User Manual
452
Rev. 1.1
2019-03-18
TLE984xQX
Microcontroller with LIN and Power Switches for Automotive Applications
General Purpose Timer Units (GPT12)
Timers T2 and T4 in Reload Mode
Reload Mode for an auxiliary timer Tx is selected by setting bitfield TxM in the respective register TxCON to
100
B
. In reload mode, the core timer T3 is reloaded with the contents of an auxiliary timer register, triggered
by one of two different signals. The trigger signal is selected the same way as the clock source for Counter
Mode (see
), i.e. a transition of the auxiliary timer’s input TxIN or the toggle latch T3OTL may trigger
the reload.
Note:
When programmed for reload mode, the respective auxiliary timer (T2 or T4) stops independently of
its run flag T2R or T4R.
The timer input pin TxIN must be configured as input if it shall trigger a reload operation.
Figure 100 GPT1 Auxiliary Timer in Reload Mode
Upon a trigger signal, T3 is loaded with the contents of the respective timer register (T2 or T4) and the
respective interrupt request flag (T2IR or T4IR) is set.
Note:
When a T3OTL transition is selected for the trigger signal, the interrupt request flag T3IR will also be
set upon a trigger, indicating T3’s overflow or underflow. Modifications of T3OTL via software will
NOT trigger the counter function of T2/T4.
To ensure that a transition of the reload input signal applied to TxIN is recognized correctly, its level must be
held high or low for a minimum number of module clock cycles, detailed in
The reload mode triggered by the T3 toggle latch can be used in a number of different configurations. The
following functions can be performed, depending on the selected active transition:
• If both a positive and a negative transition of T3OTL are selected to trigger a reload, the core timer will be
reloaded with the contents of the auxiliary timer each time it overflows or underflows. This is the standard
reload mode (reload on overflow/underflow).
• If either a positive or a negative transition of T3OTL is selected to trigger a reload, the core timer will be
reloaded with the contents of the auxiliary timer on every second overflow or underflow.
• Using this “single-transition” mode for both auxiliary timers allows to perform very flexible Pulse Width
Modulation (PWM). One of the auxiliary timers is programmed to reload the core timer on a positive
transition of T3OTL, the other is programmed for a reload on a negative transition of T3OTL. With this
combination the core timer is alternately reloaded from the two auxiliary timers.
MCA05400
Toggle Latch
T3OUT
T3IRQ
Count
T3R
Core Timer T3
Operating
Mode
Control
BPS1
TxI
Up/Down
T3IN
f
GPT
Auxiliary
Timer Tx
TxI
Reload
0
1
MUX
TxI.2
TxIN
TxIRQ
x = 2, 4
Edge
Select