Peak EMI Reducing Solution

7 of 11

rev 1.3

February 2005

ASM3P2508A

I2C Serial Interface Information

The information in this section assumes familiarity with I2C programming.

How to program ASM3P2508A through I2C:

•

Master (host) sends a start bit.

•

Master (host) sends the write address D4 (H).

•

ASM3P2508A device will acknowledge.

•

Master (host) sends the beginning byte location

(N = 0, 1).

•

ASM3P2508A device will acknowledge.

•

Master (host) sends a byte count (X = 1,2)

•

ASM3P2508A device will acknowledge.

•

Master (host) starts sending byte N through byte

(N+X – 1)

•

ASM3P2508A device will acknowledge each byte one

at a time.

•

Master (host) sends a Stop bit.

Controller (Host)

ASM3P2508A

(slave/receiver)

Start Bit

Slave Address D4(H)

ACK

Beginning byte location (=N)

ACK

Byte count (=X)

ACK

Beginning byte (Byte N)

ACK

Next Byte (Byte N+1)

ACK

-------

----

Last Byte (Byte N+X-1)

ACK

Stop Bit

How to Read from ASM3P2508A through I2C:

•

Master (host) will send start bit.

•

Master (host) sends the write address D4 (H).

•

ASM3P2508A device will acknowledge.

•

Master (host) sends the beginning byte location

(N = 0, 1).

•

ASM3P2508A device will acknowledge.

•

Master (host) will send a separate start bit.

•

Master (host) sends the read address D5 (H).

•

ASM3P2508A device will acknowledge.

•

ASM3P2508A device will send the byte count

(X = 1, 2).

•

Master (host) acknowledges.

•

ASM3P2508A device sends byte N through byte

(N+X – 1).

•

Master (host) will need to acknowledge each byte.

•

Master (host) will send a stop bit.

Controller (Host)

ASM3P2508A

(slave/receiver)

Start Bit

Slave Address D4(H)

ACK

Beginning Byte = N

ACK

Repeat start

Slave address D5(H)

ACK

Byte Count (= X)

ACK

Beginning byte N

ACK

Next Byte N+1

ACK

----

-------

Last Byte (Byte N+X-1)

Not Acknowledge

Stop Bit