----- Original Message -----
From: Alan B. Pearce <A.B.Pearce@RL.AC.UK>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Thursday, November 09, 2000 4:06 AM
Subject: Re: [PIC]: PIC16F877 and 186 solenoids


> >A control byte is recognised by bit 6 being 1, and an address byte
> >is recognised by bit 6 being 0. Either byte is identified as being
> >sent by bit 7 toggling. (The PC does this in software, inverting bit 7
> >each time it writes anything out). Bit 7 is decoded by a simple gate
> >circuit to generate a /WR strobe pulse for the PIC PSP port. Thus
> >the PC can send either byte in just 1 I/O write (1.5us), and can turn
> >on any valve on any board with just 2 I/O writes (3us).
>
>
> This has the advantage that you could set the port up as a generic text
only
> printer, and print characters to the port as an initial "get you going"
scheme
> as you do not worry about the handshake lines on the port. I like it.

This will not work unless his device returns 'acks' to the PC.

Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
software)

>
> Later when you need the speed you can worry about bypassing the underlying
code
> and access the port direct.
>
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