Enable the bias voltage $\mathrm{V} _{\mathrm{BIAS} } $ and wait at least 10.5 ms before initiating the conversion. This allows any filter capacitors at the RTDIN inputs to charge before an accurate conversion can be performed[3][5].

If you are using a 3-wire RTD connection, write 1 to the 3-Wire (D4) bit in the Configuration Register. For 2-wire or 4-wire connections, write 0 to this bit[3].

To enter the manual fault detection cycle, ensure that $\mathrm{V} _{\mathrm{BIAS} } $ has been on for at least 5 time constants. Then, write $100 \times 100 \times b$ to the Configuration register. The MAX31865 checks for faults while the FORCE- input switch is closed. After the check completes, the FORCE-input switch opens. Wait at least 5 time constants, and then write 100X110Xb to the Configuration register. The MAX31865 now checks for faults while the FORCE- inputs switch is open. When the check completes, the FORCE- input switch closes and the Fault Detect Cycle bits (D[3:2]) self-clear to 00b[4].

If you want to select automatic conversion mode, write 1 to the Conversion Mode (D6) bit in the Configuration Register. If you want to exit automatic conversion mode and enter the "Normally Off" mode, write 0 to this bit. From the "Normally Off" mode, you can initiate 1-shot conversions by writing 1 to the 1-Shot (D5) bit[5][6].

If a fault is detected, you can clear all fault status bits $(D[7: 2])$ in the Fault Status Register by writing 1 to the Fault Status Clear (D1) bit. This bit self-clears to 0[8].

Finally, you can select the notch frequencies for the noise rejection filter by writing to the $50 / 60 \mathrm{~Hz} $ (D0) bit. Write 0 to this bit to reject $60 \mathrm{~Hz} $ and its harmonics; write 1 to this bit to reject $50 \mathrm{~Hz} $ and its harmonics[8].