DP83907 datasheet(55/70 Pages) NSC

55 / 70 page

60 Operation of DP83907 (Continued)

16-Bit IO Slave Read

TLF12082 – 38

This is the type of cycle used to read from a data transfer port in 16-bit mode These accesses are entirely asynchronous with

the DP83907 responding when it decodes the correct address on SA0 – 9 and an IORD If AEN is high the cycle will be ignored

CHRDY is deasserted if the DP83907 is not ready to respond and asserted when ready If it is ready immediately CHRDY is not

deasserted IO16 is generated when an address within the DP83907’s data transfer port is decoded to indicate to the system

that this is a 16-bit transfer If the IO16CON bit in Configuration Register B is low then it will be a straight decode of the SA0 – 9

lines If that bit is high the IO16 output will be generated after IORD goes active to indicate that this is a 16-bit transfer and the

address should be even SA0 low The data will appear on SD0 – 15

16-Bit IO Slave Write

TLF12082 – 39

This is the type of cycle used to write to a data transfer port in 16-bit mode These accesses are entirely asynchronous with the

DP83907 responding when it decodes the correct address on SA0 – 9 and an IOWR If AEN is high the cycle will be ignored

CHRDY is deasserted if the DP83907 is not ready to respond and asserted when ready If it is ready immediately CHRDY is not

deasserted IO16 is generated when an address within the DP83907’s data transfer port is decoded to indicate to the system

that this is a 16-bit transfer If the IO16CON bit in Configuration Register B is low then it will be a straight decode of the SA0 – 9

lines If that bit is high the IO16 output will be generated after IOWR goes active to indicate that this is a 16-bit transfer and the

address should be even SA0 low The data will be taken from SD0 – 15

DP83907 Datasheet(PDF) 55 Page - National Semiconductor (TI)