Infineon TLE984 QX Series, Руководство пользователя

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User Manual 454 Rev. 1.1
2019-03-18
TLE984xQX
Microcontroller with LIN and Power Switches for Automotive Applications
General Purpose Timer Units (GPT12)
For both ways, the basic clock determines the maximum count frequency and the timer’s resolution:
Note: When initializing the GPT1 block, and the block prescaler BPS1 in register T3CON needs to be set to
a value different from its reset value (00
B
), it must be initialized first before any mode involving
external trigger signals is configured. These modes include counter, incremental interface, capture,
and reload mode. Otherwise, unintended count/capture/reload events may occur.
In this case (e.g. when changing BPS1 during operation of the GPT1 block), disable related interrupts
before modification of BPS1, and afterwards clear the corresponding service request flags and re-
initialize those registers (T2, T3, T4) that might be affected by a count/capture/reload event.
Internal Count Clock Generation
In Timer Mode and Gated Timer Mode, the count clock for each GPT1 timer is derived from the GPT1 basic
clock by a programmable prescaler, controlled by bitfield TxI in the respective timer’s control register TxCON.
The count frequency
f
Tx
for a timer Tx and its resolution r
Tx
are scaled linearly with lower clock frequencies, as
can be seen from the following formula:
(16.1)
The effective count frequency depends on the common module clock prescaler factor F(BPS1) as well as on
the individual input prescaler factor 2
<TxI>
. Table 251 summarizes the resulting overall divider factors for a
GPT1 timer that result from these cascaded prescalers.
Table 240 lists GPT1 timer’s parameters (such as count frequency, resolution, and period) resulting from the
selected overall prescaler factor and the module clock f
GPT
. Note that some numbers may be rounded.
Table 239 Basic Clock Selection for Block GPT1
Block Prescaler
1)
1) Please note the non-linear encoding of bitfield BPS1.
BPS1 = 01
B
BPS1 = 00
B
2)
2) Default after reset.
BPS1 = 11
B
BPS1 = 10
B
Prescaling Factor for GPT1:
F(BPS1) F(BPS1)
= 4 F(BPS1)
= 8 F(BPS1)
= 16 F(BPS1)
= 32
Maximum External Count
Frequency f
GPT
/8 f
GPT
/16 f
GPT
/32 f
GPT
/64
Input Signal Stable Time 4 × t
GPT
8 × t
GPT
16 × t
GPT
32 × t
GPT
Table 240 GPT1 Timer Parameters
Module Clock f
GPT
= 10 MHz Overall
Prescaler
Factor Module Clock f
GPT
= 40 MHz
Frequency Resolution Period Frequency Resolution Period
2.5 MHz 400 ns 26.21 ms 4 10.0 MHz 100 ns 6.55 ms
1.25 MHz 800 ns 52.43 ms 8 5.0 MHz 200 ns 13.11 ms
625.0 kHz 1.6 µs 104.9 ms 16 2.5 MHz 400 ns 26.21 ms
312.5 kHz 3.2 µs 209.7 ms 32 1.25 MHz 800 ns 52.43 ms
156.25 kHz 6.4 µs 419.4 ms 64 625.0 kHz 1.6 µs 104.9 ms
78.125 kHz 12.8 µs 838.9 ms 128 312.5 kHz 3.2 µs 209.7 ms
39.06 kHz 25.6 µs 1.678 s 256 156.25 kHz 6.4 µs 419.4 ms
f
Tx
=
f
GPT
F BPS1
(
)
•
<Txl>
2
r
Tx
[
μ
s]
=
f
GPT
[MHz]
F BPS1 ( )
•
<Txl>
2