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UM10316_0
© NXP B.V. 2008. All rights reserved.
User manual
Rev. 00.06 — 17 December 2008
423 of 571
1.
How to read this chapter
The contents of this chapter apply to all LPC29xx parts. Note that the ADC0 is available
on LPC2927/29, LPC2930, and LPC2939 only. External start inputs on ADC1 are not
pinned out on the LPC2927/29 and LPC2921/23/25.
2.
MSCSS functional description
The modulation and sampling control subsystem (MSCSS) is a module provided with
ADCs and PWMs. The ADCs can be used to measure voltages while the PWMs can be
used to create various square waveforms or to capture strobes. The combination of the
blocks can be used to control motors.
Three functional blocks in the MSCSS (ADC, PWM, QEI) are described in the following
chapters. The MSCSS timers are functionally identical to the general timers and are
described in
.
The ADCs and PWMs are provided with several trigger inputs and outputs. Two timers are
available for synchronization of all actions.
A complete overview of the synchronization and trigger mechanism is shown in
below:
2.1 Synchronization and trigger features of the MSCSS
The MSCSS contains two internal timers to generate synchronization and carrier pulses
for the ADCs and PWMs.
shows how the timers are connected to the ADC
and PWM modules.
Each ADC module has four start inputs. An ADC conversion is ed when one of the start
ADC conditions is valid:
•
start 0: ADC external start input pin; can be triggered at a positive or negative edge.
Note that this signal is captured in the ADC clock domain
•
start 1: If the ‘preceding’ ADC conversion is ended, the sync_out signal starts an ADC
conversion. This signal is captured in the MSCSS subsystem clock domain. As can be
seen in
, the sync_out of ADC1 is connected to the start 1 input of
ADC2 and the sync_out of ADC2 is connected to the start 1 input of ADC1.
•
start 2: The PWM sync_out can start an ADC conversion. The sync_out signal is
synchronized to the ADC clock in the ADC module. This signal is captured in the
MSCSS subsystem clock domain.
•
start 3: The match outputs from MSCSS timer 0 are connected to the start 3 inputs of
the ADCs. This signal is captured in the ADC clock domain.
UM10316
Chapter 24: LPC29xx Modulation and Sampling Control
Subsystem (MSCSS)
Rev. 00.06 — 17 December 2008
User manual