Timer/ Event Counter
Timer/Event Counter Programming Model
MOTOROLA
DSP56367
13-5
13.3.1
PRESCALER COUNTER
The prescaler counter is a 21-bit counter that is decremented on the rising edge of the
prescaler input clock. The counter is enabled when at least one of the three timers is enabled
(i.e., one or more of the timer enable (TE) bits are set) and is using the prescaler output as its
source (i.e., one or more of the PCE bits are set).
13.3.2
TIMER PRESCALER LOAD REGISTER (TPLR)
The TPLR is a 24-bit read/write register that controls the prescaler divide factor (i.e., the
number that the prescaler counter will load and begin counting from) and the source for the
prescaler input clock. See Figure 13-4.
13.3.2.1
TPLR Prescaler Preload Value PL[20:0] Bits 20–0
These 21 bits contain the prescaler preload value. This value is loaded into the prescaler
counter when the counter value reaches zero or the counter switches state from disabled to
enabled.
If PL[20:0] = N, then the prescaler counts N + 1 source clock cycles before generating a
prescaler clock pulse. Therefore, the prescaler divide factor = (preload value) + 1.
The PL[20:0] bits are cleared by the hardware RESET signal or the software RESET
instruction.
13.3.2.2
TPLR Prescaler Source PS[1:0] Bits 22-21
The two prescaler source (PS) bits control the source of the prescaler clock. Table 13-1
summarizes PS bit functionality. The prescaler’s use of the TIO0 signal is not affected by the
TCSR settings of timer 0.
If the prescaler source clock is external, the prescaler counter is incremented by signal
transitions on the TIO0 signal. The external clock is internally synchronized to the internal
clock. The external clock frequency must be lower than the DSP56367 internal operating
frequency divided by 4 (CLK/4).
23
22
21
20
19
18
17
16
15
14
13
12
PS1
PS0
PL20
PL19
PL18
PL17
PL16
PL15
PL14
PL13
PL12
11
10
9
8
7
6
5
4
3
2
1
0
PL11
PL10
PL9
PL8
PL7
PL6
PL5
PL4
PL3
PL2
PL1
PL0
— reserved, read as 0, should be written with 0 for future compatibility
Figure 13-4 Timer Prescaler Load Register (TPLR)
Summary of Contents for DSP56367
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Page 22: ...xxii MOTOROLA List of Figures Figure Number Title Page Number ...
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Page 148: ...4 6 DSP56367 MOTOROLA Design Considerations PLL Performance Issues ...
Page 248: ...9 30 DSP56367 MOTOROLA Serial Host Interface SHI Programming Considerations ...
Page 306: ...10 58 DSP56367 MOTOROLA Enhanced Serial Audio Interface ESAI ESAI Initialization Examples ...
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Page 390: ...A 16 DSP56367 MOTOROLA Bootstrap ROM Contents ...
Page 432: ...C 8 DSP56367 MOTOROLA JTAG BSDL ...
Page 484: ...D 52 DSP56367 MOTOROLA Programmer s Reference ...
Page 490: ...E 6 DSP56367 MOTOROLA Power Consumption Benchmark ...
Page 516: ...F 26 DSP56367 MOTOROLA IBIS Model ...
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