Peripheral Simulation

For Silicon Laboratories, Inc. C8051F125 — SMBus0 / I²C Interface

Simulation support for this peripheral or feature is comprised of:

• Dialog boxes which display and allow you to change peripheral configuration.
• VTREGs (Virtual Target Registers) which support I/O with the peripheral.

These simulation capabilities are described below.

SMBus0 Interface - Communications Dialog

The System Management Bus 0 Communication Dialog allows you to view the data sent or received on the SMBus0.

I²C Message Generator

• Address contains address of the sending or receiving device.
• Direction selects the direction of the message to be sent or received.
• Bytes is the length of the last message in bytes.
• Data is the message data sent or received.
• Generate starts message transmission.
• Stop suspends I²C bus communication.

SMBus0 Interface - Hardware Dialog

The System Management Bus 0 Interface Dialog allows you to view and edit the SMBus0 simulator configuration. The SMBus0 is compatible with the I²C serial bus. Simulation of this interface is controlled by the following groups:

Control

• SMB0CN (SMBus0 Control Register) contains the following bits that control the functions of the SMBus0:
• BUSY (Busy Status Flag) is set when the SMBus0 is busy.
• ENSMB (SMBus Enable) is set when the SMBus0 is enabled.
• STA (SMBus Start Flag) is set when the SMBus0 has started a transmission as a master.
• STO (SMBus Stop Flag) is set to send a stop condition on the SMBus.
• SI (SMBus Serial Interrupt Flag) is set to trigger a SMBus0 interrupt.
• AA (SMBus Assert Acknowledge Flag) is set to request that an acknowledge be returned during the acknowledge cycle.
• FTE (SMBus Free Timer Enable Bit) is set to timeout when SCL high time exceeds limit specified by the SMB0CR value.
• TOE (SMBus Timeout Enable Bit) is set to enable the SMBus0 timeout.

Clock

• SMB0CR (SMBus0 Clock Rate Register) controls the frequency of the serial clock SCL in master mode.
• I2C Master Clock is the master clock calculated from the system clock and the SMB0CR value.

Status

• SMB0STA (SMBus0 Status Register) contains the 8-bit status code.
• Device Mode displays the state of the SMBus0 controller.
• Status a text description of the status code.

Address

• SMB0ADR (SMBus0 Address Register) contains the following values:
• Slave Address (SMBus0 Address Register) contains the slave address of the SMBus0 interface.
• GC (General Call) is set when the general call address is recognized.

Data

• SMB0DAT (SMB0 Data Register) contains the either the data to be transmitted or the data just received.

SMB0_CLK VTREG
Data Type: unsigned long

The SMB0_CLK VTREG specifies the clock frequency (in Hz) to use in SLAVE mode. 100000 specifies 100KHz.

SMB0_IN VTREG
Data Type: unsigned int

The SMB0_IN VTREG contains data sent from an SMBus0 or I²C peripheral to the simulated MCU.

• 0x0000-0x00FF: An address or data byte transfer.
• 0x0100: START byte. This initiates a SLAVE transmit or receive. The next byte sent is the address.
• 0xFF00: ACK.
• 0xFF01: NACK.
• 0xFFFF: IDLE or STOP condition.

SMB0_OUT VTREG
Data Type: unsigned int

The SMB0_OUT VTREG contains data sent from the simulated MCU to an SMBus0 or I²C peripheral.

• 0x0000-0x00FF: An address or data byte transfer.
• 0x0100: START byte. This initiates a MASTER transmit or receive. The next byte sent is the address.
• 0xFF00: ACK.
• 0xFF01: NACK.
• 0xFFFF: IDLE or STOP condition.