Datasheet
LPC2194 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2011. All rights reserved.
Product data sheet Rev. 6 — 14 June 2011 18 of 41
NXP Semiconductors
LPC2194
Single-chip 16/32-bit microcontroller
• Flag to indicate watchdog reset.
• Programmable 32-bit timer with internal pre-scaler.
• Selectable time period from (T
cy(PCLK)
256 4) to (T
cy(PCLK)
2
32
4) in multiples of
T
cy(PCLK)
4.
6.16 Real-time clock
The RTC is designed to provide a set of counters to measure time when normal or idle
operating mode is selected. The RTC has been designed to use little power, making it
suitable for battery powered systems where the CPU is not running continuously (Idle
mode).
6.16.1 Features
• Measures the passage of time to maintain a calendar and clock.
• Ultra low power design to support battery powered systems.
• Provides Seconds, Minutes, Hours, Day of Month, Month, Year, Day of Week, and
Day of Year.
• Programmable reference clock divider allows adjustment of the RTC to match various
crystal frequencies.
6.17 Pulse width modulator
The PWM is based on the standard Timer block and inherits all of its features, although
only the PWM function is pinned out on the LPC2194. The Timer is designed to count
cycles of the peripheral clock (PCLK) and optionally generate interrupts or perform other
actions when specified timer values occur, based on seven match registers. The PWM
function is also based on match register events.
The ability to separately control rising and falling edge locations allows the PWM to be
used for more applications. For instance, multi-phase motor control typically requires
three non-overlapping PWM outputs with individual control of all three pulse widths and
positions.
Two match registers can be used to provide a single edge controlled PWM output. One
match register (MR0) controls the PWM cycle rate, by resetting the count upon match.
The other match register controls the PWM edge position. Additional single edge
controlled PWM outputs require only one match register each, since the repetition rate is
the same for all PWM outputs. Multiple single edge controlled PWM outputs will all have a
rising edge at the beginning of each PWM cycle, when an MR0 match occurs.
Three match registers can be used to provide a PWM output with both edges controlled.
Again, the MR0 match register controls the PWM cycle rate. The other match registers
control the two PWM edge positions. Additional double edge controlled PWM outputs
require only two match registers each, since the repetition rate is the same for all PWM
outputs.