DocID022152 Rev 4
This timer is dedicated to real-time operating systems, but could also be used as a standard
downcounter. It features:
A 24-bit downcounter
Maskable system interrupt generation when the counter reaches 0
Programmable clock source.
Inter-integrated circuit interface (I²C)
Up to three I²C bus interfaces can operate in multimaster and slave modes. They can
support the Standard-mode (up to 100 kHz) and Fast-mode (up to 400 kHz) . They support
the 7/10-bit addressing mode and the 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.
Universal synchronous/asynchronous receiver transmitters (USART)
The STM32F405xx and STM32F407xx embed four universal synchronous/asynchronous
receiver transmitters (USART1, USART2, USART3 and USART6) and two universal
asynchronous receiver transmitters (UART4 and UART5).
These six 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 and USART6 interfaces are able to
communicate at speeds of up to 10.5 Mbit/s. The other available interfaces communicate at
up to 5.25 Mbit/s.
USART1, USART2, USART3 and USART6 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.