Intel PXA255 manual 4 I2C Status Register ISR, ICR Bit Definitions Sheet 3, Receive mode

Models: PXA255

1 600
Download 600 pages 33.14 Kb
Page 355
Image 355

I2C Bus Interface Unit

Table 9-10. ICR Bit Definitions (Sheet 3 of 3)

 

 

 

Physical Address

 

 

 

 

I2C Control Register

 

 

 

 

 

I2C Bus Interface Unit

 

 

 

 

 

 

 

4030_1690

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Bit

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

31

30

29

28

27

26

25

24

23

22

21

20

19

18

17

16

15

14

13

12

11

10

9

8

7

6

5

4

3

 

2

1

0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

reserved

 

 

 

 

 

 

FM

UR

SADIE

ALDIE

SSDIE

BEIE

IRFIE

ITEIE

GCD

IUE

SCLE

MA

TB

 

ACKNAK

STOP

START

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Reset

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

 

0

0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ACK/NAK Control: defines the type of ACK pulse sent by the I2C unit when in master-

 

 

 

 

 

 

 

 

 

 

receive mode.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2

 

 

ACKNAK

0 = The I2C unit sends an ACK pulse after it receives a data byte.

 

 

 

 

 

 

 

 

 

 

 

1 = The I2C unit sends a negative ACK (NAK) after it receives a data byte.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The I2C unit automatically sends an ACK pulse when it responds to its slave address or

 

 

 

 

 

 

 

 

 

 

when it responds in slave-receive mode, independent of the ACK/NAK control bit setting.

 

 

 

 

 

 

 

 

 

STOP: initiates a STOP condition after the next data byte on the I2C bus is transferred in

 

 

 

 

 

 

 

 

 

master mode. In master-receive mode, the ACK/NAK control bit must be set along with this

 

 

1

 

 

 

STOP

 

bit. See Section 9.3.3.3 for more details on the STOP state.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0 = Do not send a STOP.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1 = Send a STOP.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

START: initiates a START condition to the I2C unit when in master mode. See

 

 

 

 

 

0

 

 

 

START

 

Section 9.3.3.1 for more details on the START state.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0 = Do not send a START.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1 = Send a START.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

9.9.4I2C Status Register (ISR)

The ISR, shown in Table 9-11, signals I2C interrupts to the processor interrupt controller. Software can use the ISR bits to check the status of the I2C unit and bus. ISR bits (bits 9-5) are updated after the ACK/NAK bit is completed on the I2C bus.

The ISR also clears the following interrupts signalled from the I2C unit:

IDBR Receive Full

IDBR Transmit Empty

Slave Address Detected

Bus Error Detected

STOP Condition Detect

Arbitration Lost

This is a read/write register. Ignore reads from reserved bits. Write zeros to reserved bits.

Intel® PXA255 Processor Developer’s Manual

9-25

Page 355
Image 355
Intel PXA255 manual 4 I2C Status Register ISR, ICR Bit Definitions Sheet 3, Receive mode