I2C BUS INTERFACE
2
I C BUS INTERFACE (Cont’d)
2
Bit 0 = ITE Interrupt Enable.
I C STATUS REGISTER 1 (I2CSR1)
R241 - Read Only
The ITE bit enables the generation of interrupts.
This bit is set and cleared by software and cleared
by hardware when the interface is disabled
(I2CCR.PE=0).
0: Interrupts disabled (reset value)
1: Interrupts enabled after any of the following con-
ditions:
Register Page: 20 (I2C_0) or 22 (I2C_1)
Reset Value: 0000 0000 (00h)
7
0
EVF ADD10 TRA
BUSY BTF ADSL M/SL
SB
– Byte received or to be transmitted
(I2CSR1.BTF and I2CSR1.EVF flags = 1)
Note: Some bits of this register are reset by a read
operation of the register. Care must be taken when
using instructions that work on single bit. Some of
them perform a read of all the bits of the register
before modifying or testing the wanted bit. So oth-
er bits of the register could be affected by the op-
eration.
In the same way, the test/compare operations per-
form a read operation.
Moreover, if some interrupt events occur while the
register is read, the corresponding flags are set,
and correctly read, but if the read operation resets
the flags, no interrupt request occurs.
– Address matched in Slave mode while
I2CCR.ACK=1
(I2CSR1.ADSL and I2CSR1.EVF flags = 1)
– Start condition generated
(I2CSR1.SB and I2CSR1.EVF flags = 1)
– No acknowledge received after byte transmis-
sion
(I2CSR2.AF and I2CSR1.EVF flags = 1)
– Stop detected in Slave mode
(I2CSR2.STOPF and I2CSR1.EVF flags = 1)
– Arbitration lost in Master mode
(I2CSR2.ARLO and I2CSR1.EVF flags = 1)
– Bus error, Start or Stop condition detected
during data transfer
Bit 7 = EVF Event Flag.
This bit is set by hardware as soon as an event (
listed below or described in Figure 128) occurs. It
is cleared by software when all event conditions
that set the flag are cleared. It is also cleared by
hardware when the interface is disabled
(I2CCR.PE=0).
(I2CSR2.BERR and I2CSR1.EVF flags = 1)
– Master has sent header byte
(I2CSR1.ADD10 and I2CSR1.EVF flags = 1)
– Address byte successfully transmitted in Mas-
ter mode.
(I2CSR1.EVF = 1 and I2CSR2.ADDTX = 1)
0: No event
1: One of the following events has occurred:
SCL is held low when the ADDTX flag of the
I2CSR2 register or the ADD10, SB, BTF or ADSL
flags of I2CSR1 register are set (See Figure 128)
or when the DMA is not complete.
The transfer is suspended in all cases except
when the BTF bit is set and the DMA is enabled. In
this case the event routine must suspend the DMA
transfer if it is required.
– Byte received or to be transmitted
(I2CSR1.BTF and I2CSR1.EVF flags = 1)
– Address matched in Slave mode while
I2CCR.ACK=1
(I2CSR1.ADSL and I2CSR1.EVF flags = 1)
– Start condition generated
(I2CSR1.SB and I2CSR1.EVF flags = 1)
– No acknowledge received after byte transmis-
sion
(I2CSR2.AF and I2CSR1.EVF flags = 1)
– Stop detected in Slave mode
(I2CSR2.STOPF and I2CSR1.EVF flags = 1)
– Arbitration lost in Master mode
(I2CSR2.ARLO and I2CSR1.EVF flags = 1)
– Bus error, Start or Stop condition detected
during data transfer
(I2CSR2.BERR and I2CSR1.EVF flags = 1)
– Master has sent header byte
(I2CSR1.ADD10 and I2CSR1.EVF flags = 1)
273/426
9
STMICROELECTRONICS [ ST ]
