Serial Peripheral Interface (Spi); Inter-Integrated Sound (I2S); Universal Serial Bus (Usb); Crc (Cyclic Redundancy Check) Calculation Unit - STMicroelectronics STM32L151RE Manual

Functional overview
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
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 STM32L151xE and STM32L152xE devices embed 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.
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