PMW3901 speed


I’ve looked at a few site and datasheets for the PMW3901 and found that the speed is listed as 7.4 rad/s. Why is rotational speed specified? I want to know the max X/Y speed for the PMW3901. Other optical flow sensors list the max IPS (inches per second). For example, the ADNS-3080 has max 40 IPS. Does anyone know the max IPS for the PMW3901?

Hi @finallyfunctional ,

because the sensor measures a flow rate, which is in rad/s. The maximum horizontal speed depends on the distance to the moving surface (e.g.: ground). So if you are at 1m, the maximum speed is 1x7.4 = 7.4m/s and if you are at 10m altitude, the maximum speed is 10x7.4 = 74m/s.

The ADNS-3080 is supposed to be in an optical mouse so it makes sense that they already converted the flow rate into IPS or m/s for some “typical” distance. Note that the value also depends on the optical lens used on the sensor.