The SPI Slave Select Register (SPISSR) contains an
active-Low, one-hot encoded slave select vector SS
of length N, where N is
the number of slaves set by the No. of Slaves
parameter. The SS
vector occupies the right-most bits of the register. At
most, one bit can be asserted Low. This bit denotes the slave with which the local master
communicates. The bit assignment in the SPISSR is shown in the following figure and
described in the following table.
Bits | Name | Core Access | Reset Value | Description |
---|---|---|---|---|
31:N | Reserved | N/A | N/A | Reserved |
[N–1]:0 | Selected Slave | R/W | 1 |
Active-Low, one-hot encoded slave select vector of length N-bits. N must be ≤ the data bus width (32-bit). The slaves are numbered right to left starting at zero with the LSB. The slave numbers correspond to the indexes of signal SS. |