Intel® PXA255 Processor Developer’s Manual
9-27
I
2
C Bus Interface Unit
9.9.5
I
2
C Slave Address Register (ISAR)
The ISAR, shown in
Table 9-12
, defines the I
2
C unit’s 7-bit slave address. In slave-receive mode,
the processor responds when the 7-bit address matches the value in this register. The processor
writes this register before it enables I
2
C operations. The ISAR is fully programmable (no address is
assigned to the I
2
C unit) so it can be set to a value other than those of hard-wired I
2
C slave
peripherals in the system. If the processor is reset, the ISAR is not affected. The ISAR register
default value is 0000000
2
.
This is a read/write register. Ignore reads from reserved bits. Write zeros to reserved bits.
1
ACKNAK
ACK/NAK Status
:
0 = I
2
C unit received or sent an ACK on the bus.
1 = I
2
C unit received or sent a NAK.
Used in slave-transmit mode to determine when the transferred byte is the last one.
Updated after each byte and ACK/NAK information is received.
0
RWM
Read/Write Mode
:
0 = I
2
C unit is in master-transmit or slave-receive mode.
1 = I
2
C unit is in master-receive or slave-transmit mode.
R/nW bit of the slave address. Automatically cleared by hardware after a stop state.
Table 9-11. ISR Bit Definitions (Sheet 2 of 2)
Physical Address
4030_1698
I
2
C Status Register
I
2
C Bus Interface Unit
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
BE
D
SA
D
GCA
D
IR
F
ITE
AL
D
SS
D
IB
B
UB
A
CKN
AK
RW
M
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
0
Table 9-12. ISAR Bit Definitions
Physical Address
4030_16A0
I
2
C Slave Address Register
I
2
C Bus Interface Unit
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
ISA
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
0
31:7
—
reserved
6:0
ISA
I
2
C Slave Address
: 7-bit address that the I
2
C unit responds to when in slave-receive
mode.
Содержание PXA255
Страница 1: ...Intel PXA255 Processor Developer s Manual January 2004 Order Number 278693 002 ...
Страница 24: ...xxiv Intel PXA255 Processor Developer s Manual Contents ...
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Страница 310: ...7 46 Intel PXA255 Processor Developer s Manual LCD Controller ...
Страница 330: ...8 20 Intel PXA255 Processor Developer s Manual Synchronous Serial Port Controller ...
Страница 358: ...9 28 Intel PXA255 Processor Developer s Manual I2 C Bus Interface Unit ...
Страница 488: ...13 36 Intel PXA255 Processor Developer s Manual AC 97 Controller Unit ...
Страница 572: ...16 30 Intel PXA255 Processor Developer s Manual Network SSP Serial Port ...
Страница 599: ...Intel PXA255 Processor Developer s Manual 17 27 Hardware UART ...
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