TouchLine station microprocessor, version 0161

Overwiew

General

The microprocessor is a Motorola 68HC05C4 mask programmed processor. It operates in different modes in stations with display and stations without display. The processor decides its operating mode by reading the pin PB0 after reset. If it is 0, the processor starts the display mode, if it is 1, the processor selects the non-display mode.

New features in the revised version 0159 are indicated by italics.

Display mode

In a station with display, the processor scans the keyboard every 10 ms and processes data received from the serial line. The processor is in the WAIT state between messages and scans to conserve power. The processor can scan up to 60 keys. The processor will signal the key by generating the digit tone and selecting the right ab loop current. All signalling is held for a minimum time even if the key is released to ensure that the exchange is able to receive it properly. In the display station, the M-key, C-key and Handset Off current levels are also controlled by the processor.

There is also options for scanning of a matrix keyboards, either in normal mode or in MICOM mode. M- and C-keys are then included in the scanned keyboard matrix.

The processor can output received data to a LCD display. It can also output data on the SPI port. The processor can set or reset an output line that is used to override handset off/volume setting. In addition, one extra output can be set or reset, alternatively set with timeout. This is primarily intended for door opening.

Non-display mode

In a station without display, the processor is in STOP condition when no key is pressed. The processor is started by a depressed key and continues to run until the last key is signalled to the exchange. The processor generates the digit tone and selects M-key current if necessary. The digit tone and current are held for a minimum time even if the key is released. In non-display mode, the processor can scan 40 keys.

There is also options for scanning of a matrix keyboards, either in normal mode or in MICOM mode. M- and C-keys are then included in the scanned keyboard matrix.

Pin usage

Display mode

The pins are used as follows:

Pin Name	Description
RESET	This is the reset input, the watchdog is connected to this input.
OSC1,<br\>OSC2	A 2.45MHz ceramic resonator is connected to these two pins. <br\>
VCC	The pin is connected to +5V.
GND	The pin is connected to 0V.
IRQ	The pin is not used and should be connected to +5V.
PA0..PA7	This 8 bit port is used as bi-directional data bus with the display. It is also used as address bus when data is shifted out on the SPI output.
PB0	At start-up, this input should read 0 to indicate that the processor should start display mode. Afterwards, it is used as E signal for the display.
PB1	R/W* signal for the display.
PB2	A0 signal for the display.
PB3	Common line for all digit only keys. The output is taken low when digit only keys are scanned. In matrix keyboard mode, this is row address 3.
PB4<br\><br\><br\>	Common line for digit + current keys. The output is taken low when digit + current keys are scanned. When data has been shifted out on the SPI, it is latched by taking both PB3 and PB4 low. Since PB3 and PB4 may be shorted together if more than one key is pressed, PB3 and PB4 should be buffered in circuits using the SPI output. In matrix keyboard mode, this is row address 2.
PB5	Handset and volume override. This output may be set to 1 or 0 by a command from the exchange. It is normally used to override handset off and volume control.
PB6	Handset off input. 5V at input indicates handset off.
PB7	ID control. Set to 1 while a digit is being sent.
PC0	Key no. 8 input. Used as output to latch data into external shift registers when scanning keys. If 0V at reset, matrix keyboard mode is selected.
PC1	Key no. 9 input. In matrix keyboard mode, this is an output, row address 1.
PC2	OPEN/PRIVATE switch input. 5v at input means OPEN.
PC3	M-key input. 0V at input means key pressed. In matrix keyboard mode, MICOM mode is selected if 0V at reset.
PC4	C-key input. 0V at input means key pressed. In matrix keyboard mode, this is an output, row address 4.
PC5	Handset current control. Taken low when either handset is off or handset off current is used together with digit.
PC6	M-key current control. Set high when either M-key is pressed or m-key current is used with digit.
PC7	C-key current control. Set high when either C-key is pressed or as a speed-up for m-key current.
PD0/RDI	Serial data input from exchange. 9600 baud, 8 bit data, 2 bit stop, no parity.
PD1/TDO	Serial data output. Data from the exchange may be transmitted here. 9600 baud, 8 bit data, 2 bit stop, no parity. This pin can also be used as an output pin controlled by commands 0x26, 0x27,0x28, and 0x29
PD2/MISO	Synchronous data input used to read key scan from external shift register.
PD3/MOSI	Synchronous data output. Data from the exchange may be shifted out on this output. After shifting, data is latched into external registers by taking both PB3 and PB4 low. The address is available on PA0..PA7 while strobing.
PD4/SCK	Clock output for synchronous input/output. Can be used to toggle watchdog.
PD5/SS*	Must be tied to 5V.
PD7	cd-loop polarity sense input. 5V at input signals c-wire negative.
TCAP	Not used, should be tied to 0 or 5V.
TCMP	OPEN/PRIVATE current control and digit tone output. Square wave output of digit tone when sending digit, else 1 when in PRIVATE and 0 in OPEN.