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19 SPI
19.2 SPI I/O Pins
Table 19.2.1 lists the SPI pins.
Pin name
I/O
SDI (P20)
I
SDO (P21)
O
SPICLK (P22)
I/O
#SPISS (P17)
I
The SPI input/output pins (SDI, SDO, SPICLK, #SPISS) are shared with the I/O ports (P20, P21, P22, P17)
and they are initialized as general-purpose I/O port pins by default. Before using these pins for the SPI, the pin
functions must be switched using the P2_PMUX and P1_PMUX registers. Set the control bits shown below to 1 to
configure the pins for the SPI.
P20 → SDI
∗ P20MUX: P20 Port Function Select Bit in the P2 Port Function Select (P2_PMUX) Register (D0/0x52a2)
P21 → SDO
∗ P21MUX: P21 Port Function Select Bit in the P2 Port Function Select (P2_PMUX) Register (D1/0x52a2)
P22 → SPICLK
∗ P22MUX: P22 Port Function Select Bit in the P2 Port Function Select (P2_PMUX) Register (D2/0x52a2)
P17 → #SPISS
∗ P17MUX: P17 Port Function Select Bit in the P1 Port Function Select (P1_PMUX) Register (D7/0x52a1)
For details on switching pin function, see Section 10.2, "Selecting I/O Pin Functions (Port MUX)."
19-2
Table 19.2.1 List of SPI Pins
Size
1
SPI data input pin
This pin inputs serial data from the SPI bus.
1
SPI data output pin
This pin outputs serial data to the SPI bus.
1
SPI external clock input/output pin
This pin outputs the SPI clock when the SPI is in master mode.
This pin inputs an external clock when the SPI is in slave mode.
1
SPI slave select signal (active low) input pin
A low level input to this pin selects this SPI device in slave mode.
EPSON
Function
S1C17704 TECHNICAL MANUAL
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