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At the electrical level, the protocol used for single-ended mode looks a lot like I²C or 1-wire with the lines being pulled normally-high. You could bit-bang this protocol or (if you need better performance) you could use the microcontroller's FLEXIO functionality. As shown in the INLC10AQ datasheet starting from page 12, the protocol for single-ended mode is as follows:

• The microcontroller holds the SIO_N line high¹ to indicate single-ended mode then writes output bits to the SIO_P line by driving the line low. The signal is self-clocking. This is shown on page 12 of the datasheet:
  

• When done sending the microntroller switches its IO pins to be inputs and the SIO_P and SIO_N lines are pulled high by the pull-up resistors. To send a response, the peripheral chips drive the SIO_P line low to indicate 0 bits while at the same time providing a clock signal by driving SIO_N low. This is shown on page 14:
  

For single-ended operation the V_IL,SE and V_IH,SE are given on page 8 of the datasheet:

Since the parameters are from the perspective of the peripheral chip (the INLC10AQ) they are given as input voltages, not output voltages (i.e. as V_IL,SE and V_IH,SE rather than V_OL,SE and V_OL,SE). On the microcontroller end you'll need to bring the voltage down to 1.04V or lower to send a 0 bit or pull it up to between 1.08V and 5.5V² to send a 1 bit. Likewise, the peripheral INLC10AQ will connect a line to GND to indicate a 0 or leave it pulled high to indicate a 1 (the peripheral never actively drives a line high; it goes high-impedance to indicate a 1). The datasheet doesn't recommend a particular value for the pull-up resistors³ but 4.7kΩ would be a good starting point.

In a nutshell, the INLC10AQ uses a proprietary communications protocol whose electrical characteristics are described above. The low and high input and output voltages are the same as those used by the microcontroller. Typically these voltages are 0V for a 0 and 5V for a 1 though a lower signalling voltage (e.g. 3.3V or 1.8V) can be used for the latter. No V_OH or V_OL values are given in the datasheet because the line voltages are provided at the microcontroller end (VDD via pull-up and ground, respectively), not by the INLC10AQ.

¹ Ideally, the microcontroller should leave SIO_N high-impedance (i.e. as an input). The pull-up resistor will ensure that the line is normally high.

² The datasheet lists 5.5V as the maximum recommended high voltage (VCC5); 7V is the absolute maximum.

³ There should be two pull-up resistors: one between SIO_P and the microcontroller's VDD line and the other between SIO_N and VDD.