macintosh serial port connections

Archiver · 2000-09-14 12:45

hello all:

i would like to use my BS2 connected to my mac for communication
during runtime (i.e. not for programming -- i've read the pdf at the
parallax site, etc. about using virtual pc).

however, i can't seem to find the pin diagram for the mac's serial
port and for diagrams i find that *might* be right, i'm not sure
whether DTR would be connected to ATR or would it be DCD, etc. etc.

so, i'm sure someone must have figured this and i would be ever so
grateful if someone could fill in the blanks for me:

mac mini-din female pin number to basic stamps pin
? sout
? sin
? atn
? gnd

also, on the pc diagram provided by parallax, pins 6 and 7 (DSR and
RTS) are connected. is this necessary for the mac?

thanks so much for any light you can shed on this matter.....

chund

Archiver · 2000-09-14 14:12

Disclaimer: I know nothing (and I mean nothing) about the Mac.

However here is some info from (http://csgrad.cs.vt.edu/~tjohnson/pinouts/):
mac serial port:
(printer end)
Connector: mini-circular-square-din-type connector

U
8 7 6
5 4 3
2 1

1 handshake out (DTR?)
2 handshake in (RTS?)
3 TD-
4 GND
5 RD-
6 TD+
7 GPinput (NC on Mac plus and earlier)
8 RD+

This is an RS-422 interface not RS-232, hence the paired IO pins (+ and -).
To connect to an RS-232 device: attach the - pins to the RS-232 data
pins, and RD+ to ground. The handshake in and out are the hardware flow
control, GPinput is carrier detect.

So you'd need a converter.

Here is another pinout from
(http://www.hut.fi/Misc/Electronics/docs/lan/mac_serial.html)

Macintosh (DTE) Modem (DCE)
DIN-8 DB-25

Pin Signal Signal Pin

3 TxD-

TxD 2

4 GND ----+

GND 7
8 RxD+ ----'

5 RxD-

RxD 3
6 TxD+ (nc)

/

###

###

/
###

However, I have also heard this:
The serial ports use the EIA422 standard which is a 'differential' system
using 5 volt outputs. It is possible for the Mac to accept 'single ended'
RS232 data (on pin 5) by grounding pin 8 at the Mac end. You can usually
send 5 volt data (from pin 3 on the Mac) to a RS232 input but the noise
immunity will be reduced.

That corresponds with the pinout above.

So to summarize, ground pin 8, RX on pin 5 and transmit on pin 3.

Hope that helps.

Regards,

Al Williams
AWC
* Floating point math for the Stamp, PIC, SX or any microcontroller:
http://www.al-williams.com/awce/pak1.htm

Archiver · 2000-09-15 10:37

go there: http://www.43south.co.nz/stamps/ and you will find the information
you want.

> i would like to use my BS2 connected to my mac for communication
> during runtime (i.e. not for programming -- i've read the pdf at the
> parallax site, etc. about using virtual pc).
>
> however, i can't seem to find the pin diagram for the mac's serial
> port and for diagrams i find that *might* be right, i'm not sure
> whether DTR would be connected to ATR or would it be DCD, etc. etc.
>
> so, i'm sure someone must have figured this and i would be ever so
> grateful if someone could fill in the blanks for me:
>
> mac mini-din female pin number to basic stamps pin
> ? sout
> ? sin
> ? atn
> ? gnd
>

Archiver · 2000-09-19 02:05

> From: "Al Williams" <alw@a...>
> Subject:
>
> Disclaimer: I know nothing (and I mean nothing) about the Mac.
>

> This is an RS-422 interface not RS-232, hence the paired IO pins (+
> and -). To connect to an RS-232 device: attach the - pins to the
> RS-232 data pins, and RD+ to ground. The handshake in and out are the
> hardware flow control, GPinput is carrier detect.
>
>
> So you'd need a converter.
>
They use the National DS8925(as does some of the Kodak digital
cameras) which is a TIA/EIA RS422 driver/receiver chip that runs +
and - 5V differental signal. The RX has a range of +8 to -8V

macintosh serial port connections

Comments