Chapter 24 Cross Triggering Unit (CTU)
MPC5602P Microcontroller Reference Manual, Rev. 4
612
Freescale Semiconductor
value written into the double-buffered register (TGSCRR), during the control cycle
n
– 1 and reloads all
the double-buffered registers (such as Trigger Compare registers, TGSCR, TGSCRR itself).
The triggers list registers consist of eight compare registers. Each triggers list register is associated with a
comparator. On reload (MRS occurrence), the comparators are disabled. One TGS clock cycle is necessary
to enable them and to start the counting. The MRS is output together with individual trigger signals. The
MRS can be performed by hardware or by software. The MRS_SG bit in the CTU control register, if set
to 1, generates equivalent software MRS (that is, resets/reloads TGS Counter and reloads all
double-buffered registers). This bit is cleared by each hardware or software MRS occurrence.
The TGS counter compare register and the TGS counter comparator are used to stop the TGS counter when
it reaches the value stored in the TGS counter compare register before an MRS occurs.
The prescaler for TGS and SU can be 1,2,3,4 (PRES bits in the TGS Control Register).
An example timing for the TGS in Triggered Mode is shown in
MRS occurrences, while the black arrows indicate the trigger event occurrences, with the relevant delay
in respect to the last MRS occurrence.
Figure 24-3. Example timing for TGS in triggered mode
24.3.4
TGS in sequential mode
The structure of the TGS in sequential mode is shown in
The 32 input events (16 signals with two edges for signal), which can be individually enabled, are ORed
in order to generate the event signal (ES). The ES enables the reload of the TGS counter register and pilots
the 3-bit counter in order to select the next active trigger. One of the 32 input events can be selected,
through the MRS_SM (master reload selection sequential mode) bits in the TGS control register, to be the
MRS, that enables the reload of the triggers list and resets the 3-bit counter (incoming events counter), that
is, the MRS is the signal linked with the control cycle defined as the time window between two consecutive
MRSs. In this mode, each incoming event sequentially enables only one trigger event through the 3-bit
counter and the MUX. The MUX is a selection switch that enables, according to the number of event
signals occurred, only one of the eight trigger signals to the scheduler subunit. Sequences of as many as
eight trigger events can be supported within this control cycle.
For the other features see the previous paragraphs.
Delay T
0
Delay T
1
Delay T
2
Delay T
2