the tx-rx inputs of the module uses 3.3 volt so a 2k and 1k resistor is used to decrease the voltage from 5v to 3.33
however i have 2.2k and 1k resistor that ll decrease the voltage to 3.43v.
is it safe to use these resistors instead of the 2k and 1k resistors?
2x1K resistors in series will get you 2k Ohm. So if you have 3x1k resistors you are good.
An it probably does not make that much difference. All the resistors are +/- a percentage, depending on the resistor, so the values are never exact.
With that sort of serial resistance you may be getting problems in sourcing/sinking enough current. Remember also there is inherent input capacitance, so your signal will be compromised.
Is there a reason you don't want to use an inexpensive level shifter?