Introduction
1-10
Freescale Semiconductor
PXR40 Microcontroller Reference Manual, Rev. 1
1.2.10
Periodic interrupt timer (PIT)
The periodic interrupt timer (PIT) is an array of timers that can be used to generate interrupts and trigger
DMA channels. It also provides a dedicated real-time interrupt timer (RTI), which runs on a separate clock
and can be used for system wake-up.
The following features are implemented:
•
Four independent timer channels
•
Each channel includes 32-bit wide down counter with automatic reload
•
Three channels clocked from system clock
•
One channel clocked from crystal clock (wake-up timer)
•
Wake-up timer remains active when system enters stop mode. Used to restart system clock after
predefined time-out period
•
Each channel can optionally generate interrupt request when timer reaches zero
•
Channels can optionally produce trigger event when timer reaches zero (used to trigger eQADC
queues)
1.2.11
System timer module (STM)
The system timer module (STM) is a 32-bit timer designed to support commonly required operating
system and application software timing functions. The STM includes a 32-bit up counter and four 32-bit
compare channels with a separate interrupt source for each channel.
The following features are implemented:
•
One 32-bit up counter with 8-bit prescaler
•
Four 32-bit compare channels
•
Independent interrupt source for each channel
•
Counter can be stopped in debug mode
1.2.12
Enhanced queued analog to digital converter (eQADC)
The enhanced queued analog to digital converter (eQADC) block provides accurate and fast conversions
for a wide range of applications. The two eQADCs on the PXR40 provide a parallel interface to four
on-chip analog to digital converters (ADC), and a single-master to single-slave serial interface to an
off-chip external device.
The ADCs include features designed to allow the direct connection of high impedance acoustic sensors
that might be used in a system for detecting engine knock. These features include differential inputs;
integrated variable gain amplifiers for increasing the dynamic range; programmable pullup and pulldown
resistors for biasing and sensor diagnostics.
eQADC_B also integrates four programmable decimation filters capable of taking in ADC conversion
results at a high rate, passing them through a hardware low-pass filter, then down-sampling the output of
the filter and feeding the lower sample rate results to the result FIFOs. This allows the ADCs to sample
the sensor at a rate high enough to avoid aliasing of out-of-band noise, while providing a reduced sample
Summary of Contents for PXR4030
Page 1: ...PXR40 Microcontroller Reference Manual Devices Supported PXR4030 PXR4040 PXR40RM Rev 1 06 2011...
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Page 66: ...Memory Map PXR40 Microcontroller Reference Manual Rev 1 2 4 Freescale Semiconductor...
Page 120: ...Signal Descriptions 3 54 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Page 860: ...FlexCAN Module 24 50 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Page 1167: ...Decimation Filter Freescale Semiconductor 28 53 PXR40 Microcontroller Reference Manual Rev 1...
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