Usb <-> Rs485 - Electronic Circuits Projects Diagrams Free

Kryten · 18th May 2008, 01:30 PM

Hi
Is there anybody that has som schematics for a USB to RS485 converter??

petrv · 18th May 2008, 01:37 PM

No but I would take PIC18F2455 and MAX485, add crystal, connectors, a few capacitors and there you have an adapter. All that it will need is a firmware for the microcontroller ...

You can have a look at the Unicorn kit from blueroomelectronics

Kryten · 18th May 2008, 01:39 PM

Hmm sounds like a big box

Can it run on USB power?

petrv · 18th May 2008, 01:41 PM

if you use the SMD versions of the chips it won't be big. I don't see a problem running that on USB power.

Kryten · 18th May 2008, 01:43 PM

Cool Im looking in to it as we speak

blueroomelectronics · 18th May 2008, 01:50 PM

The FT232R has the schematic for a USB to RS485 converter in its datasheet.
FT232R

Kryten · 18th May 2008, 02:02 PM

They dont provied samples

petrv · 18th May 2008, 02:17 PM

Hi Bill,

I don't know how I end up advertising your kits again ...

I was thinking about the FTDI chip as well but personally I prefer the PIC.
Both solutions have their advantages and disadvantages of course.

Petr

blueroomelectronics · 18th May 2008, 02:43 PM

Hey I always appreciate the plug

I've used the FT232R and it's a nice chip. Would make an excellent USB to RS485 kit.

arhi · 18th May 2008, 05:27 PM

I used to use FTDI chips all the time .. and recently I decided to stop. I stopped when I found out that locally I can get FTDI chip for 8E and PIC18F4550 for under 7E .. so that simple truth removed FTDI chips from my order list. There is nothing FTDI can do that 18f4550 cannot (except, ok, ftdi is much smaller and use less power)

blueroomelectronics · 18th May 2008, 05:51 PM

FT232R
Pros no firmware or crystal needed, low power.

PIC18F2550 / 4550
Pros DIP package (if you don't want to solder a SOIC), and you get a nice microcontroller thrown in. I did find a FT232 emulator (firmware) on Xiaofan Chen's site.
Xiaofan's Blog: USB

petrv · 18th May 2008, 05:59 PM

I'd like to add that even if you do want to use SMD parts SOIC package (PIC18F2455/2550) is much easier to solder than FTDI chip in SSOP package, QFN is even more manual soldering unfriendly (I assume you don't have your own reflow owen ...)

arhi · 18th May 2008, 06:11 PM

@blueroomelectronics
I agree with pro's and con's but, how often do you make usb device without uC .. 90% of devices I made used FTDI in cooperation with uC on board. I usually do not pay attention on the cost, but when I noted that instead FTDI I can put 18f4550 I just stopped..

Quote:

Originally Posted by petrv

I'd like to add that even if you do want to use SMD parts SOIC package (PIC18F2455/2550) is much easier to solder than FTDI chip in SSOP package, QFN is even more manual soldering unfriendly (I assume you don't have your own reflow owen ...)

I never tried to manually solder FTDI

what I do is I put solder on pcb, glue the FTDI on top of that (using flux as a glue, as it is sticky while hot) and then I put it in normal house oven for few minutes... never failed

blueroomelectronics · 18th May 2008, 06:26 PM

I'm not a fan of soldering SOIC and such myself, the best solution I've found is the Schmartboard system. Soldered a TQFP with it just fine.

Ubergeek63 · 19th May 2008, 01:33 AM

Quote:

Originally Posted by arhi

I used to use FTDI chips all the time .. and recently I decided to stop. I stopped when I found out that locally I can get FTDI chip for 8E and PIC18F4550 for under 7E .. so that simple truth removed FTDI chips from my order list. There is nothing FTDI can do that 18f4550 cannot (except, ok, ftdi is much smaller and use less power)

Try writing to a thumb drive with a 4550...

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18th May 2008, 01:30 PM	(permalink)
Kryten	Usb <-> Rs485 Hi Is there anybody that has som schematics for a USB to RS485 converter?? __________________ Simplicity rules Good enought - its perfect ?? 2 Gig of free online backup space Are you a Chemist?

18th May 2008, 01:37 PM	(permalink)
petrv	No but I would take PIC18F2455 and MAX485, add crystal, connectors, a few capacitors and there you have an adapter. All that it will need is a firmware for the microcontroller ... You can have a look at the Unicorn kit from blueroomelectronics Last edited by petrv; 18th May 2008 at 01:40 PM.

18th May 2008, 01:39 PM	(permalink)
Kryten	Hmm sounds like a big box Can it run on USB power? __________________ Simplicity rules Good enought - its perfect ?? 2 Gig of free online backup space Are you a Chemist?

18th May 2008, 01:41 PM	(permalink)
petrv	if you use the SMD versions of the chips it won't be big. I don't see a problem running that on USB power.

18th May 2008, 01:43 PM	(permalink)
Kryten	Cool Im looking in to it as we speak __________________ Simplicity rules Good enought - its perfect ?? 2 Gig of free online backup space Are you a Chemist?

18th May 2008, 01:50 PM	(permalink)
blueroomelectronics	The FT232R has the schematic for a USB to RS485 converter in its datasheet. FT232R __________________ Bill Smart Kits build Smart People http://www.blueroomelectronics.com

18th May 2008, 02:02 PM	(permalink)
Kryten	They dont provied samples __________________ Simplicity rules Good enought - its perfect ?? 2 Gig of free online backup space Are you a Chemist?

18th May 2008, 02:17 PM	(permalink)
petrv	Hi Bill, I don't know how I end up advertising your kits again ... I was thinking about the FTDI chip as well but personally I prefer the PIC. Both solutions have their advantages and disadvantages of course. Petr

18th May 2008, 02:43 PM	(permalink)
blueroomelectronics	Hey I always appreciate the plug I've used the FT232R and it's a nice chip. Would make an excellent USB to RS485 kit. __________________ Bill Smart Kits build Smart People http://www.blueroomelectronics.com

18th May 2008, 05:27 PM	(permalink)
arhi	I used to use FTDI chips all the time .. and recently I decided to stop. I stopped when I found out that locally I can get FTDI chip for 8E and PIC18F4550 for under 7E .. so that simple truth removed FTDI chips from my order list. There is nothing FTDI can do that 18f4550 cannot (except, ok, ftdi is much smaller and use less power) __________________ http://www.it4um.com

18th May 2008, 05:51 PM	(permalink)
blueroomelectronics	FT232R Pros no firmware or crystal needed, low power. PIC18F2550 / 4550 Pros DIP package (if you don't want to solder a SOIC), and you get a nice microcontroller thrown in. I did find a FT232 emulator (firmware) on Xiaofan Chen's site. Xiaofan's Blog: USB __________________ Bill Smart Kits build Smart People http://www.blueroomelectronics.com

18th May 2008, 05:59 PM	(permalink)
petrv	I'd like to add that even if you do want to use SMD parts SOIC package (PIC18F2455/2550) is much easier to solder than FTDI chip in SSOP package, QFN is even more manual soldering unfriendly (I assume you don't have your own reflow owen ...)

18th May 2008, 06:26 PM	(permalink)
blueroomelectronics	I'm not a fan of soldering SOIC and such myself, the best solution I've found is the Schmartboard system. Soldered a TQFP with it just fine. __________________ Bill Smart Kits build Smart People http://www.blueroomelectronics.com