Peripherals—IP2022 User’s Manual 318 www.ubicom.com 4.10    Parallel Slave Peripheral The Parallel Slave Peripheral allows the IP2022 to operate as an
8- or 16-bit slave to an external device, much like a memory chip.
Alternate functions of Port C and Port D are used for transferring
data, and alternate functions of Port B are used for control signals.
Figure 4-17 shows the connections between an external master
and the Parallel Slave Peripheral interface. Figure 4-17  Parallel Slave Peripheral Interface To read or write through the Parallel Slave Peripheral interface,
the external master asserts the chip select (CS) signal low. This
signal  is an alternate function of port pin RB7.  The direction of
transfer  is  indicated  by  the  R/W  signal,  which  is  an  alternate
function of port pin RB6. When the R/W signal is high, the master
is reading from the slave. When the R/W signal is low, the master External Master Data Data HOLD IP2022 Slave 515-033.eps R/W CS RB7 RB6 RB5 IOVDD R1 RD7:0 RC7:0