User's Manual

GS2101M Low Power WiFi Module Data Sheet GS2101M Architecture
Architecture Description
GS2101M-DS-001270, Release 1.0 Confidential 29
2.1.6 Real Time Clock (RTC) Overview
To provide global time (and date) to the system, the GS2101Mxx module is equipped with
a low-power Real Time Clock (RTC). The RTC is the always on block that manages the
Standby state. This block is powered from a supply pin (VRTC) separate from the digital
core and may be powered directly from a battery. The RTC implementation supports a
voltage range of 1.6V to 3.6V.
2.1.6.1 RTC Main Features
• One 48-bit primary RTC counter as the primary reference for all timing events and
standby awake management
• 1 programmable IO pins with specific default behavior. These pins are in the RTC
IO domain.
– Alarm inputs to wake up the GS2101M module from its sleep states
(deep-sleep/standby)
• Startup control counters with HW and SW override registers
• Power-on-reset control with brown-out detector
• RTC registers to hold RTC and wakeup control bits while the core domain is off
• 1Kbyte latch based memory (1.6-3.6V capable)
• 16KB of SRAM memory, divided into 4 equal blocks (1.2V capable)
• uLDO to supply the SRAM memory
• RTC logic is 1.6-3.6V capable
• 32 KHz RC oscillator
• 32768Hz crystal oscillator
• APB interface for CPU access
• Interrupts to CPU
The RTC contains a low-power 32.768KHz RC oscillator which provides fast startup at
first application of RTC power. It also supports an optional 32.768KHz crystal oscillator
which can be substituted for the RC oscillator under software control. In normal operation
the RTC is always powered up.
The standby programmable counter is 48-bits and provides up to 272 years worth of
standby duration. For the RTC_IO pin, the programmable embedded counter (32-bit) is
provided to enable periodic wake-up of the remainder of the external system, and provide
a 1.5 days max period. The RTC_IO pin can be configured as input (ALARM) or output
(WAKE UP) pin.
The RTC includes a Power-On Reset (POR) circuit, to eliminate the need for an external
component. The RTC contains low-leakage non-volatile (battery-powered) RAM, to
enable storage of data that needs to be preserved. It also includes a brown-out detector that
can be disabled by SW.