C8051F960-B-GM Datasheet, PDF (312/492 Pages) Silicon Laboratories – Ultra Low Power 128K, LCD MCU Family

C8051F96x
25. Low-Power Pulse Counter
The C8051F96x family of microcontrollers contains a low-power Pulse Counter module with advanced fea-
tures, such as ultra low power input comparators, a wide range of pull up values with a self calibration
engine, asymmetrical integrators for low pass filtering and switch debounce, single, dual, and quadrature
modes of operation, two 24-bit counters, threshold comparators, and a variety of interrupt and sleep wake
up capabilities. This combination of features provides water, gas, and heat metering system designers with
an optimal tool for saving power while collecting meter usage data.
PC0PCF
PC0
PC1
VBAT
PC0DCH
PC0DCL
debounce
debounce
PC0TH
Comparator 0
PC0CMP0H:M:L
Logic
PC0MD
Counter 0
PC0CTR0H:M:L
Counter 1
PC0CTR1H:M:L
Comparator 1
PC0CMP1H:M:L
Figure 25.1. Pulse Counter Block Diagram
PC0INT0
The low-power Pulse Counter is a low-power sleep-mode peripheral designed primarily to work meters
using reed switches, including water and gas meters. The Pulse Counter is very flexible and can count
pulses from many different types of sources.
The Pulse Counter operates in sleep mode to enable ultra-low power metering systems. The MCU does
not have to wake up on every edge or transition and can remain in sleep mode while the Pulse Counter
counts pulses for an extended period of time. The Pulse Counter includes two 24-bit counters. These
counters can count up to 16,777,215 (2²⁴-1) transitions in sleep mode before overflowing. The Pulse
Counter can wake up the MCU when one of the counters overflows. The Pulse Counter also has two 24-bit
comparators. The comparators have the ability to wake up the MCU when the one of the counters reaches
a predetermined threshold.
The Pulse Counter uses the RTC clock for sampling, de-bouncing, and managing the low-power pull-up
resistors. The RTC must be enabled when counting pulses. The RTC alarms can wake up the MCU peri-
odically to read the pulse counters, instead of using the Pulse Counter comparators. For example, the RTC
can wake up the MCU every five minutes. The MCU can then read the Pulse Counter and transmit the
information using the UART or a wireless transceiver.
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