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and

f2 = CR9 / 0.128 Hz

where CR8 and CR9 are decimal equivalents of the binary values of the CR8 and CR9 registers respectively.

Thus, any frequency between 7.8 Hz and 1992 Hz may be selected in 7.8 Hz step.

If "halved frequency tone range"is selected, Tone or Ring signal frequency value is defined by the formula:

f1 = CR8 / 0.256 Hz

and

f2 = CR9 / 0.256 Hz

This any frequency between 3.9Hz and 996Hz may be selected in 3.9Hz step.

If "doubled frequency tone range"is selected, Tone or Ring signal frequency value is defined by the formula:

f1 = CR8 / 0.064 Hz

and

f2 = CR9 / 0.064 Hz

Thus any frequency between 15.6Hz and 3984Hz may be selected in 15.6Hz step.

TABLE 12 gives examples for the main frequencies usual for Tone or Ring generation.

CONTROL REGISTER CR10

Remocon Function Enable

Bit REN(7) enables or disables the RemoconFunction. Default value is disabled.

Remocon Mode Selection

Bit RLM(6) is used to select between a transparent pressed button information and a latched pressed button

information at REMOUT. In both cases a debounce circuit (50ms max.) is active.

Remocon Output Inversion

Bit ROI(5) is used to invert or not the information at REMOUT. Default value is not inverted (i.e. pressed button

information is a logic 1 at REMOUT.

Remocon Detection Latch

Bit RDL(4) is set by the internal Remocon Function logic, after the debounce time, when a low level on REMIN

is detected. It can be reset by the mP writing CR10.

Preamplifier Gain Selection

Bit PG(3) provides the selection between 0dB and 20dB gain of the preamplifier. Default value is 20dB.

Microphone Bias Disabling/Enabling

Bit MB (2) enables or disables a switch for microphone biasing.

Default value is disabled.

Tone Frequency Range Selection

Bit DFT(1) and HFT(0) permits the selection among "standard frequency tone range" (i.e. from 7.8Hz to 1992Hz

in 7.8Hz step), "halved frequency tone range" (i.e. from 3.9Hz to 996Hz in 3.9Hz step), and "doubled frequency