Z8F6421PM020SC Datasheet, PDF (150/299 Pages) Zilog, Inc. – High Performance 8-Bit Microcontrollers Z8 Encore-R 64K Series

Z8 Encore!^® 64K Series
Product Specification
130
SCK
(CLKPOL = 0)
SCK
(CLKPOL = 1)
MOSI
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
MISO
Input Sample Time
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SS
Figure 26. SPI Timing When PHASE is 1
Multi-Master Operation
In a multi-master SPI system, all SCK pins are tied together, all MOSI pins are tied
together and all MISO pins are tied together. All SPI pins must then be configured in
open-drain mode to prevent bus contention. At any one time, only one SPI device is con-
figured as the Master and all other SPI devices on the bus are configured as Slaves. The
Master enables a single Slave by asserting the SS pin on that Slave only. Then, the single
Master drives data out its SCK and MOSI pins to the SCK and MOSI pins on the Slaves
(including those which are not enabled). The enabled Slave drives data out its MISO pin to
the MISO Master pin.
For a Master device operating in a multi-master system, if the SS pin is configured as an
input and is driven Low by another Master, the COL bit is set to 1 in the SPI Status Regis-
ter. The COL bit indicates the occurrence of a multi-master collision (mode fault error con-
dition).
Slave Operation
The SPI block is configured for slave mode operation by setting the SPIEN bit to 1 and the
MMEN bit to 0 in the SPICTL register and setting the SSIO bit to 0 in the SPIMODE reg-
PS019915-1005
Serial Peripheral Interface