SIO to USB for Mac OS/X ?

[Fletch]

I have a MacPro t work. If I can find an economical serial card I will test this for you.

 

Here's one another SIO2OSX user says he bought and it works, and is FTDI. It's German, so not sure what shipping, etc are from UK, but here is the link he gave me:

 

http://www.er-tronik.de/shop2/product_info...210d62d6c892343

 

I know that it is a pain trying to find the right adapter, and I'm sure that's why Steve at Atarimax.com created his own USB dongle.

 

The issue with most of the Serial dongles, is that they are not real time on any of the handshake/control lines. They work fine for "3-wire" serial applications where all you need is transmit, receive, and ground. However, to emulate SIO, you have to use one of the modem control lines, and the timing has to be accurate. The reason FTDI works is that it returns the modem status lines in every USB frame (or once per 1ms). The other dongles are making their driver poll for the lines, by sending a separate USB message and waiting for the reply, and the latency is more than the SIO emulation can handle.

 

With anybody who has a MacPro (not many I know), the other option which I'm pretty sure would work is using a PCIE 16550 Serial card. I'm pretty sure OSX has a 16550 standard. But that only helps MacPro users, and the cards aren't real cheap either.

[Sub(Function(:))]

That's the trick. The dongle I have works fine with my Mac, just not with SIO2OSX. This is known behavior and there is an explanation of the problems with some of them on the SIO2OSX web page. I understand the issue and that the FTDI chipset is what to aim for but my problem is not many (if any) sellers tell you that kind of detail in their ads.

 

I think it is something to do with response latency.

 

That is this time the RS232 pin responds to the signal from the PC. FTDI chips are quick to respond (or so they claim). Thus they can give good timing on the SIO bus. If you are only sending serial data to a modem or another PC I guess timings are not that important, But to the SIO bus it is.

 

I have seen some USB digital IO boards in Conrad (German version of Maplins or Tandy) that quoted something like 12 or 19 ms to respond to a change requested from the PC.

[atarimac]

Spookt,

From the other thread on performance of USB dongles with OSX, c0nsumer gave a link to the FTDI page I hadn't noticed before (http://www.ftdichip.com/Products/EvaluationKits/USB-Serial.htm), and at the bottom of it is a link for a UK supplier of a FTDI dongle: http://www.easysync.co.uk/.

 

I'm PM you as well.

 

Regards,

Mark

[belboz]

Here is a board I use that is great for USB -> SIO. FTDI based and cheap, plus its on a small PCB so you can just solder an SIO cables to the spots on the PCB.

 

http://www.sparkfun.com/commerce/product_i...products_id=718

 

$15 and you will need a mini usb cable if you don't have one (they have them for $4)

 

Works great with OS X, Linux, and Windows.

 

I have a command line based OS X program I wrote that supports ATR and exe files (single drive only). Was going to release something for free for Mac users (plus it compiles and works great on Linux too). Using it with the above board and it has worked very well for me.

 

If there are any Cocoa programmers out there who would like to help, drop me a PM.

[belboz]

Oh one note about the above board. It defaults to 3.3V so you have to unsolder a small jumper and solder a small wire to the 5V source on the board. Then you get the standard TTL level signals needed for the SIO port.

 

Great little board.

 

(not affiliated in any way with Sparkfun, just a customer)

[mellis]

Oh one note about the above board. It defaults to 3.3V so you have to unsolder a small jumper and solder a small wire to the 5V source on the board. Then you get the standard TTL level signals needed for the SIO port.

 

Great little board.

 

(not affiliated in any way with Sparkfun, just a customer)

 

Hi Belboz.

 

I purchased an FT232R board shortly after reading your post.

 

It has arrived, and I am about to modify it to operate at TTL levels (5V). If I am reading the data sheet correctly, it looks like I need to run a wire from VCC (pin 20) to VCCIO (pin 4). Is that the modification you made to get it to operate above 3.3V? Also, at what point did you desolder?

 

Thanks!

[mellis]

Oh one note about the above board. It defaults to 3.3V so you have to unsolder a small jumper and solder a small wire to the 5V source on the board. Then you get the standard TTL level signals needed for the SIO port.

 

Great little board.

 

(not affiliated in any way with Sparkfun, just a customer)

 

Hi Belboz.

 

I purchased an FT232R board shortly after reading your post.

 

It has arrived, and I am about to modify it to operate at TTL levels (5V). If I am reading the data sheet correctly, it looks like I need to run a wire from VCC (pin 20) to VCCIO (pin 4). Is that the modification you made to get it to operate above 3.3V? Also, at what point did you desolder?

 

Thanks!

 

I'm going to take a moment to reply to my own post.

 

Upon further inspection, it looks like there is a solder-pad right next to pin 15. It looks to me like Pin 17 is 3.3V out, and as shipped, that pin connects to Pin 4 (VCCIO) via that solder point. If I remove the solder from that point and run a wire connecting VCC (pin 20) to VCCIO (Pin 4), I think I'm in business.

 

Would you concur?

[belboz]

Sorry for the delay. Yep remove the little solder jumper to remove the 3.3V from VCCIO. Than run a tiny wire from VCC to VCCIO. And you will be in business.

[mellis]

Sorry for the delay. Yep remove the little solder jumper to remove the 3.3V from VCCIO. Than run a tiny wire from VCC to VCCIO. And you will be in business.

 

Thanks, Belboz. As they say, it's better to measure twice and cut once!