Buffer Control Register (Spbfcr) - Renesas RZ/A Series User Manual

RZ/A1L Group, RZ/A1LU Group, RZ/A1LC Group
16.3.14

Buffer Control Register (SPBFCR)

SPBFCR resets the number of data units in the transmit buffer (SPTX) or receive buffer (SPRX) and sets the number of
triggering data units.
Bit Bit Name
7 TXRST
6 RXRST
5, 4 TXTRG[1:0]
3 ―
2 to 0 RXTRG[2:0]
R01UH0437EJ0600 Rev.6.00
Jan 29, 2021
Bit: 7 6 5
TXRST RXRST TXTRG[1:0]
Initial value: 0 0 0
R/W: R/W R/W R/W
Initial Value R/W Function
0 R/W Transmit Buffer Data Reset
Resets the transmit buffer to an empty state. Transmit data in the transmit
buffer becomes invalid when this bit is set to 1.
0: Disables the reset operation*.
1: Enables the reset operation
Note: The reset operation is performed after a power-on reset.
0 R/W Receive Buffer Data Reset
Resets the receive buffer to an empty state. Receive data in the receive
buffer becomes invalid when this bit is set to 1.
0: Disables the reset operation*.
1: Enables the reset operation
Note: The reset operation is performed after a power-on reset.
00 R/W Transmit Buffer Data Triggering Number
Specifies the timing at which the transmit buffer empty state is
determined, that is when the SPTEF flag in the status register is set.
When the number of bytes of data in the transmit buffer (SPTX) is equal
to or less than the specified triggering number, the SPTEF flag is set to 1.
00: 7 bytes (1)*
01: 6 bytes (2)*
10: 4 bytes (4)*
11: 0 bytes (8)*
Note: The value in the parenthesis shows the number of available bytes
0 R Reserved
The write value should always be 0. Otherwise, operation cannot be
guaranteed.
000 R/W Receive Buffer Data Triggering Number
Specifies the timing at which the receive buffer full state is determined,
that is when the SPRF flag in the status register is set. When the number
of bytes of data in the receive buffer (SPRX) is equal to or greater than
the specified triggering number, the SPRF flag is set to 1.
000: 1 byte (31)*
001: 2 bytes (30)*
010: 4 bytes (28)*
011: 8 bytes (24)*
100: 16 bytes (16)*
101: 24 bytes (8)*
110: 32 bytes (0)*
111: 5 bytes (27)*
Note: * The value in the parenthesis shows the number of available bytes
16. Renesas Serial Peripheral Interface
4 3 2 1 0
⎯
RXTRG[2:0]
0 0 0 0 0
R/W R R/W R/W R/W
in the transmit buffer (SPTX).
in the receive buffer (SPRX).
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