Section 10.3.7 Mode Select Pins
Mode Select pins (M1, M2 & M3) Should be connected to either VREG (for logic high) or AGND for logic low. It is not recommended to connect pins to board ground if 1-Ohm resistor is used between AGND and GND.
Question:- Can one tie M1 directly to +3.3V, instead of using a pull-up resistor?