Target mode

Configure the exerciser to act as an I2C target device responding to controller commands.

Overview

Target mode allows the exerciser to simulate an I2C target device. The device responds to transactions initiated by external controllers.

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Available functions

Target mode includes the same functions as Controller mode, except:

• Timing Settings - Not available (controller sets timing)
• Scan External Node - Not available (only controllers scan)

For descriptions of available functions, see:

• Assign - Upload topology to device
• Reload - Refresh topology from device
• Decode Settings - Configure signal decoding

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Wizard interface

In Target mode, the I2C wizard interface is displayed but all packet sending functions are disabled.

Why: Target devices respond to controller commands; they do not initiate transactions. The wizard is disabled because:

• Targets cannot send unsolicited data
• Targets only respond when addressed by a controller
• Bus protocol requires controller to initiate all transactions

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Target behavior

Responding to transactions

The target device automatically responds to:

• Address match: ACKs when its address is called
• READ requests: Sends data from internal registers
• WRITE requests: Stores data to internal registers

Internal node configuration

Even in Target mode, you can add internal nodes to simulate multiple target devices on the bus.

See: Add Internal Node

Use cases:

• Simulate multiple sensors on one bus
• Test controller multi-device handling
• Create complex test scenarios

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Testing with Target mode

Setup for testing

1. Configure target address and register behavior
2. Add internal nodes if simulating multiple devices
3. Connect external controller (or use another exerciser as controller)
4. Start Logic Analyzer or Protocol Analyzer capture
5. External controller sends transactions
6. Verify target responses in captured data

Common test scenarios

Controller development:

• Connect your controller under test
• Exerciser acts as target device
• Verify controller sends correct commands
• Check timing and protocol compliance

System integration:

• Simulate missing devices
• Test with partial hardware
• Verify bus operation with multiple targets

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Limitations in Target mode

• Cannot initiate transactions (controller-only function)
• Cannot send packets using wizard
• Cannot set bus timing (follows controller timing)
• Cannot scan for devices (controller-only function)

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Tips and best practices

Register configuration

• Configure internal registers to match the device you're simulating
• Use appropriate sub-address behavior (increment, repeat, etc.)
• Pre-load register data if testing specific read sequences

Address selection

• Choose addresses that don't conflict with other devices on the bus
• Use standard address range (0x08-0x77) unless testing reserved addresses
• Document which addresses are used for each test scenario

Verification

• Always capture transactions during testing
• Verify ACK/NACK behavior is correct
• Check data integrity in read/write operations
• Confirm timing meets I2C specification