nrf uart data transmition /receving gps/gsm data

[jd3841]

hi
i am trying to communicate with two devices throught UART , in nrf51 device uart i get a voltage of 2.83 v with .0238 milli ampere while in gsm module uart pin i have 4.0 V so will it be give any issue while making a communication , will it shortcircuiting my device if i am connecting with each other

[MartinBL]

Hi,

As mtsunstrum said, you cannot connect 4 or 5 V signals directly to the nRF51. 

You might be able to connect the nRF51's UART TX pin directly to your GSMs RX pin, but it is not certain that it will work. You cannot however, connect the nRF51's RX pin to the the GSM's TX pin. Then you risk burning up your nRF51. So yes, you will most likely need some sort of voltage level shifter. You can read more about it here. 

[jd3841]

I HAVE FOUND THIS FROM MY DATA SHEET SO SHOULD I USE A  LEVEL SHIFTER OR NOT

[MartinBL]

Yes, you should use a level shifter. 

[jd3841]

thank you martinBL