CDC3205G-C Micronas, CDC3205G-C Datasheet - Page 202

• Manufacturer Part Number: CDC3205G-C
• Description: Automotive Controller Family The Device is a Microcontroller For Use in Automotive Applications.the On-chip Cpu is an Arm Processor ARM7TDMI with 32-bit Data And Address Bus, Which Supports Thumb format Instructions.
• Manufacturer: Micronas

CDC 32xxG-C
30.1. Functional Description
The Audio Module output frequency is defined by the follow-
ing formulas:
Frequency:
Amplitude:
where the maximum amplitude is 1 if AMAS is equal to or
bigger than AMPRE. In the latter case the amplitude remains
constant until the decay mechanism has decreased AMAS
below AMPRE.
Duration:
AMF, AMPRE, AMAS and GDF are register values and
described later.
The initial gong sound amplitude is set by writing the Audio
Module Amplitude & Status Register (AMAS), this write also
starts the gong sound. An active audio module is indicated
by the read only Audio Module Active Bit (AMA) in the AMAS.
Fig. 30–2:
30.1.1. Hardware Settings
The AM clock frequency F
30.1.2. Initialization
Prior to entering active mode, proper SW initialization of the
Ports has to be made. The ports have to be configured Spe-
cial Out. Refer to “Ports” for details.
Three Audio Module Registers have to be set before the
gong sound can be started: the gong prescaler (AMPRE),
the gong sound frequency (AMF) and the gong duration fac-
tor (AMDEC.GDF) register.
200
The sound is generated by
blocks of pulses
F Gong
=
One block of pulses
Sound generation
F AMTrigger
-------------------------------- -
2 AMF
Ampl.
+
1
----------------------------------
AMClock
AMPRE
=
AMAS
----------------------------------------------------------------- -
2 AMF
is set by HW option AC.
+
+
1
F AMClock
+
1
1
AMPRE
+
June 12, 2003; 6251-579-1PD
2 x AMF x AMPRE -> F
1
AMPRE
AMAS
(PWM)
Every 1st..32nd cycle of the gong sound frequency (depend-
ing on the Gong Duration Factor (AMDEC.GDF)) a new
amplitude value is calculated (F
the amplitude decrement frequency F
output of the adder into the amplitude latch (13 Bit) and
simultaneously the 8 MSBs into the PWM.
During the first low cycle of F
ment
lated amplitude, but takes effect at the output not until the
next high cycle of F
put to generate the gong sound frequency, while the
decreasing PWM-value generates an exponential decreasing
amplitude.
As soon as the 8 MSBs of the amplitude latch are reaching
zero, the AMA will be reset, which deactivates the audio
module.
For the effect of CPU clock modes on the operation of this
module refer to section “CPU and Clock System” (see
Table 4–1 on page 37).
30.1.3. Start Gong
The gong sound is started by writing the initial amplitude
value into AMAS. Simultaneously with the write to AMAS the
Flag Audio Module Active (AMA) is set, which enables the
F
30.1.4. Restart Gong
It’s possible to restart the gong sound simply by writing a
new initial amplitude value to AMAS independent of the
former initial value or the current value of the register. (Note:
AMClock
edge the PWM is already running with the newly calcu-
Gong
-input.
t d
AMF x AMPRE
----------------------------------------- -
ln
Gong
0,5
ln
. F
–
1
PRELIMINARY DATA SHEET
ln
Gong
–
Gong
AMAS
----- -
32
1
Decrement
is modulating the PWM-out-
following the active F
Decrement
---------------- -
F Gong
2
). The falling edge of
GDF
is latching the
Micronas
Decre-