Advices For Connecting External Circuits To Ports; Special Digital Ports; Start And Reset; Freq1 Und Freq2 - Conrad Electronic C- CONTROL 1 UNIT M 2.0 Hardware Manual

Advices for connecting external circuits to ports

Outputs – HI level:
The total output current of all ports has to be limited to less than 20mA if the Unit M 2.0 is
supplied with 12V operating voltage (at the dedicated 12V terminal )
The total output current of all ports has to be limited to less than 20mA if the Unit M 2.0 is
supplied with 5V operating voltage (at the dedicated 5V terminal )
If external voltages >5V are applied to output the ports, a current into the output ports occures.
This is permitted only if the current is limited to less than 1mA by a resistor.
Outputs - LO level:
A LO level output can be considered to be a short from the voltage source to GND. The current
flow to GND must be limited to less than 10mA (e.g. by a resistor).
Inputs:
If external voltages >5V are applied to the input ports, a current into the input ports occures.
This is permitted only if the current is limited to less than 1mA (e.g. by a resistor).
Disregarding this rules will immediatele result in permanent damage of ports or the
C-Control Unit itself and connected devices

Special digital ports

All special digital ports of the unit are connected to pull up resistors as far as they are inputs.

Start and Reset

This ports may be connected to push buttons if a manual start or stop of user programs is required.
Push the START button to run a BASIC program, downloaded previously to the unit's memory. Press
RESET to stop a running program and entering the download mode.
To ensure proper function, the AUTOSTART jumper at the unit must be removed.
JP2 at Unit M2.0
JP9 at Unit M1.2

FREQ1 und FREQ2

This ports are always and exclusivly inputs. The primary operation is frequency counting in the range
from 0 to 32kHz. FREQ 1 supports the feature to synchronize the system clock if a DCF77 receiver
module is connected to this port. The synchronization is done automatically in the background, i.e. no
user action is required. The receiver module must provide a open collector output to switch this port lo.
Use shielded cables to connect the receiver module to the unit.

IRQ

The IRQ port is alwas input and serves the immediate reaction on an external request i.e the current
operation is interrupted an the external event is serviced by a appropriate Interrupt Routine. The IRQ
input is negative edge triggered.

Beep

The BEEP port is always an output an usually connected to a piezo buzzer. He serves for program or
alert status indications during normal program operation. During debugging your program this buzzer
may be useful also. The audio frequency ranges from 10kHz to 100Hz.

.RXD/TXD

The serial interface (RXD=input TXD=output) is designed for 5V digital logic level, You never must
connect a RS232 interface directly to this ports. This would immediately result in permanent damage
to the C-Control computer