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M0A21/M0A23 Series
May 06, 2022
Page
562
of 746
Rev 1.02
M0
A21
/M
0
A
2
3
SE
RIES
TEC
H
NICAL
RE
FEREN
C
E
M
ANUAL
USCI Protocol Control Register
– USPI_PROTCTL (SPI)
Register
Offset
R/W
Description
Reset Value
USPI_PROTCTL
U0x5C
R/W
USCI Protocol Control Register
0x0000_0300
31
30
29
28
27
26
25
24
PROTEN
Reserved
TXUDRPOL
Reserved
SLVTOCNT
23
22
21
20
19
18
17
16
SLVTOCNT
15
14
13
12
11
10
9
8
Reserved
TSMSEL
SUSPITV
7
6
5
4
3
2
1
0
SCLKMODE
Reserved
AUTOSS
SS
SLV3WIRE
SLAVE
Bits
Description
[31]
PROTEN
SPI Protocol Enable Bit
0 = SPI Protocol Disabled.
1 = SPI Protocol Enabled.
[30:29]
Reserved
Reserved.
[28]
TXUDRPOL
Transmit Under-run Data Polarity
This bit defines the transmitting data value of USCIx_DAT1 when no data is available for transferring.
0 = The output data value is 0 if TX under run event occurs.
1 = The output data value is 1 if TX under run event occurs.
Note:
for Slave
[27:26]
Reserved
Reserved.
[25:16]
SLVTOCNT
Slave Mode Time-out Period
In Slave mode, this bit field is used for Slave time-out period. This bit field indicates how many clock periods
(selected by TMCNTSRC, USPI_BRGEN[5]) between the two edges of input SCLK will assert the Slave
time-out event. Writing 0x0 into this bit field will disable the Slave time-out function.
Example: Assume SLVTOCNT is 0x0A and TMCNTSRC (USPI_BRGEN[5]) is 1, it means the time-out
event will occur if the state of SPI bus clock pin is not changed more than (10+1) periods of f
DIV_CLK
.
Note:
Slave only
[15]
Reserved
Reserved.
[14:12]
TSMSEL
Transmit Data Mode Selection
This bit field describes how receive and transmit data is shifted in and out.
TSMSEL = 000b: Full-duplex SPI.
TSMSEL = 100b: Half-duplex SPI.
Other values are reserved.
Note:
Changing the value of this bit field will produce the TXRST and RXRST to clear the TX/RX data buffer
automatically.
[11:8]
SUSPITV
Suspend Interval
This bit field provides the configurable suspend interval between two successive transmit/receive
transaction in a transfer. The definition of the suspend interval is the interval between the last clock edge