NetduinoPlus2 Netduino, NetduinoPlus2 Datasheet - Page 27

• Manufacturer Part Number: NetduinoPlus2
• Description: Development Boards & Kits - ARM NETDUINO PLUS 2
• Manufacturer: Netduino

Specifications of NetduinoPlus2

• Rohs: yes
• Product: Development Boards
• Tool Is For Evaluation Of: STM32F405RG
• Core: ARM Cortex M4
• Interface Type: I2C, SPI, UART, USB
• Operating Supply Voltage: 7.5 v to 9 V
• Data Bus Width: 32 bit
• Description/function: Arduino form factor
• Dimensions: 2.8 in x 2.1 in
• Maximum Operating Temperature: + 70 C
• Minimum Operating Temperature: 0 C

STM32F405xx, STM32F407xx
2.2.17
2.2.18
Real-time clock (RTC), backup SRAM and backup registers
The backup domain of the STM32F405xx and STM32F407xx includes:
●
●
●
The real-time clock (RTC) is an independent BCD timer/counter. Dedicated registers contain
the second, minute, hour (in 12/24 hour), week day, date, month, year, in BCD (binary-coded
decimal) format. Correction for 28, 29 (leap year), 30, and 31 day of the month are
performed automatically. The RTC provides a programmable alarm and programmable
periodic interrupts with wakeup from Stop and Standby modes. The sub-seconds value is
also available in binary format.
It is clocked by a 32.768 kHz external crystal, resonator or oscillator, the internal low-power
RC oscillator or the high-speed external clock divided by 128. The internal low-speed RC
has a typical frequency of 32 kHz. The RTC can be calibrated using an external 512 Hz
output to compensate for any natural quartz deviation.
Two alarm registers are used to generate an alarm at a specific time and calendar fields can
be independently masked for alarm comparison. To generate a periodic interrupt, a 16-bit
programmable binary auto-reload downcounter with programmable resolution is available
and allows automatic wakeup and periodic alarms from every 120 µs to every 36 hours.
A 20-bit prescaler is used for the time base clock. It is by default configured to generate a
time base of 1 second from a clock at 32.768 kHz.
The 4-Kbyte backup SRAM is an EEPROM-like memory area. It can be used to store data
which need to be retained in VBAT and standby mode. This memory area is disabled by
default to minimize power consumption (see
enabled by software.
The backup registers are 32-bit registers used to store 80 bytes of user application data
when V
or when the device wakes up from the Standby mode (see
modes).
Additional 32-bit registers contain the programmable alarm subseconds, seconds, minutes,
hours, day, and date.
Like backup SRAM, the RTC and backup registers are supplied through a switch that is
powered either from the V
Low-power modes
The STM32F405xx and STM32F407xx support three low-power modes to achieve the best
compromise between low power consumption, short startup time and available wakeup
sources:
●
●
The real-time clock (RTC)
4 Kbytes of backup SRAM
20 backup registers
Sleep mode
In Sleep mode, only the CPU is stopped. All peripherals continue to operate and can
wake up the CPU when an interrupt/event occurs.
Stop mode
The Stop mode achieves the lowest power consumption while retaining the contents of
SRAM and registers. All clocks in the 1.2 V domain are stopped, the PLL, the HSI RC
DD
power is not present. Backup registers are not reset by a system, a power reset,
DD
supply when present or from the V
Doc ID 022152 Rev 3
Section 2.2.18: Low-power
Section 2.2.18: Low-power
BAT
pin.
modes). It can be
Description
27/180