LAN9500AI datasheet(83/213 Pages) MICROCHIP

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DS00001875A-page 83

LAN950x

If the EEPROM operation is the “write location” (WRITE) or “write all” (WRAL) commands, the Host must first write the

desired data into the E2P_DATA register. The Host must then issue the WRITE or WRAL command using the E2P_CMD

must also be set to the desired location. The command is executed when the Host sets the EPC_BSY bit high. The

completion of the operation is indicated when the EPC_BSY bit is cleared.

If the EEPROM operation is the “read location” (READ) operation, the Host must issue the READ command using the

E2P_CMD register with the EPC_ADDR set to the desired location. The command is executed when the Host sets the

EPC_BSY bit high. The completion of the operation is indicated when the EPC_BSY bit is cleared, at which time the

data from the EEPROM may be read from the E2P_DATA register.

Other EEPROM operations are performed by writing the appropriate command to the E2P_CMD register. The command

is executed when the Host sets the EPC_BSY bit high. The completion of the operation is indicated when the EPC_BSY

bit is cleared. In all cases, the Host must wait for EPC_BSY to clear before modifying the E2P_CMD register.

If an operation is attempted, and an EEPROM device does not respond within 30mS, the device will timeout, and the

EPC Time-out bit (EPC_TO) in the E2P_CMD register will be set.

Figure 5-20 illustrates the Host accesses required to perform an EEPROM Read or Write operation.

Note:

The EEPROM device powers-up in the erase/write disabled state. To modify the contents of the EEPROM,

the Host must first issue the EWEN command.

FIGURE 5-20:

EEPROM ACCESS FLOW DIAGRAM

Idle

Write Data

Write

Command

Read

Command

Idle

Write

Command

Read

Command

Read Data

Busy Bit = 0

EEPROM Write

EEPROM Read

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