Spi Legacy Mode - VersaLogic EBX-22 Reference Manual

SPI L M
EGACY ODE
The following tables describe the legacy SPI control registers (SPICONTROL and SPISTATUS)
and data registers (SPIDATA3-0), such as those used on the EBX-11. To enable SPI legacy
mode, the SPI field (bits D6-D5) of the MODCON register (1DFh) must be set to 1h.
SPICONTROL (READ/WRITE) 1D8h
D7
CPOL CPHA
Bit Mnemonic
D7 CPOL
D6 CPHA
D5-D4 SPILEN
D3 MAN_SS
D2-D0 SS
EBX-22 Reference Manual
D6 D5 D4
SPILEN1 SPILEN0
Table 31: SPI Control Register 1 Bit Assignments
Description
SPI Clock Polarity – Sets the SCLK idle state.
0 = SCLK idles low
1 = SCLK idles high
SPI Clock Phase – Sets the SCLK edge on which valid data will be read.
0 = Data read on rising edge
1 = Data read on falling edge
SPI Frame Length – Sets the SPI frame length. This selection works in
manual and auto slave select modes.
SPILEN1 SPILEN0
0 0
0 1
1 0
1 1
SPI Manual Slave Select Mode – This bit determines whether the slave select
lines are controlled through the user software or are automatically controlled by
a write operation to SPIDATA3 (1DDh). If MAN_SS = 0, then the slave select
operates automatically; if MAN_SS = 1, then the slave select line is controlled
manually through SPICONTROL bits SS2, SS1, and SS0.
0 = Automatic, default
1 = Manual
SPI Slave Select – These bits select which slave select will be asserted. The
SSx# pin on the base board will be directly controlled by these bits when
MAN_SS = 1.
SS2 SS1 SS0
0 0 0
0 0 1
0 1 0
0 1 1
1 0 0
1 0 1
1 1 0
1 1 1
Interfaces and Connectors
D3 D2
MAN_SS SS2
Frame Length
8-bit
16-bit
24-bit
32-bit
Slave Select
None, port disabled
SPX Slave Select 0, J17 pin-8
SPX Slave Select 1, J17 pin-9
SPX Slave Select 2, J17 pin-10
SPX Slave Select 3, J17 pin-11
On-Board A/D Converter Slave Select
On-Board Digital I/O Ch 0-Ch 15 Slave Select
On-Board Digital I/O Ch 16-Ch 31 Slave Select
D1 D0
SS1 SS0
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