PXN20RM Datasheet, PDF (1069/1376 Pages) Freescale Semiconductor, Inc – PXN20 Microcontroller

Chapter 33
Cross Triggering Unit (CTU)
33.1 Introduction
The Cross Triggering Unit (CTU) is a collection of 9-bit down-counters with an exponential prescaler able
to generate the trigger event for the ADC conversion. The delayed trigger event can be a combination of
unified channel flags/triggering events connected to different timers (eMIOS/PIT) present in the system.
The 7-bit channel number is provided to the ADC. This channel number is used to communicate which
particular channel has to be converted.
NOTE
The CTU is not implemented on the PXN20.
33.2 Main Features
• 9-bit down-counters counting from a programmable start value to 0
• Different counters associated with different channel groups
• Channel group is defined based on PWM channel clock
• Different delay value for each eMIOS flag/PIT event
• 4-bit programmable exponential prescaler: f_{CK_TIM} divided by 1, 2, 4, 8, 16, 32, 64, 128, 256, 512,
1024
• Single cycle delayed trigger output. The trigger output is a combination of 33 input flags/events
connected to different timers in the system.
• Maskable interrupt generation whenever a trigger output is generated
• Event configuration registers dedicated to each UC flag/triggering event storing the values of a
channel number to be provided for ATD conversion, CLR_FLAG bit, counter selection bits, delay
value selection bits and trigger masking for each UC flag/triggering event
• Acknowledgment signal to eMIOS/PIT for clearing the flag
• Synchronization with ADC to avoid collision
33.3 Block Diagram
The block diagram is shown in Figure 33-1.
Freescale Semiconductor
PXN20 Microcontroller Reference Manual, Rev. 1
33-1