Configuration Bytes

Configuration Byte 1

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

0

0

ECLK

IOM

ENC1

EOD1

CMP1

FB1

ECLK

Channels 1 & 2

1 = External codec clock; 0 = Internal codec clock

IOM

Channels 1 & 2

1 = Binary input/output; 0 = 2-of-6 input/output

ENC1

Channel 1

1 = Enable channel; 0 = Disable channel

EOD1

Channel 1

1 = Indicate end of digit; 0 = No end of digit indication

CMP1

Channel 1

1 = Automatic Compelled mode; 0 = Manual mode

FB1

Channel 1

1 = Forward mode (Tx forward frequencies and Rx backward frequencies)

0 = Backward mode (Tx backward frequencies and Rx forward frequencies)

Configuration Byte 2

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

0

1

0

0

ENC2

EOD2

CMP2

FB2

ENC2

Channel 2

1 = Enable channel; 0 = Disable channel

EOD2

Channel 2

1 = Indicate end of digit; 0 = No end of digit indication

CMP2

Channel 2

1 = Automatic Compelled mode; 0 = Manual mode

FB2

Channel 2

1 = Forward mode (Tx forward frequencies and Rx backward frequencies)

0 = Backward mode(Tx backward frequencies and Rx forward frequencies)

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2

M-986-2R2

Rev. 3

Function Description

The M-986 can be set up for various operating modes

by writing two configuration bytes to the coprocessor

port.

Configuration Options

External/Internal Codec Clock (ECLK): If external

codec clocking is selected, an external clocking source

provides an 8kHz transmit framing clock and an 8kHz

receive framing clock. It also provides a serial bit clock

with a frequency that is a multiple of 8 kHz between

2.496 MHz and 216 kHz for exchange of data via the

serial ports. When internal codec clocking is selected,

the M-986 provides an 8kHz framing clock and a 2.048

MHz serial bit clock.

Binary/2 of 6 Input/Output (IOM): When the 2-of-6

input/output is selected, the M-986 encodes the

received R2 MF tone pair into in a 6-bit format, where

each bit represents one of the six possible frequencies.

A logic high level indicates the presence of a frequen-

cy. The digital input to the M-986 that selects the trans-

mitted R2 MF tone pair must also be coded in the

2-of-6 format.

When binary input/output is selected, the M-986

encodes the received R2 MF tone pair into a 4 bit bina-

ry format. The digital input to the M-986 that selects the

transmitted R2 MF tone pair must also be coded in a 4

bit binary format.

Enable/Disable Channel (ENC): When a channel is

disabled, the receiver does not process its codec input

for R2 MF tones, and the transmitter does not respond

to transmit commands. If a transmit command is given

while the channel is enabled, the “tone off” command

must be given before the channel is disabled.

Disabling the channel does not automatically shut off

the transmitter. When a channel is enabled, the receiv-

er and transmitter for that channel function normally.

End-of-Digit Indication (EOD): The end-of-digit indica-

tion option configures the M-986 to inform the host

processor when the far end terminates transmission of

the R2 MF tone it is sending. If this option is disabled,

the host processor will not be notified when tone

transmission terminates.

Automatic Compelled/Manual Sequence Signaling

(CMP): When manual mode is selected, R2 MF tone

transmission is turned on and off only via command

from the host processor.

If the automatic mode is selected, the transmitter and

receiver perform the compelled signaling handshake

automatically. The specifics of operation are different

for the forward and backward configurations.

In forward mode, the transceiver can exist in two

states, STATE 1 and STATE 2:

Transmitter under control of the host.

Transmitter off unconditionally.