Issue with Reading Back Values on VNF1048F IC

[AnuSabu]

I'm having trouble when reading back the values I have written to the VNF1048F IC.Every time, the unused bit is being enabled, Even after only performing the software reset,the unused bit is setting.Here's what I have tried so far:
1.Performed a software reset.
2.Set the Unlock bit and write unlock bit threes times in control register3
3.Set the watchdog trogger to 1 and the watchdog time to 200ms.
4.Enabled the EN bit.
5.Configured the threshold values.
Despite these steps,when i read back,only the unused bit is being set, and no other bits are enabling.Can you please help me to identify what might be going wrong?

[Andrew Neil]

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@AnuSabu wrote:

Every time, the unused bit is being enabled, ?

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What "unused bit" ?

If it is unused, does its value matter?

What does the datasheet say about this bit?

Hardware registers aren't just memory - they don't necessarily read-back what was previously written.

Often, "unused" bits will read-back the same value irrespective of what was previously written.

Again, the datasheet should make this clear...

[AnuSabu]

Hi Andrew,

The datasheet states that unused bits will always be read as 0 in write mode, read mode, read and clear status commands. I haven't set any unused bits to 1, but I'm still reading them as 1. Are there any hidden bits that need to be enabled for proper writing and reading of values, apart from these steps I've already tried?

[Andrew Neil]

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@AnuSabu wrote:

I haven't set any unused bits to 1, but I'm still reading them as 1.

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How, exactly, are you reading them?

Have you used an oscilloscope and/or logic analyser on the wires to check if that's what's actually coming from the chip?

[Tesla DeLorean]

No one here is familiar with your software and hardware implementation.

Describe your platform, your SPI interactions, show you can read the ROM constants out successfully.

Perhaps work with your local ST rep, FAE or distributor?

Open an online support request  https://ols.st.com/s/