Datasheet

DS5792 Rev 13 21/143
STM32F103xC, STM32F103xD, STM32F103xE Description
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the main clock. It has an early warning interrupt capability and the counter can be frozen in
debug mode.
SysTick timer
This timer is dedicated to real-time operating systems, but could also be used as a standard
down counter. It features:
• A 24-bit down counter
• Autoreload capability
• Maskable system interrupt generation when the counter reaches 0.
• Programmable clock source
2.3.18 I²C bus
Up to two I²C bus interfaces can operate in multimaster and slave modes. They can support
standard and fast modes.
They support 7/10-bit addressing mode and 7-bit dual addressing mode (as slave). A
hardware CRC generation/verification is embedded.
They can be served by DMA and they support SMBus 2.0/PMBus.
2.3.19 Universal synchronous/asynchronous receiver transmitters (USARTs)
The STM32F103xC, STM32F103xD and STM32F103xE performance line embeds three
universal synchronous/asynchronous receiver transmitters (USART1, USART2 and
USART3) and two universal asynchronous receiver transmitters (UART4 and UART5).
These five interfaces provide asynchronous communication, IrDA SIR ENDEC support,
multiprocessor communication mode, single-wire half-duplex communication mode and
have LIN Master/Slave capability.
The USART1 interface is able to communicate at speeds of up to 4.5 Mbit/s. The other
available interfaces communicate at up to 2.25 Mbit/s.
USART1, USART2 and USART3 also provide hardware management of the CTS and RTS
signals, Smart Card mode (ISO 7816 compliant) and SPI-like communication capability. All
interfaces can be served by the DMA controller except for UART5.
2.3.20 Serial peripheral interface (SPI)
Up to three SPIs are able to communicate up to 18 Mbits/s in slave and master modes in
full-duplex and simplex communication modes. The 3-bit prescaler gives 8 master mode
frequencies and the frame is configurable to 8 bits or 16 bits. The hardware CRC
generation/verification supports basic SD Card/MMC modes.
All SPIs can be served by the DMA controller.
2.3.21 Inter-integrated sound (I
2
S)
Two standard I
2
S interfaces (multiplexed with SPI2 and SPI3) are available, that can be
operated in master or slave mode. These interfaces can be configured to operate with 16/32
bit resolution, as input or output channels. Audio sampling frequencies from 8 kHz up to
48 kHz are supported. When either or both of the I
2
S interfaces is/are configured in master