you linked to is for connecting a serial device to a computer's USB port,
not for connecting a USB device to a computers serial port.
there is a big difference.

sorry to give you a hard time but did you actually read this thread?

dunk.

Title: Re: How to connect USB devices to Serial/Parallel Port?
Post by: robotvisionary on July 10, 2007, 08:38:16 AM

Honestly no i just though of mine. I though that was what he was askin like for the $50 dollar robot.

Title: Re: How to connect USB devices to Serial/Parallel Port?
Post by: Admin on July 11, 2007, 05:53:36 PM

Plus, robotvisionary, that adaptor is 2x too expensive :P

Title: Re: How to connect USB devices to Serial/Parallel Port?
Post by: robotvisionary on July 12, 2007, 06:26:24 AM

Admin-
Were can I buy one that works.

Title: Re: How to connect USB devices to Serial/Parallel Port?
Post by: Admin on July 12, 2007, 06:59:40 AM

Any computer store should have them. I paid like $16 for mine if I remember correctly.

Title: Re: How to connect USB devices to Serial/Parallel Port?
Post by: Del on July 13, 2007, 10:32:20 AM

So, getting back to the original question (wink, wink, nudge, nudge)...  ;)

Am I correct to assume that this can't be done?  ???

(Specifically, connecting a USB programmer to the serial (or parallel) port of a computer.)

Thanks  :)

Title: Re: How to connect USB devices to Serial/Parallel Port?
Post by: dunk on July 16, 2007, 05:55:25 PM

you are correct.
barring considerable modification of the USB programmer,
this can't be done.

dunk.