Re: [OT] sparc-->mac serial cable
On Tue, Jan 28, 2003 at 10:48:01PM +0000, Hugh Saunders wrote:
> On Tue, Jan 28, 2003 at 09:05:18PM +0100, Frank Gevaerts wrote:
> > On Tue, Jan 28, 2003 at 06:12:10PM +0000, Hugh Saunders wrote:
> > > Hello, i am attempting to build a serial cable so i can use an old mac
> > > laptop [powerbook510] to boot a sun sparc ipc and start it network booting.
> > > Google reveals the following pinouts:
> > >
> > > AppleMac [1]
> > > DIN8 Signal Description
> > > Pin
> > > ----------------------------------
> > > 1 RTS Handshake output
> > > 2 CTS Handshake input
> > > 3 TXD- Transmit data (inverted)
> > > 4 SG GND
> > > 5 RXD- Receive data (inverted)
> > > 6 TXD+ Transmit data
> > > 7 DCD General Purpose Input
> > > 8 RXD+ Receive data
> > >
> > > Sparc IPC [2]
> > > DIN8 Signal Description
> > > Pin
> > > ----------------------------------
> > > 1 DTR Data Terminal Ready
> > > 2 CTS Clear to Send
> > > 3 TXD Transmit Data
> > > 4 GND Ground
> > > 5 RXD Receive Data
> > > 6 RTS Request to Send
> > > 7 DCD Data Carrier Detect
> > > 8 RTXC Receive Clock
> > >
> > > My first question is: how do i wire it? do i try and match the pins up ie
> > > RTS-->RTS or do i cross over as in RTS-->CTS?
> > >
> > > Next question, whats with TXD[+-] on the mac but only TXD on the sparc? can
> > > i just use TXD+ -->TXD? [or TXD+ -->RXD if crossed over] then ignore
> > > TXD-?
> >
> > I would wire TX+->RX, RX+->TX, and GND->GND, and leave the rest
> > unconnected at first, and if you really need hardware handshaking,
> > RTS<->CTS and CTS<->RTS.
> Thanks, i understand up to here...
>
> > IIRC some systems also need DTR and /or DCD to
> > be wired high
> wired high?
connected to the voltage that represents a logical 1 on the interface
concerned.
> will try with just the three you suggest for now...
Watch out! Check the specs first. IIRC a Mac uses an RS-422 interface
with 5V levels, whereas RS-232 uses 12V levels. Sometimes an RS-232
input will work OK when fed 5V signals, but going the other way,
there's a risk of overloading the RS-422 input.
You need a level converter, which is dead easy to make, but perhaps
you're not comfortable with doing stuff like that... I'd be really
surprised if you couldn't buy them, so have a look on Google for
something like rs232 rs422 "level converter".
Pigeon
Reply to: