Sonoff Basic with MCP23017 I2C

Hardware
1

Hi, I am working on something where I have a Sonoff Basic in the Ceiling rose controlling my lights, I02 for light switch. I want to add a MCP23017 I2C Serial Interface to expand the GPIO’s as I want to add the below to have one unit that meets all my needs:

HC-SR501 Human Sensor
GY-BME280 Temperature Humidity Sensor
GY-302 BH1750 Light Intensity Illumination Sensor

I have watched a suggested video (https://www.youtube.com/watch?v=VixBNNKykIg&t=343s), I have flashed my Basic with the ‘tasmota_6307_1m_i2c_sensors.bin’ firmware, attached the 3.3v, gnd, GPIO to I2C SDA and GPIO3 to IC2 SCL and set that also in Module Parameters. Is a pull-up required, if so where?
At this point I am unsure of what to connect where in terms of the 3 sensors (Ultimately I want Home Assistant to control and use them, but for now it would be nice the the Basic to at least see them working).
Any help would be appreciated.
Many thanks,

2

I know this post is a few months old already, I hope you have got your project going already. If not, I am a little familiar with the MCP23017 IC since I use one for my doors/windows sensors. I am not familiar with using it with the sonoff devices but as far as I know there is a library for it written already.
Also, the MCP23017 does have internal pull up resistors that you need to enable by writing to address 0x0C for port A pins or address 0x0D for port B pins.