This page shows a snapshot of the whole S-Touch family. There are twelve-channel and eight-channel devices in-stock with five and nine channel devices available on request. There is also a three channel device available. All devices in the S-Touch family share some common features: dynamic range, individually adjustable touch setting, auto-calibration, data filtering, I2C bus, etc. There are also some important differences. For example, the basic twelve-channel has twelve channels dedicated to the touch sensing inputs, plus another twelve as GPIO (General Purpose I/O). This can be an advantage in the case that there is not enough GPIO's in the microcontroller being used as the host controller. Therefore, the STMP1208 can be used not only as a touch sensing controller, but also as a port expander, adding extra I/O. The more sophisticated twelve channel is the 1218 comes with twelve indicated touch sensing channels plus twelve GPIOs, but it also has a four channel PWM, allowing more flexibility in giving visual feedback to the user. For example, rather than just turning on and off an LED with a GPIO, the four channel PWM allows fade in/fade out effects. The other devices, the 921, 821, 521 and the 321, are very similar. They have a single GPIO bank with each GPIO capable of being assigned to a sensing input or GPIO, but they do not have an additional, separate GPIO-only bank. The nine, eight, and five channel devices have the four channel PWM. The three channel device is the most basic of all with three sensor channels and no separate bank of GPIOs and no PWM.