Evaluation Kit User Manual for PIC Board

EV6000

© 1996 Consumer Microcircuits Limited

14

UM6000/3

_rxd

PORT C

bit 1

_lvcp

PORT C

bit 2

( _txd

for EV6040)

_muten

PORT C

bit 3

( _rxeq for EV6040)

If the user wished to manually enable the near end speech path (from TP18 to the line), the following

commands would be entered:

>ok

f!<Return>

>05 08<Return>

; sets HI port A bit 3, energising relay 1

>07 08<Return>

; sets HI port C bit 3, enables speech input (TP18)

><Esc>

>ok

1.6.2.3 Applications Software

(a)

Application/Demonstration Commands

(Press <Esc> to exit these functions)

cas

Follows the CAS detection part of the CIDCW algorithm detailed in the FX602 data

sheet. Near end speech is input between TP18 and VSS (TP1 or TP2 ). If the detect

output is set for a time longer than T1, the near end speech path (TP18 to the line) is

muted. If the detect output then remains set (making a total detect time longer than T3

but less than 65ms) then, after a quiet period of 50ms, the DTMF digit "D"

acknowledgement tone is transmitted down the line.

Once this sequence has been completed, or aborted for not meeting a timing

requirement, the near end speech path is un-muted and the FX602 returned to tone

alert mode.

On the EV6020 board, the line termination resistor R20 (

≈ 600Ω) should be fitted.

Note that this software does not present an off hook dc load to the line.

casd

Operates as above, but two decimal counters are run. The first counts the number of

times the near end speech is muted and the second counts the number of times the

DTMF acknowledgement is sent. The results are displayed and updated in the form:

M=00000000,A=00000000.>

where M represents mutes of the near end speech path and A represents

acknowledgement tones sent.

On the EV6020 board, the line termination resistor R20 (

≈ 600Ω) should be fitted.

Note that this software does not present an off hook dc load to the line.

cast

This enables the user to adjust the CAS detection algorithm timings T1 and T3. The

user is prompted as follows:

T1=3A98>

Type <Return> for no change, or enter the new setting (in

µs) in hex.

e.g.

For T1 = 10ms = 10,000

µs = 2710hex, type 2710<Return>

The user is then prompted to alter T3 in the same way. The default settings are T1 =

15ms = 3A98hex and T3 = 25ms = 61A8hex.