Datasheet

Functional overview STM32F401xD STM32F401xE
30/135 DocID025644 Rev 3
3.22 Serial peripheral interface (SPI)
The devices feature up to four SPIs in slave and master modes in full-duplex and simplex
communication modes. SPI1 and SPI4 can communicate at up to 42 Mbit/s, SPI2 and SPI3
can communicate at up to 21 Mbit/s. 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.
The SPI interface can be configured to operate in TI mode for communications in master
mode and slave mode.
3.23 Inter-integrated sound (I
2
S)
Two standard I
2
S interfaces (multiplexed with SPI2 and SPI3) are available. They can be
operated in master or slave mode, in full duplex and simplex communication modes and
can be configured to operate with a 16-/32-bit resolution as an input or output channel.
Audio sampling frequencies from 8 kHz up to 192 kHz are supported. When either or both of
the I
2
S interfaces is/are configured in master mode, the master clock can be output to the
external DAC/CODEC at 256 times the sampling frequency.
All I
2
Sx can be served by the DMA controller.
3.24 Audio PLL (PLLI2S)
The devices feature an additional dedicated PLL for audio I
2
S application. It allows to
achieve error-free I
2
S sampling clock accuracy without compromising on the CPU
performance.
The PLLI2S configuration can be modified to manage an I
2
S sample rate change without
disabling the main PLL (PLL) used for the CPU.
The audio PLL can be programmed with very low error to obtain sampling rates ranging
from 8 kHz to 192 kHz.
In addition to the audio PLL, a master clock input pin can be used to synchronize the I2S
flow with an external PLL (or Codec output).
Table 6. USART feature comparison
USART
name
Standard
features
Modem
(RTS/CTS)
LIN
SPI
master
irDA
Smartcard
(ISO 7816)
Max. baud
rate in Mbit/s
(oversampling
by 16)
Max. baud
rate in Mbit/s
(oversampling
by 8)
APB
mapping
USART1 X X X X X X 5.25 10.5
APB2
(max.
84 MHz)
USART2 X X X X X X 2.62 5.25
APB1
(max.
42 MHz)
USART6 X N.A X X X X 5.25 10.5
APB2
(max.
84 MHz)
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