Hi,

Thanks for the info (below), but ...

The target circuit needs TTL RS232, +5V/0V, and there isnt room for a max232 chip in the target circuit, to convert the rs232 back
into TTL levels.  It also needs a 5V power supply to power the target circuit.  Additionally, it needs our own 4-pin plug coming out
of the unit to connect to the target circuit.

Any more ideas?  It would be possible to build out own - anybody know of any USB -> RS232 TTL chipsets out there?

Cheers,
Shane.

> -----Original Message-----
> From: Bob Ammerman [mailto:RAMMERMAN@prodigy.net]
> Sent: Tuesday, 3 July 2001 1:55 p.m.
> To: shane@keyghost.com
> Subject: Re: USB<->RS232 TTL serial adaptor : USB in, 4 wires (+5V, GND,
> TTL TX/RX) out
>
>
> You are probably much better off buying a commercial USB to RS232 converter.
> I've bought a couple at $30 each.
>
> Bob Ammerman
> RAm Systems
> (contract development of high performance, high function, low-level
> software)

> -----Original Message-----
> From: pic microcontroller discussion list
> [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Shane Tolmie
> Sent: Tuesday, 3 July 2001 11:36 a.m.
> To: PICLIST@MITVMA.MIT.EDU
> Subject: USB<->RS232 TTL serial adaptor : USB in, 4 wires (+5V, GND, TTL
> TX/RX) out
>
>
> I wish to make a USB -> RS232 TTL serial adaptor.  It plugs into the USB port, and provides 4 wires out - +5V, GND, and TX/RX at
> 0V/5V TTL levels.  All I'm interested in is the hardware.
>
> The hardware will look very simple - a USB plug on one end, and a 4-pin plug on the other.
>
> In your experience, could you recommended an appropriate USB <-> serial chip?  Maybe something off the shelf?  The main
> thing is, it
> needs TTL RS232 out, and a +5V power supply as well, to power the target circuit.  90mA maximum load.  I dont mind programming in
> C++ to interface to it.
>
> I dont need a PIC16C765 - I wish to interface to a smaller product that uses a PIC12C672, via a PC computer, without having the
> adaptor built into the target circuit.
>
> Regards,
> Shane.
>
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