C120S Technical Manual TSP093.doc Issue 1.2 – January 2005
Money Controls 2005. All rights reserved.
Page 7 of 15
Ready signal
The Ready Signal is bi-directional. It is used to indicate to the Host controller that there is a
message waiting from the C120S. The C120S will stay powered up until the Host controller
polls and acknowledges the message or a time out occurs. It is also used to wake up the
C120S when the Host controller wishes to send a message to the coin mech.
Inhibit signal
Inhibit all can be used to slow down coin acceptance 'on the fly' giving the Host controller
time to deal with the preceding coin. The inhibit line status is read immediately prior to
operation of the accept gate solenoid. The decision to accept a true coin is made at this
point. A subsequent change in the inhibit line has no effect on the coin just accepted, which
will continue through the defined accept process. Following coins detected by the C120S
while the inhibit status is active will be rejected.
Signal Logic Levels
The logic levels between the C120S and the payphone controller is standard CMOS level,
that is Logic 0 shall be less than 30% of +5V (supply) and Logic 1 shall be greater than 70%
of +5V (supply).
The INHIBIT line is pulled up to +5V (supply) via a 1M-ohm resistor. The READY and
RESET lines are pulled up to +5V (supply) via 100k-ohm resistors. The DATA line is pulled
up to +5V (supply) via a 68k-ohm resistor.
3.2. 'Reset' timing & process
Reset is an active low signal which forces the processor into a reset state for as long as the
reset line is active. Minimum pulse width is 10ms.
Applying power to the coin acceptor triggers an internal power-on-reset (POR) condition
which provides the necessary reset timing without the need for any external signal
conditions. Note that for the POR circuit to function correctly, reset must be connected to the
supply voltage or left unconnected.
The reset line is diode protected and is internally pulled up to the +5V (supply) via a 100k-
ohm resistor.
Note that due to settling time required for the internal sensor oscillators to stabilise, the coin
acceptor requires a minimum period of 400ms to stabilise after the supply voltage has been
applied before it will accept coins.
