User manual

...the world's most energy friendly microcontrollers
2012-04-24 - Giant Gecko Family - d0053_Rev0.96 164
www.energymicro.com
13 PRS - Peripheral Reflex System
0
1 2 3 4
Timer
ADC
DMA
PRS
Ch
PRS
Ch
Quick Facts
What?
The PRS (Peripheral Reflex System)
allows configurable, fast, and autonomous
communication between the peripherals.
Why?
Events and signals from one peripheral
can be used as input signals or triggers by
other peripherals and ensure timing-critical
operation and reduced software overhead.
How?
Without CPU intervention the peripherals can
send Reflex signals (both pulses and level)
to each other in single- or chained steps. The
peripherals can be set up to perform actions
based on the incoming Reflex signals. This
results in improved system performance and
reduced energy consumption.
13.1 Introduction
The Peripheral Reflex System (PRS) system is a network which lets the different peripheral module
communicate directly with each other without involving the CPU. Peripheral modules which send out
Reflex signals are called producers. The PRS routes these reflex signals to consumer peripherals which
apply actions depending on the Reflex signals received. The format for the Reflex signals is not given,
but edge triggers and other functionality can be applied by the PRS.
13.2 Features
• 12 configurable interconnect channels
• Each channel can be connected to any producing peripheral
• Consumers can choose which channel to listen to
• Selectable edge detector (Rising, falling and both edges)
• Software controlled channel output
• Configurable level
• Triggered pulses
13.3 Functional Description
An overview of the PRS module is shown in Figure 13.1 (p. 165) . The PRS contains 12 interconnect
channels, and each of these can select between all the output Reflex signals offered by the producers.
The consumers can then choose which PRS channel to listen to and perform actions based on the Reflex
signals routed through that channel. The Reflex signals can be both pulse signals and level signals.
Synchronous PRS pulses are one HFPERCLK cycle long, and can either be sent out by a producer (e.g.
ADC conversion complete) or be generated from the edge detector in the PRS channel. Level signals
can have an arbitrary waveform (e.g. Timer PWM output).