About the value of MB_MODE of ST25DV64K at power-on

MMoro.4 · ‎2021-06-30

Hello all

I use ST25DV64K.

I am always set the MB_MODE of ST25DV64K to 1 after power-on

After setting the value to 1, a verify check is performed to confirm that the value is set to 1.

And the result MB_MODE is 1.

When the power is turned on again after the above operation, MB_MODE is always set to 0.

Since MB_MODE is the "System configuration area", I thought MB_MODE is 1, but MB_MODE is 0.

Is this the correct behavior of the ST25DV?

Also, is there an explanation of this behavior in the datasheet (st25dv64.pdf)?

BR

Morooka

JL. Lebon · ‎2021-07-08

Hello Morooka,

The MB_CTRL_Dyn register is a volatile regsiter, and will always be set to 0 at boot time.

The MB_MODE is a static configuration register that is non-volatile, and value is kept upon reboot.

Now, the MB_MODE is not linked to the value of MB_EN bit in MB_CTRL_Dyn register.

Here is how it works:

If MB_MODE=0, it is forbidden to write in MB_CTRL_Dyn register.

If MB_MODE=1, it is allowed to write in MB_CTRL_Dyn register.

MB_CTRL_Dyn is used to enable the mailbox (so called Fast Transfer Mode), on demand during a session, by writing the MB_EN bit to 1.

By default, the device always boots with mailbox disabled, meaning MB_EN=0 in MB_CTRL_Dyn register.

So, if you want to use the mailbox after boot, you have to explicitly write MB_EN=1 in MB_CTRL_Dyn.

Hope this is more clear now.

Best regards.

MMoro.4 · ‎2021-07-04

I'm sorry.

The register is not MB_MODE, but MB_EN(bit0) of MB_CTRL_Dyn register.

So, will the MB_EN bit of the MB_CTRL_Dyn register be set to "0" when the power is turned on?

Even if the MB_MODE register is '1', will the MB_EN bit in the MB_CTRL_Dyn register remain '0'?

BR