On the Flying Fish module, the analog output (AO) is a voltage (Vout) from the voltage divider: Vout = Vcc * (RL / (RL + Rs))
The datasheet for the Flying Fish MQ-7 contains an error for beginners. The MQ-7 heater requires a 60-second cycle (1.5V heating, 5V low power). The standard 5V supply on the MH board will work for detection but reduces sensor lifespan. For accurate CO readings, add a MOSFET circuit to cycle the heater. Mh Mq Sensor Flying Fish Datasheet