USB to RS232

Hi,

I'm not sure those two together will meet your requirement.

You've posted in the Arduino space, are you looking to attach the Arduino serial pins to a PC via USB?

If so, then the functionality you need is just a USB-to-UART chip.

If you're looking to attach the Arduino serial pins to a RS232 device, then USB is not required, just a 'RS232 transceiver' chip.

If it is completely unrelated to Arduino and you're looking to create some adapter to connect a PC to a RS232 device then the functionality you need is a USB to UART chip, and a RS232 transceiver chip.

If you want two RS232 interfaces, a dual UART USB chip can be used (no need for a USB hub chip). and the RS232 transceiver chip(s).

I have the same doubt of you Shabaz. Then it is not a USB chip but a USB HUB chip, that makes the difference. As far as I know, from the hub you connect USB devices. To at least one piece is missing in the design idea.

Enrico

Ok....

The idea is to connect 7 RS232 connections. Then access them via Arduino (or similar type proto board) in the end.

I`m just starting with two channels for  testing. USB ---> TUSB2077APTRTUSB2077APTR-> FT232RL-REELFT232RL-REEL ---> ADM213EARUZADM213EARUZ 

In the end I would like to have Arduino --> TUSB2077APTRTUSB2077APTR->  FT232RL-REELFT232RL-REEL ---> ADM213EARUZADM213EARUZ

Now one thing to keep in mind each channel requires a separate ground so I will only have one channel per set ( FT232RL-REELFT232RL-REEL and ADM213EARUZADM213EARUZ)

Does this help?

Hi Tom,

If it's possible to sketch what you wish to do (and specify the end equipment and purpose too) it will make it easier to follow, rather than specifying parts, because then I need to go looking at what each part does.

The Arduino isn't a USB host, so it cannot attach to a hub to connect out to USB devices.  The Arduino plays a USB device role, not a host role (and technically not even that - the embedded programmer/debugger on the Arduino is the thing that is playing the USB device role).

Unless you're using some unusual Arduino that I'm not aware of (I'm assuming Arduino Uno, but there are hundreds of Arduino variants/copies out there, so I'm not sure).

Guy`s let me get back to you on this.

The first test we did was Arduino to USB proto board then into a 8 channel RS232 hub and everything worked great. We could read all the RS232 data from all channels.

Now for me the request is to make a shield to connect direct to the Arduino proto board. Let me check.

Thanks for the responces

T

If I understand, you've used a hub something like this (easysync) device, except you want 8 ports ?  I've use this previously, with good results.

It's been a while since I opened this up, I can look into my parts bin and tell you what chip is inside that does the 'magic' converting 1 USB into multiple RS232.  I think it was an FTDI chip, which is  common.  https://www.ftdichip.com/

"The idea is to connect 7 RS232 connections. Then access them via Arduino (or similar type proto board) in the end."

Perhaps take a look at the ATxmega A1U or A3U family of AVR 8-bit microcontroller which appear to have 8 / 7 USARTs to play with.

http://ww1.microchip.com/downloads/en/DeviceDoc/30010135D.pdf

Add some MAX232's and away you go.

Unfortunately the XMEGA A1U Xplained Pro evaluation kit only appears to break 5 of them out to headers but it may still be useful for proof of concept.

ATXMEGAA1U-XPRO - Evaluation BoardATXMEGAA1U-XPRO - Evaluation Board

It looks as if you want an Arduino with 8 RS232 ports.

The neatest way to do this is to use an FPGA - something fairly small will do. You can connect the FPGA to the Arduino via UART or SPI at logic level (care needed if it's a 5V Arduino).

If you need true RS232 ports at correct levels then you'll need level shifters like the TI device you mentioned.

The FPGA work will be challenging if you've never done any before, but you would be able to get true simultaneous operation of all 8 ports with buffering and good control of latency.

If you are more used to processors consider using a fast ARM based part which will be able to do 8 UARTs in software at 9600 baud quite easily.

As is so often the case, it would be much easier to make good suggestions if you would describe what you actually want to achieve in a bit more detail.

For example, you might be able to use an ST Nucleo board (NUCLEO-F429ZI would be suitable)

with a nice fast processor to do everything you need, including simulate 8 UARTS.

MK

Ok, Had a talk with the guy`s and here`s what they would like to see in the end.

• We will also need to produce a prototype PCB in the end. So I like to keep it simple the first go round.
• True simultaneous operation of all ports with buffering and good control of latency.

michaelkellett I like the idea of the FPGA I will look into this. I`m a little worried about the programming I`m not sure we have the skills/knowable at this point to pull this off. Are they easy to program? I have one guy here that is/has some knowledge of them

• If you are more used to processors consider using a fast ARM based part which will be able to do 8 UARTs in software at 9600 baud quite easily.(This was our original idea).

mp2100

Yes we used this version for the first testing and everything worked quite nice.

Hello Tom,

I quite like FPGAs - but then that's what I do quite a bit.

If this is a commercial project I could help you with FPGA design for money !

If not, then I'll be able to help a bit on E14 with some advice but in the end you'll need to do the actual work. As FPGA applications go this is not a bad one to start with - nothing too fast or horribly complex.

If you will make a lot of these the cost of the FPGA will be important, if only up to a few hundred then I would look at Lattice XP2 parts or Altera MAX 10, if lots and lots then look at Lattice ice40 parts.

Do you just need RX and TX on the RS232 or do you need some or all of the handshake pins as well ?

MK