CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (Telephone Function)

(3)Interrupt

The dialing, pause and flash functions generate an interrupt when their operation has finished. At this time, the interrupt factor flag ID (FFF9H•D0) is set to "1". An interrupt request to the CPU will be generated when the interrupt mask register EID (FFE9H•D0) is set to "1" and will be masked when EID is set to "0". However, the interrupt factor flag ID will be set to "1" when the above function has completed even if the interrupt is masked. The end of operations can also be checked by scanning the ID flag. The ID flag is reset to "0" by writing "1". The ID flag must be cleared to "0" before starting the next interrupt.

Figure 4.14.3.2 shows an example of dialing pulse transmission procedure.

1. Setting

 

START

 

 

 

 

Write "1000"

 

 

to FF10H

 

 

 

 

 

 

 

Write

"0110"

 

 

to IDP

 

 

 

 

 

 

 

Write

"0111"

 

 

to FTS

 

 

 

 

 

 

 

Write

"0010"

 

 

to PTS

2. Executing

 

 

 

 

 

Set

 

 

HSON = 1

 

 

 

 

 

 

 

Set

"5"

 

 

to TCD

3. Interrupt

 

 

 

 

 

 

 

 

 

No

Interrupt

 

 

 

 

 

 

Yes

 

 

 

 

 

 

Reset ID

 

 

 

 

 

Select • Pulse mode

•Make ratio = 40 : 60

•Dialing rate = 10 pps

Inter-digit pause time = 563 ms

Flash time = 656 ms

Pause time = 2 sec

Off-hook

Dial number "5"

Reset interrupt factor flag ID to "0" for next operation

Fig. 4.14.3.2 Flow chart of dialing pulse transmission

In the setting step, "1000B" is written to address FF10H to set pulse (DP) mode, the make ratio = 40:60 and the dialing rate = 10 pps. Then data is written to IDP (FF15H), PTS (FF11H) and FTS (FF12H) to set an inter-digit pause time, pause time and flash time. These settings are not necessary when using the initial set values of IDP, PTS and FTS.

In the executing step, "1" is written to HSON (FF18H•D3) to set off-hook. This makes the DP terminal go to a High (VDD) level and connects the telephone line. Then "0101B" (dialling number = 5) is written to TCD (FF17H) to start the dialing operation. The DP terminal outputs 5 pulses according to the condition set. At the same time, the XTMUTE and XRMUTE signals become active (if the R10 and R11 terminals have been set as those signal output ports). In the actual application, this step should include the processing for fetching the hook switch status and for push button inputs.

When a series of pulses has been transmitted, an interrupt occurs. The next digit process can be started after resetting (writing "1" to) the interrupt factor flag ID.

S1C63558 TECHNICAL MANUAL

EPSON

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