Remote Processing RPC-220 - Manual (Page 22)

SERIAL PORTS SECTION 4
Page 4-2
POWER CONTROL
The RS -232 driv er chip U 9 has a shut dow n control to
reduce power (about 10 m a). This line is controlled by
CPU port P4.2. Examples are in RTC-3.C in the RTC
directory.
On power up or reset, the control line automatically goes
high, enabling RS-232. You can save about 10 ma.
current by bringing P4.2 low.
Allow about 1 ms recovery time for U9 before
transmitting characters when P4. 2 is brought back high
(from IDL E mode).
I 2 C BUS
The I 2 C bus uses two wires SDA (available at J3-17) and
SCL (available at J3-15) to transfer information between
devices connected to the bus. Refer to the
8X552OV. PDF data sheet for more progr amming
information. D etailed information starts on page 3-481.
This bus use s ports P 1.6 and P1. 7 which ar e shared with
the LC D display p ort.
SERIAL PORT PIN OUT
Pin out for J4 is shown below. U nused pins are open.
You can easily make your own cable from 10 pin header
and female DB-9 IDC connectors to a PC. Take a 9
wire ribbon cable and align pin 1 to pin 1 on each
connector and crimp.
J4 pin N a m e Direction DB-9
from card pin
3 Tx 0 Out 2
4 RTS (Rx 1) In 7 (3)
5 Rx 0 In 3
6 CTS (Tx 1) Out 8 (2)
9 Ground 5
10 + 5
Alternate functions and pin out for RTS and CTS are
shown above in parentheses. W hen used as transmit and
receive, these lines must be broken from the cable and
wired directly to a connector.
The corresponding signal names from the DB-9 are the
opposite of what is coming out of the R PC-220 . T hus,
Tx becomes Rx on the PC . C TS becomes RT S on the
P C .
Rx1 and Tx 1 a re alternate uses for RTS and C TS lines.
These are the CO M1 software ser ial port lines. The
VTC -29F serial cable connects to the RPC-220 and
breaks out C OM0 and COM 1 into two connectors.
APPLICATION PROGRAMS
The following program s are in the SERIAL dire ctory.
F i le n am e Description
SOFT .asm Uses software serial port. Baud rates from
300 to 9600. Should not be us ed with
interrupts.
C O M 00 . C Interrupt driven COM 0 serial routine.
Transmit and receive ar e buffered.