ST72651AR6
110/161
Doc ID 7215 Rev 4
IC SINGLE MASTER BUS INTERFACE (Cont’d)
11.7.7 Register Description
I2C CONTROL REGISTER (CR)
Read / Write
Reset Value: 0000 0000 (00h)
Bit 7:6 = Reserved. Forced to 0 by hardware.
Bit 5 = PE Peripheral enable.
This bit is set and cleared by software.
0: Peripheral disabled
1: Master capability
Notes:
– When PE=0, all the bits of the CR register and
the SR register except the Stop bit are reset. All
outputs are released while PE=0
– When PE=1, the corresponding I/O pins are se-
lected by hardware as alternate functions.
– To enable the I2C interface, write the CR register
TWICE with PE=1 as the first write only activates
the interface (only PE is set).
Bit 4 = Reserved. Forced to 0 by hardware.
Bit 3 = START Generation of a Start condition.
This bit is set and cleared by software. It is also
cleared by hardware when the interface is disa-
bled (PE=0) or when the Start condition is sent
(with interrupt generation if ITE=1).
– In master mode:
0: No start generation
1: Repeated start generation
– In idle mode:
0: No start generation
1: Start generation when the bus is free
Bit 2 = ACK Acknowledge enable.
This bit is set and cleared by software. It is also
cleared by hardware when the interface is disa-
bled (PE=0).
0: No acknowledge returned
1: Acknowledge returned after a data byte is re-
ceived
Bit 1 = STOP Generation of a Stop condition.
This bit is set and cleared by software.
Note: This bit is not cleared when the interface is
disabled (PE=0).
– In Master mode only:
0: No stop generation
1: Stop generation after the current byte transfer
or after the current Start condition is sent.
Bit 0 = ITE Interrupt enable.
This bit is set and cleared by software and cleared
by hardware when the interface is disabled
(PE=0).
0: Interrupts disabled
1: Interrupts enabled
Refer to
Figure 65 for the relationship between the
events and the interrupt.
SCL is held low when the SB or BTF flags or an
70
0
PE
0
START
ACK
STOP
ITE