RCH
INSTALLATION AND MAINTENANCE MANUAL model TOUCH ME
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9.9 RESET AND POWER FAILURE CIRCUITS
The reset and power failure circuits allow to control the microprocessor’s Power Supply voltage,
and allow to intervene when turning the system on and off.
During system startup, the power failure circuit disenables the /DCFAIL signal when the input
voltage (VI) is sufficient for system operation. Simultaneously, the circuit in charge of checking the
Power Supply voltage of the system’s logical unit (VCC +5V), allows the microprocessor to start
operation (/RES) when Power Supply v5V becomes stable at 5V.
During system shutdown, the power failure circuit warns the microprocessor of the missing input
voltage in advance with respect to the signal /RES which would intervene to block microprocessor
as well as SRAM and MMC memories operation.
9.10 BUZZER CIRCUIT
The command circuit for the Error signal buzzer, for support when striking
keys and in the
visualization of some messages, is controlled by the microprocessor through the BUZ port
by means of the Q1 transistor, which grounds the negative terminal of the BZ1 buzzer
transducer.