In the System Configuration module, you choose the Controller and Sensor that are about to be connected together and set up their Connectivity Interface.
The Controller and Sensor selection is self explanatory:
The Connectivity Interface selection defines the way those two entities will be interfaced with one another on a circuit (system) level. Here you connect the physical model of the touch sensor with the controller pins by selecting both (Ctrl+left click) a terminal of the touch sensor (left side) and a controller pin (right side). Then you click on "Add connection" (on top) and you are done.
About controller pins, you must first define their mode:
- Deactivated: the pin is connected anywhere
- Touch Sensor: the pin is connected to a terminal that leads to an active electrode of the touch panel (e.g. button/slider/wheel)
- Capacitor: the pin is connected to the sampling capacitor of a group
- Active Shield: the pin is connected to a shielding entity that is not grounded, but acts like an electrode of the touch sensor.
Every connection between a controller pin and a touch sensor terminal may also include a circuit element, such as resistor, capacitor, inductor or diode. 10 kΩ is the default resistor value, whereas it is 47 nF for the sampling capacitor.
The only exception is the Vss pin which is directly connected to the shielding of the touch sensor and no circuit element is allowed to be added. Here you may choose between two options:
- Earth Ground, which is the real ground (electric potential equals to zero)
- System Floating Ground, which is not the real earth ground, but the local "ground" of the system (COM) (electric potential different than zero). This is the most common case in touch devices.
Special focus is needed for the pins that are connected to the touch sensor, since these pins belong to Groups and Banks. The pins that belong to the same group share the same sampling capacitor, so they cannot be activated simultaneously. On the contrary, the pins that belong to the same bank are activated simultaneously. Reasonably, the pins that belong to the same group must belong to different banks.
In this section you may also choose to use Human Body Model for the pointer or not.
This is the second description of the pointer in Sense. The first one was In the "Physical" tab, where we created a Pointer and simulate its influence on the performance of a sensor, in terms of change of capacitance. However, when the netlist is extracted, the actual electrical model of the pointer is not printed, only its influence on the sensor.
This electrical model can be added in this selection, to approximate reality even more. The Human Body Model (HBM) consists of the resistance of the human body and its self capacitance and is connected to earth ground.
Common values are 1500 Ohm for the resistance and 100 pF for the self capacitance:
If you do not choose to add a Human Body Model for the pointer, then the pointer will be added in the equivalent circuit as an electrically floating conductor.
In case you need more info on how to set up the System Configuration, you can also have a look at this guide (step 7) which describes an actual case.