Forehead thermometer reference design


The design of a forehead thermometer encompasses a microcontroller with ADC, vitality administration and connectivity for healthcare functions.


NXP Semiconductor’s reference design for a forehead thermometer is based on the K32L2B microcontroller. It is a refined decision designed for cost-sensitive, low-power battery-powered functions. This design amenities spherical a 48MHz ARM Cortex-M0+ core and helps 256K flash memory, making it extremely efficient however surroundings pleasant. The MCU assortment stands out for its rich combination of analog peripherals and digital interfaces, explicitly aimed towards functions the place minimizing worth and vitality utilization is important.

One in all many key choices of this design is its built-in 16-bit multi-channel ADC (analog to digital converter). This ADC is important for gathering indicators from the infrared temperature sensor and measuring the battery voltage. The precision ranges of the MCU’s ADC are pretty extreme, reaching 13.9 bits in single-ended mode and 14.5 bits in differential mode. This precision permits the thermometer to realize a robust temperature measurement accuracy of 0.1 ranges.

The design moreover includes a 12-bit DAC (digital to analog converter), which affords bias voltage to exterior op amps. This DAC eliminates the need for an exterior stage conversion chip and should present a 1.2V reference voltage with a 1mA load performance. Furthermore, the design incorporates a low-power SLCD (Part LCD) present, which helps 24×8 or 28×4 segments. SLCD pins are versatile and efficiency as frequent and section ports or for various IO options.

Connectivity on this design is improved by the inclusion of three I2C channels. These channels are configured so that one connects to a digital infrared sensor or proximity sensor, one different to a extreme precision digital temperature sensor such as a result of the PCT2075 and the third, using FlexIO, might be configured for conventional I2C, UART communications or SPI. . Furthermore, the design makes use of PWM (pulse width modulation) to handle LED indicators or audible alarms and should assist voice playback options.

One different highlight is the USB interface, which includes a USB FS 2.0 gadget interface that works with out further glass. In relation to memory and vitality effectivity, the K32L2B11VLH0A ​​​​variant with 64K flash and 32K RAM could be very applicable for forehead thermometers. It choices low vitality consumption in working and deep sleep modes and has a fast wake mode of decrease than 10 microseconds.

The 64K flash functionality adequately meets storage requirements for calibration parameters, voice info, and additional. The MCU assortment moreover provides quite a lot of product roadmaps, supporting full pin operate assist and the selection in order so as to add new choices much like Bluetooth and QR code scanning.

The design includes a built-in ROM bootloader, immensely useful for on-line updates and calibration of temperature parameters. The high-precision built-in interior clock is essential for manufacturing unit firmware manufacturing.

NXP Semiconductor has examined this reference design. Comes with a bill of provides (BOM), schematics, and plenty of others. Additional info on the reference design might be found on the company’s website online. To study further about this reference design, Click on on proper right here.