I2C Bus Interface Unit

Figure 9-11. Master-Transmitter Write to Slave-Receiver

START Slave Address

R/nW

0

ACK

Data Byte

ACK

Data Byte

ACK STOP

 

 

First Byte

 

Write

N Bytes + ACK

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Master to Slave

Slave to Master

 

Figure 9-12. Master-Receiver Read to Slave-Transmitter

START

Slave Address

R/nW

ACK

Data

ACK

Data

NAK

STOP

1

Byte

Byte

 

 

 

 

 

 

 

 

First Byte

 

Read

 

 

N Bytes + ACK

 

 

 

 

 

 

Default

 

 

 

 

 

 

 

 

Slave-Receive

 

 

 

 

 

 

 

 

 

Mode

 

 

 

 

 

Master to Slave

Slave to Master

 

 

 

 

 

 

Figure 9-13. Master-Receiver Read to Slave-Transmitter, Repeated START, Master-Transmitter Write to Slave-Receiver

Slave

R/nW

 

Data

 

Data

 

Slave

R/nW

 

Data

 

Data

 

START Address

1

ACK

Byte

ACK

Byte

ACK SR

Address

0

ACK

Byte

ACK

Byte

ACK STOP

 

Read

 

N Bytes + ACK

Repeated

Write

 

N Bytes + ACK

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

START

 

 

 

 

 

 

 

 

 

 

 

 

 

Data Chaining

 

 

 

 

 

 

Master to Slave

Slave to Master

 

 

 

 

 

 

 

 

 

 

9.4.8General Call Address

A general call address is a transaction with a slave address of 0x00. When a device requires the data from a general call address, it acknowledges the transaction and stays in slave-receiver mode. Otherwise, the device ignores the general call address. The other bytes in a general call transaction are acknowledged by every device that uses it on the bus. Devices that do not use these bytes must not send an ACK. The meaning of a general call address is defined in the second byte sent by the master-transmitter. Figure 9-14shows a general call address transaction. The least significant bit of the second byte, called B, defines the transaction. Table 9-7shows the valid values and definitions when B=0.

9-16

Intel® PXA255 Processor Developer’s Manual

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Intel PXA255 manual General Call Address, ACK Stop, NAK Stop