Load Volatile and Read Volatile Configuration Register commands in HyperFlash - KBA232852
Question: What is the difference between the "Load Volatile Configuration Register" command and the "Read Volatile Configuration Register" command in HyperFlash?
Answer: In HyperFlash, the Load Volatile Configuration Register command is used to update the contents in Volatile Configuration Register (VCR), whereas the Read Volatile Configuration Register command is used to read out the VCR contents.
HyperFlash contains two copies of the Configuration Register: Nonvolatile Configuration Register (NVCR) and Volatile Configuration Register (VCR).
The HyperFlash device uses the contents of the NVCR to define bus characteristics upon power-up or after a Hardware Reset. If the host system loads the VCR (by sending Load Volatile Configuration Register command), the configuration in VCR will take effect. Once the VCR is loaded, only a power-up or Hard Reset will reload the NVCR settings to take effect. However, if the NVCR settings are needed without a power-up or Hard Reset, the Load Volatile Configuration Register command can be used to update VCR settings to the same value as NVCR. The NVCR is intended to hold a default setting to align with the host controller settings during boot operation. The VCR is often updated with optimized settings during/after the boot process, or for setting temporary configuration values.