Evaluation Kit for CMX838 Family Radio Processor
20
EV8380 User Manual
4. Write the following values to the SUBAUDIO TASK DATA ($95) register.
a. $81 (to enable tone detector 1 (67.0 Hz)) value = 0x80 | 0x01, then wait 50µs minimum
b. $87 (to enable tone detector 7 (82.5 Hz)), then wait 50µs minimum
c. $8A (to enable tone detector 10 (91.5 Hz)), then wait 50µs minimum
d. $8C (to enable tone detector 12 (97.4 Hz), then wait 50µs minimum
e. $92 (to enable tone detector 18 (118.8 Hz)), then wait 50µs minimum
f.
$94 (to enable tone detector 20 (127.3 Hz)), then wait 50µs minimum
5. Write $40 to SUBAUDIO PROCESSOR GENERAL CONTROL ($93) register.
a. This step includes power control, IRQ control, and the issuance of task 0 to place the device back
in normal running mode
5.2.6 How to Detect a User-Defined Subaudio Tone
Task 5 (program user-defined subaudio tone) effectively programs the center frequency of user
programmable detector 51.
To detect the presence of a user-defined subaudio tone, the user must first calculate the argument data
corresponding to the desired tone according to the following formulas:
96 511 f
§
¨
©
·
¸
¹
N = INT
100000
§
·
100000 N
96 f
¨
¸
¸
R = INT 0.5 + 511−
¨
©
¹
Argument = N 64 + R
The argument data for 65 Hz would be 31*64+14 = 1998 = $07CE.
The argument data is loaded into the argument data register, and task 5 is then issued to the tone signaling
processor.
The programmed center frequency can be back calculated by:
100000 N
f =
96(511− R)
In the above example, the actual center frequency would be 64.97 Hz.
NOTE: To determine the value to load in the SUBAUDIO PROCESSOR GENERAL CONTROL ($93) register,
the power control and IRQ control bits should be logically “OR-ed” with the desired task field.
For example, a C-BUS sequence to enable detection of a 65Hz tone (user-defined) would be:
1. Write $07CE to 16 BIT SUBAUDIO TASK DATA ($8E) register.
a. This is the required argument data for 65Hz tone.
2. Write $45 to SUBAUDIO PROCESSOR GENERAL CONTROL ($93) register.
a. Task 5 command (No IRQs enabled)
3. Wait 250µs
4. Write $3F to SUBAUDIO TASK DATA ($95) register.
a. Task 4 argument data to disable all decoders.
5. Write $44 to SUBAUDIO PROCESSOR GENERAL CONTROL ($93) register
a. Task 4 command (No IRQs enabled
6. Wait 250µs
7. Write $B3 to SUBAUDIO TASK DATA ($95) register.
a. Task 4 argument data to enable decoder 51 (The user-definable one)
8. Write $64 to SUBAUDIO PROCESSOR GENERAL CONTROL ($93) register.
a. Task 4 command (with IRQs enabled)
¤2001 MX-COM, Inc.
4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA
www.mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054
Doc. # 20480230.001
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