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UART and arduino uno communication

I have a nRF51822 and arduino uno board. Is it possible to connect my nRF51822 uart to the arduino rx/tx, so that i can use it for communication to PC through arduino. The voltage levels in UNO works on 5V p-p and nRF51822 is 3.3 p-p. Will it destroy the nRF51822 if we connect the pins?

  • Hi

    The absolute maximum ratings chapter in the nRF51822 PS specifies maximum voltage on GPIO pins to be VDD+0.3V (nRF51 supply voltage + 0.3V), so it is allowed to have your UART peer device to drive the UART with up to 3.9V if your supply voltage to the nRF51822 is at maximum at 3.6V.

    Section 8.23 in the PS specifies the voltage levels required for GPIO pins, i.e. that input high voltage is detected at VDD0.7 and input low voltage is detected at VDD0.3. So if your supply voltage to the nRF51is 3.3V, then the UART peer device must operate between 3.3*0.7=2.31V and 3.3+0.3=3.6V

    So, if your arduino has 5V output on UART then you would need a voltage-level shifter circuit to enable the UART communication with nRF51822.

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