LAN9313I SMSC [SMSC Corporation], LAN9313I Datasheet - Page 59

• Manufacturer Part Number: LAN9313I
• Description: Three Port 10/100 Managed Ethernet Switch with MII
• Manufacturer: SMSC [SMSC Corporation]

Three Port 10/100 Managed Ethernet Switch with MII
Datasheet
SMSC LAN9313/LAN9313i
6.2.2
CSR_BUSY = 0
Switch Fabric CSR Reads
To perform a read of an individual switch fabric register, the read cycle must be initiated by performing
a single write to the
CSR_BUSY (bit 31) set, the CSR_ADDRESS field (bits 15:0) set to the desired register address, the
R_nW (bit 30) set, and the AUTO_INC and AUTO_DEC fields cleared. Valid data is available for
reading when the CSR_BUSY bit is cleared, indicating that the data can be read from the
CSR Interface Data Register
A second read method may be used which utilizes the auto increment/decrement function of the
Fabric CSR Interface Command Register (SWITCH_CSR_CMD)
addresses. When using this method, the
(SWITCH_CSR_CMD)
decrement(AUTO_DEC) bit set, the CSR_ADDRESS field written with the desired register address,
and the R_nW bit set. The completion of a read cycle is indicated by the clearing of the CSR_BUSY
bit, at which time the data can be read from the
(SWITCH_CSR_DATA). When the data is read, the address in the
Command Register (SWITCH_CSR_CMD)
read cycle is started automatically. The user should clear the AUTO_INC and AUTO_DEC bits before
reading the last data to avoid an unintended read cycle.
Figure 6.2
CSR Write
Write Data
Command
Command
illustrates the process required to perform a switch fabric CSR read.
Register
Register
Register
Write
Read
Idle
Figure 6.1 Switch Fabric CSR Write Access Flow Diagram
CSR_BUSY = 1
Switch Fabric CSR Interface Command Register (SWITCH_CSR_CMD)
must first be written with the auto increment(AUTO_INC) or auto
CSR_BUSY = 0
(SWITCH_CSR_DATA).
CSR Write Auto
DATASHEET
Increment /
Decrement
Command
Write Data
Command
Register
Register
Register
Write
Read
Idle
59
is incremented or decremented accordingly, and another
Switch Fabric CSR Interface Command Register
CSR_BUSY = 1
Switch Fabric CSR Interface Data Register
CSR_BUSY = 0
CSR Write Direct
Address
for reading sequential register
Command
Register
Register
Range
Direct
Switch Fabric CSR Interface
Write
Read
Data
Idle
CSR_BUSY = 1
Revision 1.2 (04-08-08)
Switch Fabric
Switch
with