Datasheet
DocID022799 Rev 6 29/132
STM32L15xCC STM32L15xRC STM32L15xUC STM32L15xVC Functional overview
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3.17.2 Universal synchronous/asynchronous receiver transmitter (USART)
The three USART interfaces are able to communicate at speeds of up to 4 Mbit/s. They
support IrDA SIR ENDEC, are ISO 7816 compliant and have LIN Master/Slave capability.
The three USARTs provide hardware management of the CTS and RTS signals.
All USART interfaces can be served by the DMA controller.
3.17.3 Serial peripheral interface (SPI)
Up to three SPIs are able to communicate at up to 16 Mbits/s in slave and master modes in
full-duplex and half-duplex 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.
The SPIs can be served by the DMA controller.
3.17.4 Inter-integrated sound (I
2
S)
Two standard I2S interfaces (multiplexed with SPI2 and SPI3) are available. They can
operate in master or slave mode, and can be configured to operate with a 16-/32-bit
resolution as input or output channels. Audio sampling frequencies from 8 kHz up to 192
kHz are supported. When either or both of the I2S interfaces is/are configured in master
mode, the master clock can be output to the external DAC/CODEC at 256 times the
sampling frequency.
The I2Ss can be served by the DMA controller.
3.17.5 Universal serial bus (USB)
The STM32L15xxC embeds a USB device peripheral compatible with the USB full-speed
12 Mbit/s. The USB interface implements a full-speed (12 Mbit/s) function interface. It has
software-configurable endpoint setting and supports suspend/resume. The dedicated
48 MHz clock is generated from the internal main PLL (the clock source must use a HSE
crystal oscillator).
3.18 CRC (cyclic redundancy check) calculation unit
The CRC (cyclic redundancy check) calculation unit is used to get a CRC code from a 32-bit
data word and a fixed generator polynomial.
Among other applications, CRC-based techniques are used to verify data transmission or
storage integrity. In the scope of the EN/IEC 60335-1 standard, they offer a means of
verifying the Flash memory integrity. The CRC calculation unit helps compute a signature of
the software during runtime, to be compared with a reference signature generated at link-
time and stored at a given memory location.