Hi Chun,
I understand that you are experiencing an issue where an I2C scan through the Arduino IDE detects devices at addresses 0x01, 0x05, and 0x15, but a scan using MATLAB's 'scanI2CBus' function only detects the device at address 0x15. The user seeks an explanation for the discrepancy in detection between the two methods.
The discrepancy you're observing between the I2C addresses recognized by the Arduino IDE's scanner sketch and MATLAB's 'scanI2CBus' function can be due to a few reasons. Understanding these can help you troubleshoot and potentially resolve the issue. Here are some points to consider:
1. I2C Pull-up Resistors:
The presence or absence of pull-up resistors on the I2C lines (SDA and SCL) can affect the detection of devices on the bus. Sometimes, devices are more forgiving about the electrical characteristics of the bus when scanned using one method versus another. Ensure that your setup includes appropriate pull-up resistors (typically 4.7kΩ to 10kΩ) for stable operation.
2. Scan Range Differences:
The Arduino scanner sketch might be scanning the entire range of possible I2C addresses (0x01 to 0x7F), whereas MATLAB's 'scanI2CBus' might have a different default range or behavior. Check the documentation for 'scanI2CBus' to see if you can specify the range of addresses to scan.
3. Timing Issues:
The timing of I2C transactions can sometimes affect device recognition. This might not be directly controllable through MATLAB, but it's worth noting that differences in how the Arduino IDE code and MATLAB interface with the bus can lead to discrepancies.
4. Power Supply Issues:
Ensure that all devices on the I2C bus are properly powered and that there are no power supply issues. Insufficient power or noisy power supplies can lead to intermittent detection of I2C devices.
5. MATLAB Support Package for Arduino:
Ensure that you're using the latest version of the MATLAB Support Package for Arduino. Sometimes, bugs or limitations in earlier versions can affect functionality like I2C scanning.
6. Device Compatibility:
Some I2C devices have specific requirements (e.g., repeated start conditions) that might not be fully supported by all scanning implementations. Check the datasheets for your devices to see if there are any special considerations.
Troubleshooting Steps:
- Update your MATLAB and its Arduino Support Package to the latest version to ensure you have the latest fixes and improvements.
- Manually specify the scan range in 'scanI2CBus' if possible, to ensure it matches the range you're interested in.
- Check electrical connections and ensure that pull-up resistors are correctly installed on the I2C bus.
- Try different power supplies or power configurations to rule out power-related issues.
- Read the documentation for the devices at addresses 0x01 and 0x05 to see if they have any special requirements for communication.
Please refer to the MATLAB following Documentation to know more about MATLAB Support Package for Arduino Hardware:
Please refer to the following MATLAB Documentation to know more about scanI2CBus function:
