
I
2
C interface
UM0404
DocID13284 Rev 2
I2CSR1 (EA02h)
XBUS
Reset Value: 0000h
ENGC
Enable General Call
This bit is set and cleared by software. It is also cleared by hardware when the
interface is disabled (PE
=
0). The 00h General Call address is acknowledged (01h
ignored).
‘0’: General Call disabled.
‘1’: General Call enabled.
PE
Peripheral Enable
This bit is set and cleared by software.
‘0’: Peripheral disabled
‘1’: Master/Slave capability
Notes:
– ‘0’: all the bits of the I2CCR, I2CSR1 and I2CSR2 registers except the STOP bit
are reset.
– ‘1’: the corresponding I/O pins are selected by hardware as alternate functions.
To enable the I
2
C interface, write the I2CCR register
TWICE
with PE
=
1 as the first
write only activates the interface (only PE is set).
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
–
EVF
ADD10
TRA
BUSY
BTF
ADSL
M/SL
SB
R
R
R
R
R
R
R
R
Bit
Function
SB
Start bit (Master mode)
This bit is set by hardware as soon as the Start condition is generated (following a
write START
=
1). An interrupt is generated if ITE
=
1. It is cleared by software
reading I2CSR1 register followed by writing the address byte in I2CDR register. It is
also cleared by hardware when the interface is disabled (PE
=
0).
‘0’: No Start condition.
‘1’: Start condition generated.
M/SL
Master/Slave
This bit is set by hardware as soon as the interface is in Master mode (writing
START
=
1). It is cleared by hardware after detecting a Stop condition on the bus or
a loss of arbitration (ARLO
=
1). It is also cleared when the interface is disabled
(PE
=
0).
‘0’: Slave mode
‘1’: Master mode
ADSL
Address matched (Slave mode)
This bit is set by hardware as soon as the received slave address matched with the
OAR register content or a general call is recognized. An interrupt is generated if
ITE
=
1. It is cleared by software reading I2CSR1 register or by hardware when the
interface is disabled (PE
=
0).
The SCL line is held low while ADSL
=
1.
‘0’: Address mismatched or not received.
‘1’: Received address matched.
Bit
Function