Contactless gesture recognition speaks volumes on Click
MikroElektronika (Mikroe) has a compact add-on board that provides contactless gesture recognition to its Click series.
The IR Gesture 3 Click board is based on Analog Devices’ ADPD1080, a multi-function photometric front-end device that features a fully integrated AFE, ADC, LED drivers, and timing core. The core enables ambient light rejection capability without photodiode optical filters. The drivers can deliver 370mA of peak current for LED, with flexible, multiple, and short LED pulses per optical sample. Its 14-bit ADC and 20-bit burst accumulator enable up to 20 bits per sample period, with sampling frequency ranging from 0.122Hz to 2700Hz.
The ADPD1080 operates as a complete optical transceiver stimulating the SFH4249, a high power, infrared emitter from ams Osram, which acts as a 940nm light source that works with a short switching time. The front-end IC measures the return in the analogue block through the separate current inputs, storing the results in discrete data locations. This data can be read by the host microcontroller. The ADPD1080 has a 1.8V analogue/digital core, the BH18PB1WHFV, a CMOS LDO regulator from Rohm Semiconductor.
The ADPD1080 uses the ADPD2140, an infrared light angle sensor from Analog Devices as current inputs. The silicone P-type, intrinsic, N-type photodiode provides a linear measurement of incident infrared light angle in four separate channels. The two-axis light angle measurement is available in both x and y directions, where the resulting quantities are ratios related to angles through a constant term. The ADPD1080 front-end is connected with the ADPD2140 angle sensor via its four photodiode current inputs and a common photodiode cathode bias. The photodiode current inputs get analogue data over the ADPD2140 analogue outputs.
In state machine operation, the ADPD1080 can operate in standby, program, and normal modes. The normal mode follows a specific pattern set up by a state machine, consisting of LED pulse and sample, intersample averaging, data read and repeat. The LED pulse and sample pattern allow each data sample to be constructed from the user-configurable sum of pulses (1-255). The intersample averaging pattern samples in an average of two to 128 samples in powers of two.
All Click boards are based on Mikroe’s mikroBUS modular prototyping add-on board standard. This allows design engineers to change peripherals easily, cutting months off development time. Any Click board can be connected to the microcontroller or microprocessor on a main board. Many leading microcontroller companies including Microchip, NXP, Infineon, Dialog, STM, Analog Devices, Renesas and Toshiba now include the mikroBUS socket on their development boards.