MCS7840 based quad USB/RS232 port

[picitup]

Hi All

After obsessively adding native RS232 ports to all my kit, I'd like to share with you the purchase of a quad USB/Serial port.  It cost about £19.00.  It works really well and on the Asix web site, they seem to have drivers for pretty much every version of Windows including CE, the mac and linux:

http://www.asix.com.tw/products.php?op=pItemdetail&PItemID=110;74;109&PLine=74

I don't have all these operating systems, but all 4 ports installed fine on my Windows 7 64 bit laptop and my daughter's Windows 8.1 64 bit laptop.

I've taken the thing apart and added some piccies below.  As noted above, the main chip is the MCS7840 and the RS232 line drivers are  Sipex SP213 chips which have 4 drivers and 5 receivers so can handle the full RS232 handshaking lines.  I didn't check this out thoroughly, but belled out all 8 DB9 pins and all seem to connect to different pins on the SP213 so I'm guessing it's the full suite of handshaking lines is supported.  With a full set of lines, it should be possible to leech power for a level converter easily.  The data sheet for the SP213 is here:

http://silicon-verl.de/home/flo/projects/meridian/sp213.pdf

Of course, there's always a gotcha.  When I took a closer look at the insides I noticed traces of rust on the DB9 and USB connectors, so I guess it's been exposed to water at some point.  But not to worry too much, it works just fine.

The other advantage of it in my view, is that it's not FTDI.  In the past I've looked specifically for FTDI based chips but the bricking drivers from them have have made me nervous.  What a bad move!

Well that's about it so thanks for reading.....

Steve