Others - Panasonic BB-HCM547A Service Manual

4.9.

Others

[I/O Terminal]
• The Input terminal has two systems; both of them are connected to the Input Port of the IC101 GPIO.
• Due to Internal Pull-up Resistance, the PNP Transistor (Q532, Q533) on the following level is usually in the OFF state and the
Input Port connected to the collector is at L level.
• If the terminal is short-circuited with the GND or the signal of L level is input, the PNP Transistor goes ON and the Input Port
goes to H level.
• The CPU checks the state of this port regularly to detect a change in this signal.
• The Output terminal is controlled by the Output Port of the IC101. When the Port output is L, the transistor (Q534) on the follow-
ing level is OFF and, when the output is H, the transistor is ON. This transistor has open collector output and it controls external
equipment via external pull-up.
[RESET SW (SW103)]
• The RESET SW (SW103) mounted on the Main board is connected to the output of the RESET IC (IC106). It is usually at H level
and goes to L level, when the SW is pressed. It becomes the same movements as the hardware reset.
[CLEAR SETTING SW (SW101)]
• The Clear Setting SW (SW101) mounted on the Main board is connected to the Input Port of the GPIO. It is usually at H level and
goes to L level, when the SW is pressed.
• The CPU(IC101) monitors this Input Port periodically and, if it detects that this SW is pressed longer than a specified period, the
setting values other than the RTC are returned to factory settings.
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BB-HCM547A