How to Solve Write-Verify Failures with MX25L12835FM2I-10G

How to Solve Write-Verify Failures with MX25L12835FM2I-10G

Introduction

The MX25L12835FM2I-10G is a popular 128Mb Serial Flash Memory from Macronix, typically used for applications requiring non-volatile memory. If you encounter Write-Verify Failures, it can be frustrating, but understanding the causes and systematically troubleshooting the issue can help you resolve it efficiently.

In this guide, we'll break down the potential causes of Write-Verify Failures and offer a detailed, step-by-step solution to help you solve the issue.

What is Write-Verify Failure?

A Write-Verify Failure occurs when data is written to the flash memory but, during the verification phase, the data doesn’t match what was expected. This mismatch could happen because:

The written data is corrupted. The memory cells didn’t properly store the data. The process of reading back the data after writing is inaccurate.

Potential Causes of Write-Verify Failures

1. Power Supply Issues

The flash memory requires a stable and clean power supply for proper writing and verification. Voltage fluctuations or insufficient current can cause issues during data writing, resulting in Write-Verify Failures.

Symptoms: The failure might happen randomly or in specific conditions, often during write-heavy operations. Solution: Ensure that your power supply is stable. Check the voltage levels (typically 3.3V for this memory) and current specifications. If necessary, use decoupling capacitor s near the power pins of the MX25L12835FM2I-10G. 2. Write Protection Enabled

The memory might have write protection enabled either globally or on specific blocks. When write protection is enabled, any write operation will fail.

Symptoms: Write failures might occur immediately or during specific block writes. Solution: Check the status of the WP# (Write Protect) pin. Make sure it's not tied to low, which would trigger write protection. If you're using the memory in a system with external protections, disable write protection if necessary. 3. Timing Issues

Incorrect timing between the CE# (Chip Enable), WE# (Write Enable), and OE# (Output Enable) signals can cause write and verification failures. Flash memory is sensitive to timing, and if signals are not properly synchronized, it can result in data corruption.

Symptoms: The failure may happen consistently or sporadically, especially when switching between read and write operations. Solution: Review the timing requirements in the datasheet. Ensure your system meets the timing specifications, especially the write enable and chip enable timing. 4. Incorrect Command Sequence

The MX25L12835FM2I-10G requires a specific sequence of commands to perform a write operation successfully. If there’s an error in the sequence of commands (e.g., incorrect addressing, lack of chip erase), write verification can fail.

Symptoms: Write operation fails, and you might receive error codes or indications of invalid addresses. Solution: Verify that the correct sequence is followed: Write Enable command Program command (to write the data) Write Disable command Read command for verification

Ensure that each command is properly spaced and timed.

5. Insufficient Write Time or Fast Clock Speed

Flash memories like the MX25L12835FM2I-10G need sufficient time to store data. If the clock speed of the communication interface (SPI) is too fast, the data may not be written correctly.

Symptoms: Writes might be incomplete or fail to verify correctly, especially with high-speed SPI operations. Solution: Lower the SPI clock speed and retry the operation. Ensure that the data setup time is long enough for the flash memory to properly store the data. 6. Faulty or Inadequate Memory

Although rare, a faulty memory chip or poor-quality soldering can lead to Write-Verify failures. Overheating, excessive voltage, or physical damage during manufacturing can affect the chip’s ability to store data correctly.

Symptoms: Write failures happen consistently even under ideal conditions. Solution: Test the flash memory on another system or replace it with a known-good unit to confirm if the chip is faulty.

Step-by-Step Solution

Here’s a detailed, step-by-step approach to troubleshoot and fix Write-Verify Failures with the MX25L12835FM2I-10G:

Step 1: Check Power Supply Ensure that the voltage is stable at 3.3V (or according to datasheet specifications). Use a multimeter to measure the current draw during writing to ensure it meets the required levels. Add decoupling capacitors (0.1 µF and 10 µF) near the power pins of the memory for noise suppression. Step 2: Verify Write Protection Check the WP# pin to ensure that it is not held low, which would enable write protection. If needed, toggle the WP# pin high to disable write protection. Step 3: Review Timing Parameters Refer to the datasheet for timing diagrams and ensure that all the signal timings (CE#, WE#, OE#, etc.) meet the required specifications. Ensure that the SPI clock speed is within the recommended range. Step 4: Validate Command Sequence Follow the correct sequence: Send Write Enable command. Issue the Program command with the correct address and data. Follow up with a Write Disable command. Perform a Read command to verify the written data matches what was sent. Double-check the address being written to is valid and within the proper range. Step 5: Reduce SPI Clock Speed Lower the SPI clock speed if you suspect that the memory is not receiving enough time to store the data. Gradually increase the speed to see at what rate the write operation succeeds. Step 6: Test with Another Memory Chip (If Possible) If the issue persists even after following all the steps above, it may be due to a faulty flash chip. Swap the memory chip with a known good one to confirm if the chip itself is defective.

Conclusion

Write-Verify Failures in the MX25L12835FM2I-10G can be caused by various issues, including power supply problems, write protection, incorrect timing, or faulty memory. By following the steps above, you should be able to identify and fix the root cause of the failure.

If you continue to experience issues, it’s always worth consulting the datasheet for specific details or contacting the manufacturer for further support.