19 Integrated Touch Controller (ITC)

The Integrated Touch Controller (ITC) allows measuring capacitances of the capacitive sensors connected to CVDANx pins. The sensor’s capacitance is processed using a Capacitive Voltage Divider algorithm (CVD). The ITC does not include its own Analog to Digital conversion core and works together with ADC 5 to convert the CVD analog signal into a digital form. The Integrated Touch Controller CVD procedure is programmed in software-defined Acquisition and Post-Processing/Math sequences.

The Integrated Touch Controller has following features:

• Up to 32 Conversion Records. Each Record can be Assigned to Any CVD Analog Input.
• Up to three Conversion Lists. Each List:
  • Joints a group of the records.
  • Has a balance timer selection same for all records in the list.
  • Has a processing trigger selection to scan (process) all list records.
  • Can compare the records results with predefined thresholds (digital comparator).
  • Has a programmable data acquisition sequencer and a post-processing sequencer.
• Data Acquisition Sequencer:
  • Supports up to 16 steps/commands.
  • Controls a charge/discharge process for CVD algorithm implementation.
  • Controls CVD balance time and conversion.
  • Can drive high/low or tri-state the analog inputs and digital TX pins and CVD guards.
• Post-Processing (math) Sequencer:
  • Supports up to 16 steps/commands.
  • Can add or subtract the conversion results.
  • Has a few accumulators to store intermediate data.

A simplified block diagram of the ITC is illustrated in Figure 19-1.

The ITC has a number of records. These records can be assigned to the CVD inputs for processing. Then, the records are joined in groups called lists. Each list allows selecting the charge balance time, trigger and some other parameters. The list triggers execute the CVD procedure on the CVDANx pins defined in the list’s records.

ITC can be used for any advanced sensing applications to implement core independent automation of sensor signal sampling and processing. ITC is not restricted to only touch applications.