Table 29-7 I2Sr Register Description - Motorola DragonBall MC9328MX1 Reference Manual

2
I C Module
2
29.6.4 I C Status Register
2
The I C Status Register (I2SR) indicates transaction direction and status.
I2SR
BIT 31 30 29
TYPE r r r
0 0 0
RESET
BIT 15 14 13
TYPE r r r
0 0 0
RESET
Name
Reserved Reserved—These bits are reserved and should read 0.
Bits 31–8
ICF Data Transfer—Indicates data transfer condition. ICF is
Bit 7 cleared while one byte of data is transferred.
2
IAAS I C Addressed As a Slave—Indicates that the device
Bit 6 slave address matches the address sent on the data line.
2
When the I C Enable (IIEN) bit in the I2CR Register is set,
an interrupt is generated to the ARM9 core when this
match occurs. The ARM9 core must check the Slave
Read/Write (SRW) bit and set the Transmit/Receive Mode
Select (MTX) bit of the I2CR Register accordingly. Writing
to the I2CR Register clears this bit.
2
IBB I C Bus Busy—Indicates the status of the bus. When a
Bit 5 STOP signal is detected, IBB is cleared, and when a
START signal is detected, IBB is set.
IAL Arbitration Lost—Indicates that this device will not operate as bus master. IAL cleared by writing 0 to
Bit 4 it, and is set by the hardware in the following circumstances:
• SDA samples low when the master drives high during an address or data-transmit cycle
• SDA samples low when the master drives high during the acknowledge bit of a data-receive
cycle
• A START is attempted when the bus is busy
• A repeated START is requested in slave mode
• A STOP condition is detected when the master did not request it
29-12
2
I C Status Register
28 27 26 25
r r r r
0 0 0 0
12 11 10 9
r r r r
0 0 0 0
Table 29-7. I2SR Register Description
Description
MC9328MX1 Reference Manual
24 23 22 21 20
r r r r r
0 0 0 0 0
0x0000
8 7 6 5 4
ICF IAAS IBB IAL
r r r r rw
0 1 0 0 0
0x0081
0 = Transfer in progress
1 = Transfer complete (set at the falling
edge of the ninth clock of a byte
transfer)
0 = Not addressed
1 = Addressed as a slave (set when the
MC9328MX1 slave address in the
IADR Register matches the calling
address)
0 = Bus is idle
1 = Bus is busy
Addr
0x0021700C
19 18 17 16
r r r r
0 0 0 0
3 2 1 0
SRW IIF RXAK
r r rw r
0 0 0 1
Settings
MOTOROLA