RS232 Hack

[wd5gnr]

I have been thinking about wiring an RS232 port to the back with a switch so you could pick. But this morning a cheap hack occurred to me that takes care of my immediate needs.

If you look on eBay there are these little USB to TTL RS232 dongles that you can buy for like $5 or so from China. No handshaking but that's ok. I just wired the ground pin to the expansion connector and then the RXD pin to pin 22 of the expansion (ground is pin 20). Now I can get an "echo" of everything the processor sends to the screen on RS232. NOTE: the expansion connector is numbered like an IC not like a connector. So pin 20 is the furthest one down the row that pin 1 is on and the pin directly across from pin 1 is pin 40!

Not the best pictures but:
http://www.flickr.com/photos/wd5gnr/5229647484/

and:
http://www.flickr.com/photos/wd5gnr/5229647474/

Here's minicom showing a simple basic program plus the debugging (note my firmware is patched to show 3 bytes @PC at the end so your YMMV).
http://www.flickr.com/photos/wd5gnr/5229069641/

If any of that is unclear, ask.

[vbriel]

I just ordered one of these, would make a nice connection to a computer for those that don't want to use a monitor and keyboard. I thought about powering the Altair 8800micro off USB but the LED's draw too much for the USB port, I wouldn't want people pushing their USB ports and blowing them up.

[Toolkitman]

Can i buy this converter to make this hack? This is the link http://cgi.ebay.it/USB2-0-to-RS232-TTL-Converter-Module-PL2303-4pcs-cable-/270694777675?pt=LH_DefaultDomain_0&hash=item3f06aa834b#ht_3985wt_738

[Toolkitman]

Or this one? http://cgi.ebay.it/USB-to-RS232-TTL-Module-without-modem-signals-/280630170443?pt=BI_Electrical_Equipment_Tools&hash=item4156dc934b

[galaga]

yes both will work fine

[Toolkitman]

Thank you

[Toolkitman]

Hi,
i have connected the rs232 to usb interface to the Altair with gnd to pin 20 and rxd to pin 22, i have installed the right driver for windows but still cant get anything in hyperterminal. The rs232 led works when i power up the Altair 8800 micro. I think i need to know the setup for hyperterminal. Anyone can help?

[galaga]

i would use putty not windows hy/trem
i think its 9600, 8bits, 1stop , no flow control