Slave Select (Nss) Pin Management; Figure 257. Master And Three Independent Slaves - STMicroelectronics STM32F05 series Reference Manual

RM0091

Figure 257. Master and three independent slaves

1. As MISO pins of the slaves are connected together, all slaves must have the GPIO configuration of their
MISO pin set as alternate function open-drain (see
page 123.
26.3.4

Slave select (NSS) pin management

In slave mode, the NSS works as a standard "chip select" input and lets the slave
communicate with the master. In master mode, NSS can be used either as output or input.
As an input it can prevent multimaster bus collision, and as an output it can drive a slave
select signal of a single slave.
NSS
MOSI
shift register
MISO
SCK
SPI clock
generator
I/O 1
Master
I/O 2
I/O 3
Doc ID 018940 Rev 1
Serial peripheral interface / inter-IC sound (SPI/I2S)
(1)
Vcc
MOSI
MISO
SCK
NSS
MOSI
MISO
SCK
NSS
MOSI
MISO
SCK
NSS
Section 8.3.7: I/O alternate function input/output on
shift register
Slave 1
shift register
Slave 2
shift register
Slave 3
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