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S1C63558 TECHNICAL MANUAL EPSON 129
CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (Telephone Function)
CHFO: R13 output selection register (FF13H•D3)
Selects the R13 terminal function.
When "1" is written: HFO output
When "0" is written: General-purpose DC output
Reading: Valid
When using the R13 terminal for the HFO output, write "1" to this register. Furthermore, fix the R13
register at "1" and the R13HIZ register at "0".
The HFO output is controlled by the HF register (FF14H•D3).
At initial reset, this register is set to "0".
OSCC: OSC3 oscillation control (FF00H•D2)
Controls the OSC3 oscillation.
When "1" is written: OSC3 oscillation ON
When "0" is written: OSC3 oscillation OFF
Reading: Valid
When it is necessary to activate the DTMF generator or to operate the CPU at high speed, set OSCC to "1".
At other times, set it to "0" to reduce current consumption. At initial reset, this register is set to "0".
TPS: Tone/Pulse mode selection (FF10H•D3)
Selects a dialing mode.
When "1" is written: Pulse mode
When "0" is written: Tone mode
Reading: Valid
When "1" is witten to the TPS register, pulse mode (outputs dial pulses) is selected. When "0" is written,
tone mode (outputs tone signals) is selected.
At initial reset, this register is set to "0".
MB: Make/Break ratio selection (FF10H•D1)
Selects a make ratio for pulse mode.
When "1" is written: 33.3 : 66.6
When "0" is written: 40.0 : 60.0
Reading: Valid
The make ratio (make : break) of the dialing pulses that are generated from the DP generator is set. When
"1" is written to the MB register, 33.3 : 66.6 is set. When "0" is written, 40.0 : 60.0 is set. The DP generator
produces the dialing pulses as "Make" (High) period is before "Break" (Low) period.
This selection is valid only for pulse mode.
At initial reset, this register is set to "0".
DRS: Dialing pulse rate selection (FF10H•D0)
Selects a dialing pulse rate for pulse mode.
When "1" is written: 20 pps (pulses per second)
When "0" is written: 10 pps (pulses per second)
Reading: Valid
The pulse rate (number of pulses per second) for the dialing pulses that are generated from the DP
generator is set. When "1" is written to the DRS register, 20 pps is set. When "0" is written, 10 pps is set.
This selection is valid only for pulse mode.
At initial reset, this register is set to "0".