C8051F02X Datasheet, PDF (193/272 Pages) Silicon Laboratories – 8K ISP FLASH MCU Family

C8051F020/1/2/3
18.4.3. Data Register
The SMBus0 Data register SMB0DAT holds a byte of serial data to be transmitted or one that has just been received.
Software can read or write to this register while the SI flag is set to logic 1; software should not attempt to access the
SMB0DAT register when the SMBus is enabled and the SI flag is cleared to logic 0 since the hardware may be in the
process of shifting a byte of data in or out of the register.
Data in SMB0DAT is always shifted out MSB first. After a byte has been received, the first bit of received data is
located at the MSB of SMB0DAT. While data is being shifted out, data on the bus is simultaneously being shifted in.
Therefore, SMB0DAT always contains the last data byte present on the bus. In the event of lost arbitration, the transi-
tion from master transmitter to slave receiver is made with the correct data in SMB0DAT.
Figure 18.10. SMB0DAT: SMBus0 Data Register
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0 SFR Address:
0xC2
Bits7-0:
SMB0DAT: SMBus0 Data.
The SMB0DAT register contains a byte of data to be transmitted on the SMBus0 serial interface or a
byte that has just been received on the SMBus0 serial interface. The CPU can read from or write to
this register whenever the SI serial interrupt flag (SMB0CN.3) is set to logic 1. When the SI flag is
not set, the system may be in the process of shifting data in/out and the CPU should not attempt to
access this register.
18.4.4. Address Register
The SMB0ADR Address register holds the slave address for the SMBus0 interface. In slave mode, the seven most-
significant bits hold the 7-bit slave address. The least significant bit (Bit0) is used to enable the recognition of the
general call address (0x00). If Bit0 is set to logic 1, the general call address will be recognized. Otherwise, the general
call address is ignored. The contents of this register are ignored when SMBus0 is operating in master mode.
Figure 18.11. SMB0ADR: SMBus0 Address Register
R/W
SLV6
Bit7
R/W
SLV5
Bit6
R/W
SLV4
Bit5
R/W
SLV3
Bit4
R/W
SLV2
Bit3
R/W
SLV1
Bit2
R/W
SLV0
Bit1
R/W
Reset Value
GC 00000000
Bit0 SFR Address:
0xC3
Bits7-1:
SLV6-SLV0: SMBus0 Slave Address.
These bits are loaded with the 7-bit slave address to which SMBus0 will respond when operating as a
slave transmitter or slave receiver. SLV6 is the most significant bit of the address and corresponds to
the first bit of the address byte received.
Bit0:
GC: General Call Address Enable.
This bit is used to enable general call address (0x00) recognition.
0: General call address is ignored.
1: General call address is recognized.
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