© 2009 Microchip Technology, Inc.

DS41393A-Page 21

7.15.4 Register Read - 0x20

Read a value from a controller register location. This can be used to determine a controller configuration setting.

Configuration registers are defined as an Offset value from the Start address for the register group. Read a

register as follows.

1) Issue the <Register Start Address Request> command to obtain the Start address for the register group.

2) Calculate the desired register’s absolute address by adding the register’s Offset value to Start address for the

register group.

3) Issue this <Register Read> command, as follows, using the calculated register’s absolute address

Send

: <0x55><0x04><0x20><Register Address High byte><Register Address Low byte><# of Registers to Read>

# of Registers to Read

: 0x01 thru 0x08

Register Address High byte

: 0x00

Receive : <0x55><0x02 + # of Registers Read><Response><0x20><Register value>…<Register value>

7.15.5 Register Write - 0x21

Write a value to a controller register location. This can be used to change a controller configuration setting.

Configuration registers are defined as an Offset value from the Start address for the register group. Write a

register as follows.

1) Issue the <Register Start Address Request> command to obtain the Start address for the register group.

2) Calculate the desired register’s absolute address by adding the register’s Offset value to Start address for the

register group.

3) Issue this <Register Write> command, as follows, using the calculated register’s absolute address

Send: <0x55><0x04 + # Registers to Write><0x21><Register Address High byte><Register Address Low byte>

<# of Registers to Write><Data>…<Data>

# of Registers to Write

: 0x01 thru 0x08

Register Address High byte

: 0x00

Receive : <0x55><0x02><Response><0x21>

7.15.6 Register Start Address Request - 0x22

Configuration registers are defined as an Offset value from the Start address for the register group. This

command returns the Start address for the register group.

Send

: <0x55><0x01><0x22>

Receive : <0x55><0x03><Response><0x22><Register Start Address>

7.15.7 Registers Write to EEPROM - 0x23

Save Configuration Register values to EEPROM. This allows the controller to remember configurations settings

through controller power cycles.

Send

: <0x55><0x01><0x23>

Receive : <0x55><0x02><Response><0x23>