EV8380 Datasheet, PDF (14/29 Pages) CML Microcircuits – Family Radio Processor

Evaluation Kit for CMX838 Family Radio Processor
14
EV8380 User Manual
5) If the CMX838 is placed in its “Fast Initialization” mode, either directly or indirectly (through the
issuance of a “Soft Reset” task):
a. An initial delay of 250µs must be observed before the next task can be written to the SUBAUDIO
PROCESSOR GENERAL CONTROL ($93) register.
b. Once this initial 250µs delay has been observed, tasks can be issued to the device at a maximum
rate of one task per 50µs. Any “argument data” required for the next task may be loaded into the
argument register during this initial 250µs delay.
c. While in the “Fast Initialization” mode, for tasks other than “Soft Reset” or “Fast Initialization”,
ensure that the required argument registers are not updated for at least 50µs after the
corresponding task has been issued.
6) To determine the data byte that should be loaded into the SUBAUDIO PROCESSOR GENERAL
CONTROL ($93) register, the power control settings and the IRQ settings should be logically “OR-ed”
with the desired task field. The resulting byte should then be loaded into the SUBAUDIO
PROCESSOR GENERAL CONTROL ($93) register.
4.2.1 Power-Up Initialization Sequence for CMX838
The tone signaling processor of the CMX838 should be fully initialized after the chip is powered up. The first
time the tone signaling processor is enabled after power is applied to the CMX838, a byte should be written to
the SUBAUDIO PROCESSOR GENERAL CONTROL ($93) register with the ‘task field’ set to $F. This setting
will clear the configuration memory and place the tone signaling processor in a “Fast Initialization” mode.
When the CMX838 tone signaling processor is in this mode, the tone encoders and decoders do not run.
To resume normal operation, after all initialization is completed, a byte with the ‘task field’ set to $0 should be
written to the SUBAUDIO PROCESSOR GENERAL CONTROL ($93) register.
The following sequence should be utilized when applying power to the CMX838 (i.e. after turning on the
EV8380). This sequence only needs to be executed upon “cold” power-up. For example, issuance of a
‘General Reset’ command after power has been applied does not require the execution of this initialization
routine:
1) Apply power to the EV8380.
2) Issue ‘General Reset’ (single C-BUS write of $01).
3) Write $4F to the SUBAUDIO PROCESSOR GENERAL CONTROL ($93) register.
b) This applies a ‘soft reset’ to the subaudio section of the CMX838, clearing its configuration
memory.
4) Wait 250µs for the ‘Soft Reset’ task to complete.
5) At the end of the 250µs delay, the CTCSS processor will automatically be in the “Fast Initialization”
mode. The tone encoders and decoders do not run while in this special mode. Please review section
4.2.1 and the CMX838 data bulletin for more information on the “Fast Initialization” mode.
6) Configuration of the CMX838 tone signaling processor can now be performed as desired.
7) Once the configuration is complete, a task of $0 should be written to the SUBAUDIO
PROCESSOR GENERAL CONTROL ($93) register in order to resume normal operation.
The initialization procedure is now complete.
After these steps have been performed, other registers should be set as necessary to achieve desired
operation (i.e. audio path switching, gain levels, baseband clock generation, etc).
5 Programming Examples
5.1 Device Setup
The following sections provide specific instructions on how to program the CMX838 to perform some of its
functions but, in a typical application, the CMX838 will also require some “setup” instructions (i.e. Tx or Rx,
amplifier gains, powersave settings, etc.). Example transmit and receive setup sequences follow. (More
examples can be found in the example tab-delimited files provided on the EV8380 CD-ROM.) The actual
initialization may vary depending on the specific application.
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