Nokia 232, 239 服务手册
After Sales
Technical Documentation
Handsfree Desktop Charger CHH–7
Original, 11/94
Page 18
Circuit Description (DC3H)
The DC3H–Module consists of the following functional blocks:
– Supply Voltages
– Control Logic
– Battery Charging
– Spare Battery Discharging
– Watchdog Function
– Switch Mode Power Supply
– Microphone Amplifier and corresponding switches
– Speaker Amplifier and corresponding switches
Refer to Figures 4 and 5 for DC3H circuit diagrams (sheets 1 and 2).
Control Logic
Charging is controlled by processor D300. The D300 is a single–chip type
controller incorporating RAM, ROM, an A/D converter, and a multifunction
timer/counter. The processor communicates with the phone via the
M2BUS. The M2BUS interface comprises transistors V200, V201 and
corresponding resistors.
controller incorporating RAM, ROM, an A/D converter, and a multifunction
timer/counter. The processor communicates with the phone via the
M2BUS. The M2BUS interface comprises transistors V200, V201 and
corresponding resistors.
Table 23. Port A Signals of the Processor:
PORT A
NOTES
PA0: PHONE GREEN
(output)
Phone LED control, green: ”1”
PA1: PHONE RED
(output)
Phone LED control, red: ”1”
PA2: SPARE GREEN
(output)
Spare battery LED control, green: ”1”
PA3: SPARE RED
(output)
Spare battery LED control, red: ”1”
PA4: DISCHARGE BUTTON
(input)
Discharge button control,
”0”: start / stop discharge
PA5: SPARE DISCHARGE
(output)
Discharge spare battery,
”1”: discharge enabled
PA6: Unused
(output)
Not Used
PA7: CHARGER
(output)
Charger Switch, ”1”: charger on