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9 years, 1 month ago.
Not able to drive 5V for my RFID reader from FRDMK64 board
Dear All,
I'm having FRDMK64F board and want to interface RFID reader. I' powered up the board using external 5V through J24 connector and want to connect RFID reader into the board but not able to drive enough (from VIN pin) power for RFID reader (5V to 16V).
Even I've tried to use 7.5V and 12V adapter and no success. I've measured voltage between RFID reader and got 2.3V, 2.5V and 2.7V respectively when I used both 5V, 9V and 12V supply.
What could be the reason for that ?
I'm able get the exact voltage on VIN pin which I given via adapter when I didn't connect RFID reader to the board.
How can I address this hw requirement ?
As of now, I'm using 2 separate 5V adapters for both RFID reader and FRDMK64F board.
Any help appreciated.
Thanks in advance.
Regards, Titus S.
1 Answer
9 years, 1 month ago.
Vin is for supplying power in to the board not for supplying power out. There are diodes between J24 and VIN so that if you connect different power supplies to both bins you don't blow things up. (top left of page 4 of the schematic here: http://developer.mbed.org/media/uploads/sam_grove/spf-28163_d.pdf )
If you want to make the Vin pin act as a power output for whatever you supply on J24 then replace D10 with a piece of wire. If you do this then the VIN pin will always be about 0.2V below the highest of J24, the USB VBUS and the OpenSDA power supply.
However be careful in the future since connecting power supplies to both at once could cause nasty things to happen.
This i expect is a current not a voltage problem. Your supply will need a higher current output maybe 1amp or more, i don't know what both boards need.
posted by David Fletcher 21 Mar 2015Yes, I also suspect the same, so I have tried 2A rating supply and still facing the same problem.
posted by Titus Stalin 21 Mar 2015I've tried 12V/7A rating power adapter to power up the FRDMK64F board and still not able to drive RFID reader(HID iClass).
posted by Titus Stalin 21 Mar 2015Are you connecting the grounds of both boards together?
posted by David Fletcher 21 Mar 2015Yes, I did. Also able to power up the RFID reader when I use two 5V adapter for both (commonly grounded to the both adapters) .
posted by Titus Stalin 23 Mar 2015