Value
Description
Data Pins
1
Dual
DQ0, DQ1
2
Quad
DQ0, DQ1, DQ2, DQ3
Value
Description
0
Transmit most-significant bit (MSB) first
1
Transmit least-significant bit (LSB) first
Value
Description
0
Rx: For dual and quad protocols, the DQ pins are tri-stated. For the single protocol,
the DQ0 pin is driven with the transmit data as normal.
1
Tx: The receive FIFO is not populated.
Writing to the
txdata
register loads the transmit FIFO with the value contained in the
data
field.
For
fmt.len
< 8, values should be left-aligned when
fmt.endian
= MSB and right-aligned
when
fmt.endian
= LSB.
The
full
flag indicates whether the transmit FIFO is ready to accept new entries; when set,
writes to
txdata
are ignored. The
data
field returns
0x0
when read.
Transmit Data Register (
txdata
)
Register Offset
0x48
Bits
Field Name
Attr.
Rst.
Description
[7:0]
data
RW
0x0
Transmit data
[30:8]
Reserved
31
full
RO
X
FIFO full flag
Table 76:
SPI Protocol. Unused DQ pins are tri-stated.
Table 77:
SPI Endianness
Table 78:
SPI I/O Direction
Table 79:
Transmit Data Register
Chapter 18 Serial Peripheral Interface (SPI)
FE310-G003 Manual
© SiFive, Inc.
Page 94
Содержание FE310-G003
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