LAN9730 datasheet(90/222 Pages) MICROCHIP

90 / 222 page

LAN9730/LAN9730i

DS00001946A-page 90

 2012-2015 Microchip Technology Inc.

4.7.4

EEPROM HOST OPERATIONS

After the EEPROM controller has finished reading (or attempting to read) the EEPROM after a system-level reset, the

host is free to perform other EEPROM operations. EEPROM operations are performed using the EEPROM Command

(E2P_CMD) and EEPROM Data (E2P_DATA) registers. Section 6.3.12, "EEPROM Command Register (E2P_CMD)"

provides an explanation of the supported EEPROM operations.

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 com-

pletion 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 30 ms, the device will time-out, and the

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

Figure 4-20 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 4-20:

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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