AD Converter Detection Circuit

Figure 2-18 shows a block diagram of the A-D converter detection circuit.

The CPU includes an 8-channel 8-bit A-D converter. Each detection terminal is used to detect signals which continually change, making the best use of the A-D converter.

Table 2-11. A-D Converter Port Functions

Port

Signal Name

Function

Operation

ANO

DV35

Detects the fluctuation (32 to 38

VDC) of the driver circuit voltage (VP3).

Determines when the voltage is abnormal (rings the buzzer).

AN 1

H.TMP

Detects head coil overheating (120"C).

Stops printing until the head coil temperature drops (the printhead moves to the home position and is cooled by the external fan).

AN2

F.TMP

Detects head cooling fan overheating.

Stops the fan until the fan temperature drops.

AN3

MTR TMP

Detects carriage motor overheating.

Stops the motor until the temperature drops.

AN4

P.WID

Converts the paper width detector output level.

Detects the paper width.

AN 5

DIPSW 3

Reads the DIP switch settings.

Reads the DIP switch settings when the printer is reset.

AN 6

DIPSW 2

AN 7

DIPSW 1

The settings of DIP switches 1 to 3 are read by switching the time-sharing circuit.

The CPU writes the data to the PB ports of the E05A 16GA gate array so that only the port connected to the DIP switch the CPU wants to read goes LOW. the PB ports of the E05A 16GA gate array are normally used to drive the lamps on the control panel (except when the printer is reset).

To read a certain DIP switch, the data which makes only the port connected to the DIP switch go LOW

is written to the E05A1 6GA.

Since the A-D terminal, the DIP switch, and port PB of IC3C (grounded) become a closed circuit, DIP switch reading is enabled. This read operation is performed eight times per DIP switch and three times per A-D terminal.

PRINTER MECHANISM

<SENSOR>

DRIVER BOARD -1

DRIVER BOARD -1

PRINTER MECHANISM

HEAD TEMP.

HEAD FAN TEMP.

CARRIAGE MOTOR TEMP.

PAPER WIDTH

E05A16GA

CONTROL PANEL . (LAMP)

CONTROL PANEL . (LAMP)

Figure 2-18. A-D Converter Detection Circuit

Figure 2-18. A-D Converter Detection Circuit

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