Datasheet

Table Of Contents
NOTE
The SSP (PL022) does not support dynamic switching between master and slave in a system. Each instance is
configured and connected either as a master or slave.
Figure 97 shows the PrimeCell SSP (PL022) instanced twice, as a single master and one slave. The master can broadcast
to the slave through the master SSPTXD line. In response, the slave drives its nSSPOE signal HIGH, enabling its SSPTXD
data onto the SSPRXD line of the master.
PL022 configured
as master
PL022 configured
as slave
SSPRXD
nSSPOE
SSPTXD
SSPFSSIN
SSPFSSOUT
SSPCLKIN
nSSPCTLOE
SSPCLKOUT
SSPTXD
nSSPOE
SSPRXD
SSPFSSOUT
SSPFSSIN
SSPCLKOUT
nSSPCTLOE
SSPCLKIN
OV
OV
Figure 97. PrimeCell
SSP master coupled to
a PL022 slave
Figure 98 shows how an PrimeCell SSP (PL022), configured as master, interfaces to a Motorola SPI slave. The SPI Slave
Select (SS) signal is permanently tied LOW and configures it as a slave. Similar to the above operation, the master can
broadcast to the slave through the master PrimeCell SSP SSPTXD line. In response, the slave drives its SPI MISO port
onto the SSPRXD line of the master.
PL022 configured
as master
SPI slave
MOSI
MISO
SCK
SS
SSPTXD
nSSPOE
SSPRXD
SSPFSSOUT
SSPFSSIN
SSPCLKOUT
nSSPCTLOE
SSPCLKIN
OV
OV
Figure 98. PrimeCell
SSP master coupled to
an SPI slave
Figure 99 shows a Motorola SPI configured as a master and interfaced to an instance of a PrimeCell SSP (PL022)
configured as a slave. In this case, the slave Select Signal (SS) is permanently tied HIGH to configure it as a master. The
master can broadcast to the slave through the master SPI MOSI line and in response, the slave drives its nSSPOE signal
LOW. This enables its SSPTXD data onto the MISO line of the master.
RP2040 Datasheet
4.5. SPI 538