Disable RF communication

otmar · ‎2014-06-17

Posted on June 17, 2014 at 11:27

Hi

I'm using the M24LR04 in Harvesting Mode to supply an STM32L151.

When the uC powers up, it reads data from an sensor and write them to the M24LR.

This is than read from an NFC Handheld.

My problem is, when the Handheld approaches, first the M24LR starts to communicate with the handheld, before the uC powers up and refreshes the Data.

So i want to disable the RF communication until the STM is on.

I know there is the M24SR devices which had the RF disable Pin, but unfortunately my App is ISO15693 (and not

ISO 14443)....

Is there another possibility...

Thanx

regards

otmar

#vout #rf-wip-busy #m24lr #m24lr

Anais GALLIGANI · ‎2014-07-07

Posted on July 07, 2014 at 10:05

Hi,

What you can try to do is:

-

Let the Vout pin unconnected

-

Connect RF WIP/busy to a forward bias direction diode D1

-

And AC1 to a forward bias direction diode D2

-

D1,D2 connected to the same point, then to a resistance to a point A

-

Point A

link a capacitance to the ground
Connected to your micro

-

And the VCC is connected to an I/O of the Micro in order to be driven

-

And VCC+ DSA+SCL, all connected to your sensor.

Awaiting your feedback,

Best Regards,

ST NFC/RFID Dynamic tag support

View solution in original post

Anais GALLIGANI · ‎2014-07-07

Posted on July 07, 2014 at 10:05

Hi,

What you can try to do is:

-

Let the Vout pin unconnected

-

Connect RF WIP/busy to a forward bias direction diode D1

-

And AC1 to a forward bias direction diode D2

-

D1,D2 connected to the same point, then to a resistance to a point A

-

Point A

link a capacitance to the ground
Connected to your micro

-

And the VCC is connected to an I/O of the Micro in order to be driven

-

And VCC+ DSA+SCL, all connected to your sensor.

Awaiting your feedback,

Best Regards,

ST NFC/RFID Dynamic tag support

otmar · ‎2014-07-10

Posted on July 10, 2014 at 15:08

Hello

Thanks for your reply

Please can you check the attachment, so i don't misunderstood your circuit

best regards

otmar

________________

Attachments :

M24LRx_disable.pdf : https://st--c.eu10.content.force.com/sfc/dist/version/download/?oid=00Db0000000YtG6&ids=0680X000006HtzA&d=%2Fa%2F0X0000000aaw%2FfJRKtYgUsYr.PFv84RtCr4LtstTq_txHRRNGXpWFId8&asPdf=false

Anais GALLIGANI · ‎2014-08-29

Posted on August 29, 2014 at 10:40

Hello,

I dont see your attachment file?!

Thanks,

Have a nice day,

ST NFC RFID dynamic tags support

GCari.2 · ‎2021-01-19

Hi,

I'm facing the same problem discussed by @otmar but I didn't really understand Galligani's answer. Microcontroller is powered by energy harvesting Vout pin, so I can't leave it unnnected. Any ideas?

Regards