Capacitive sense MCU targets touch user interfaces

The microcontrollers are fully integrated mixed‑signal microcontrollers. The devices include up to 32KBytes of Flash that is programmable in 512Byte sectors, and up to 8.25KBytes RAM. A 10‑bit analogue to digital converter (ADC) can capture signals up to 300ksps.

The chips can operate with a 1.8V to 3.6V supply voltage and have seven power modes: In Active Mode, the device draws only 200µA/MHz. In the lowest power mode, Sleep Mode, the microcontroller draws as little as 55nA and can wake up on an oscillator failure, SmarRTClock timer event, or on an I2C address match.     

The Capacitive Sense unit uses a capacitive‑to‑digital circuit to determine the capacitance present on a port pin. An internal analogue multiplexor allows the unit to take measurements from different port pins. The unit can be configured to take capacitance measurements from one port pin or a group of ports pins. A selectable gain circuit allows the developer to adjust the maximum allowable capacitance. A 22‑bit accumulator is built into the capacitance sense unit, which can be configured to average multiple conversations from a single input pin.     

For security applications, each microcontroller contains a 128‑bit unique key to specifically identify each device. The C8051F97x MCUs boast an on-chip debugging interface that provides non‑intrusive, full-speed, in‑circuit debugging of the microcontroller while operational. The debugging interface uses no on‑chip resources and does not interfere with running code.     

The C8051F970 development kit is also available from Mouser Electronics. It provides a complete evaluation and development platform for C8051F97x microcontrollers. The board supports capacitive sensing applications and contains all the hardware and software needed to begin developing projects using the C8051F970 microcontroller.