STLC1502 View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
'STLC1502' PDF : 81 Pages View PDF
STLC1502
By default, it operates in slave mode. The interface automatically switches from slave to master after it
generates a START condition and from master to slave in case of arbitration loss or a STOP generation,
allowing then Multi-Master capability.
In Master mode, it initiates a data transfer and generates the clock signal. A serial data transfer always
begins with a start condition and ends with a stop condition. Both start and stop conditions are generated
in master mode by software.
In Slave mode, the interface is capable of recognizing its own address (7 or 10 bits), and the General Call
address. The General Call address detection may be enabled or disabled by software.
Data and addresses are transferred as 8-bit bytes, MSB first. The first byte(s) following the start condition
contain the address (one in 7-bit mode, two in 10-bit mode). The address is always transmitted in Master
mode. A 9th clock pulse follows the 8 clock cycles of a byte transfer, during which the receiver must send
an acknowledge bit to the transmitter.
• Acknowledge may be enabled and disabled by software. The I 2 C interface address and/or general
call address can be selected by software. The speed of the I 2 C interface may be selected between
Standard (0-100KHz) and Fast I2C (100-400KHz).
• In transmitter mode the interface holds the clock in low before transmission to wait for the microcon-
troller to write the byte in the Data Register.
• In receiver mode: the interface holds the clock line low after reception to wait for the microcontroller
to read the byte in the Data Register.
• The SCL frequency (Fscl) is controlled by a programmable clock divider which depends on the I 2 C
bus mode.
• When the I2C cell is enabled, the SDA and SCL ports must be configured as floating inputs. In this
case, the value of the external pull-up resistor used depends on the application.
7.6.3 Functional Description
Refer to the CR, SR1 and SR2 registers in register map section for the bit definitions.
By default the I 2 C interface operates in Slave mode (M/SL bit is cleared) except when it initiates a trans-
mit or receive sequence. First the interface frequency must be configured using the FRi bits in the OAR2
register.
7.6.3.1 Slave mode
As soon as a start condition is detected, the address is received from the SDA line and sent to the shift
register; then it is compared with the address of the interface or the General Call address (if selected by
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