SPICS
SPICLK
SPISOMI
VCLK
t
C2TDELAY
Basic Operation
1515
SPNU563A – March 2018
Copyright © 2018, Texas Instruments Incorporated
Multi-Buffered Serial Peripheral Interface Module (MibSPI) with Parallel Pin
Option (MibSPIP)
28.2.6.3 Decoded and Encoded Chip Select (Master Only)
In this device, the SPI can connect to up to 6 individual slave devices using chip-selects by routing one
wire to each slave. The 6 chip selects in the control field are directly connected to the 6 pins. The default
value of each chip select (not active) can be configured via the register CSDEF. During a transmission,
the value of the chip select control field (CSNR) of the SPIDAT1 register is driven on the SPICS pins.
When the transmission finishes, the default chip-select value (defined by the CSDEF register) is put on the
SPICS pins.
The SPI can support more than 6 slaves by using encoded chip selects. To connect the SPI with encoded
slaves devices, the CSNR field allows multiple active SPICS pins at the same time, which enables
encoded chip selects from 0 to 16. To use encoded chip selects, all 6 chip select lines have to be
connected to each slave device and each slave needs to have a unique chip-select address. The CSDEF
register is used to provide the address at which slaves devices are all de-selected.
Users can combine decoded and encoded chip selects. For example,
n
SPICS pins can be used for
encoding an
n
-bit address and the remaining pins can be connected to decoded-mode slaves.
28.2.6.4 Chip Select Timing Control
This section describes fields of the control register SPIDELAY. This register decides the chip select and
timing control for the device.
28.2.6.4.1 Chip-Select-Active-to-Transmit-Start-Delay (C2TDELAY)
C2TDELAY is used in master mode only. It defines a setup time for the slave device that delays the data
transmission from the chip select active edge by a multiple of VCLK cycles. Chip Select-active-to-
transmission delays between 2 to 257 VCLK cycles can be achieved.
The setup time value is calculated as:
t
C2TDELAY
= (C2 2) × VCLK Period
is the timing diagram when C2TDELAY of 8 VCLK Cycles.
Figure 28-17. Example: t
C2TDELAY
= 8 VCLK Cycles