MFC2000 datasheet(358/426 Pages) ETC

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MFC2000 Multifunctional Peripheral Controller 2000

Hardware Description

19-8

Conexant

100723A

19.3.2 Request/Acknowledge Timing

Request/Acknowledge handshaking may be used while the SSIF is operating in the slave mode. While in this

mode the peripheral (master) may initiate a data transfer by driving the SSACK signal low. The SSACK signal

from the external peripheral is connected to any GPIO pin (used as GPI). Firmware will in turn write SSTXD data

to the data register. This will cause the SSIF hardware to drive the SSREQ(SSSTAT) signal low. Once the

SSREQ is low the peripheral may start the SSCLK to transfer the data. Upon completion of the 8 bit transfer, the

peripheral must drive the SSACK high. The IFC will then read the serial data out of the input register which will in

turn drive the SSREQ high and complete the transfer. If the IFC wishes to initiate a transfer in this mode it must

write to the SSIF output register which will in turn set the SSREQ low. The peripheral must then provide 8 clocks on

the SSCLK line to receive the data from the MFC2000’s SSIF.

P r eip h er al In itiated Tr an sfer

SSA C K n

SSR E Q n

SS C L K

Ser ia l in F u ll

Rea d

Tr an sfer C om p lete

Wr ite

AM F P C In itiate s T r an sfer

Figure 19-4. Timing Diagram

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