LPC2917_19_1 © NXP B.V. 2008. All rights reserved.
Product data sheet Rev. 01 — 31 July 2008 32 of 67
NXP Semiconductors
LPC2917/19
ARM9 microcontroller with CAN and LIN
Each ADC module has four start inputs. An ADC conversion is started 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, see
Section 8.7.5.2. As can be seen in Figure 8, 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.
The PWM_sync and trans_enable_in of PWM 0 are connected to the 4th match output of
MSCSS timer 0 to start the PWM after a pre-programmed delay. This sync signal is
cascaded through all PWMs, allowing a programmable delay offset between subsequent
PWMs. The sync delay of each PWM can be programmed synchronously or with a
different phase for spreading the power load.
The match outputs of MSCSS timer 1 (PWM control) are connected to the corresponding
carrier inputs of the PWM modules. The carrier signal is modulated with the PWM-
generated waveforms.
The pause input of MSCSS timer 1 (PWM Control) is connected to an external input pin.
Generation of the carrier signal is stopped by asserting the pause of this timer.
The pause input of MSCSS timer 0 (ADC Control) is connected to a ‘NOR’ of the
PWM_sync outputs (start 2 input on the ADCs). If the pause feature of this timer is
enabled the timer only counts when one of the PWM_sync outputs is active HIGH. This
feature can be used to start the ADC once every x PWM cycles, where x corresponds to
the value in the match register of the timer. In this case the start 3 input of the ADC should
be enabled (start on match output of MSCSS timer 0).
The signals connected to the capture inputs of the timers (both MSCSS timer 0 and
MSCSS timer 1) are intended for debugging.
