Hi,
I have an Arduino Nano and a nRF24L01+ 2.4GHz RF chip that works with 3.3volt, its a KAP (Kite Aerial Photography) project so it must be as light as possible. For testing and prototyping I used the nano plugged to the usb port, but now I will use a 9v battery.
But i have read that if you don't power arduino with the USB, the FTDI chip doesn´t work and the 3.3v pin neither, so if I use an external regulator (5V) and plug it to the USB port then I will also have 3.3v? or the best way is plugging the 9V directly to pin 30 and use an external regulator for the 3.3v RF chip?
Thanks!
But i have read that if you don't power arduino with the USB, the FTDI chip doesn´t work and the 3.3v pin neither,
The schematic does not support that - if the voltage source is Vin, than 5v is created by the onboard regulator, and the FTDI chip is powered. USB power is only available if Vusb is greater then the output of the 5V regulator.
This is from the Arduino Nano specifications:
As a result, when running on external (non-USB) power, the 3.3V output (which is supplied by the FTDI chip) is not available and the RX and TX LEDs will flicker if digital pins 0 or 1 are high.
I understand that if I don't power from the USB, only from de Vin the 3.3V output is useless.
Again not correct. If the AVR chip is powered (by whatever means avalible) so is the FTDI chip, and the 3.3vdc regulator is internal inside the FTDI chip, so 3.3vdc is also avalible. However be cautious using 3.3vdc for and circuitry you add as it's limited to around 40 ma and can destroy the FTDI chip if you attempt to draw too much 3.3v current.
ok, thanks for the answers!
So best way powering the arduino with the unregulated input (9Volt) and then I'll make a 3.3 voltage regulator for the RF chip.
LucasKenda:
ok, thanks for the answers!
So best way powering the arduino with the unregulated input (9Volt) and then I'll make a 3.3 voltage regulator for the RF chip.
Well as I said if your RF chips only needs 40ma or less of 3.3volts current you can power it from the Nano's 3.3 pin.
But in 2.4G NRF24L01+PA+LNA specs says:
Transmit mode current (peak):115mA
So is better to use an external power 