STM32F100x4, STM32F100x6, STM32F100x8, STM32F100xB
Description
The device can be woken up from Stop mode by any of the EXTI line. The EXTI line
source can be one of the 16 external lines, the PVD output or the RTC alarm.
●
Standby mode
The Standby mode is used to achieve the lowest power consumption. The internal
voltage regulator is switched off so that the entire 1.8 V domain is powered off. The
PLL, the HSI RC and the HSE crystal oscillators are also switched off. After entering
Standby mode, SRAM and register contents are lost except for registers in the Backup
domain and Standby circuitry.
The device exits Standby mode when an external reset (NRST pin), a IWDG reset, a
rising edge on the WKUP pin, or an RTC alarm occurs.
Note:
The RTC, the IWDG, and the corresponding clock sources are not stopped by entering Stop
or Standby mode.
2.14
DMA
The flexible 7-channel general-purpose DMA is able to manage memory-to-memory,
peripheral-to-memory and memory-to-peripheral transfers. The DMA controller supports
circular buffer management avoiding the generation of interrupts when the controller
reaches the end of the buffer.
Each channel is connected to dedicated hardware DMA requests, with support for software
trigger on each channel. Configuration is made by software and transfer sizes between
source and destination are independent.
2
The DMA can be used with the main peripherals: SPI, DAC, I C, USART, all timers and
ADC.
2.15
RTC (real-time clock) and backup registers
The RTC and the backup registers are supplied through a switch that takes power either on
V
supply when present or through the VBAT pin. The backup registers are ten 16-bit
DD
registers used to store 20 bytes of user application data when V power is not present.
DD
The real-time clock provides a set of continuously running counters which can be used with
suitable software to provide a clock calendar function, and provides an alarm interrupt and a
periodic interrupt. 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 power RC has a typical frequency of 40 kHz. The RTC can be calibrated using
an external 512 Hz output to compensate for any natural crystal deviation. The RTC
features a 32-bit programmable counter for long term measurement using the Compare
register to generate an alarm. A 20-bit prescaler is used for the time base clock and is by
default configured to generate a time base of 1 second from a clock at 32.768 kHz.
2.16
Timers and watchdogs
The STM32F100xx devices include an advanced-control timer, six general-purpose timers,
two basic timers and two watchdog timers.
Table 3 compares the features of the advanced-control, general-purpose and basic timers.
Doc ID 16455 Rev 2
17/84
STMICROELECTRONICS [ ST ]
