Tag Archives: AT42QT Touch IC

Designing an advanced glucose meter with AVR MCUs

A glucose meter can best be described as a portable battery powered medical device used to measure blood glucose concentration on test strips.


Glucose meters are typically equipped with a display and mass storage solution, with certain models featuring an IrDA or a USB interface to export data to a computer. Unsurprisingly, there is currently an emerging trend for glucose meters to be equipped with Bluetooth or BTLE capabilities, thereby facilitating easy connection to mobile devices such as smartphones and tablets.

Key design considerations for a glucose meter include ultra low power consumption, high system integration (high-end analog peripherals), low BOM cost and versatile connectivity options for bio-sensors, display, buzzer, memory and PCs.

As illustrated in the diagram above, Atmel’s versatile AVR portfolio can be used to help engineers design an advanced glucose meter using the ATxmega256A3BU 8/16bit low power AVR-based MCU, AT86RF231/232/233 RF Transceiver, AT42QT Touch IC and ATSHA204 Authentication IC with EEPROM.

“Simply put, Atmel’s ATxmega256A3BU¬†offers ultra low power consumption, high integration, compact package and connectivity features to address the key needs of a glucose meter,” an Atmel engineering rep told Bits & Pieces.

“In terms of ultra low power requirements, our ATxmega256A3BU¬†supports 1.62-3.6V and boasts 5 flexible sleep modes. In Power Save mode (RTC running), the current consumption is below 1uA, while in Active Mode, the current consumption is 350uA/MHz at 1.8V. Meanwhile, a DMA Controller handles data transfer between the peripherals and memory.”

On the connectivity side, Atmel offers a full speed compliant USB device port with embedded PHY to save BOM cost (~$0.5-$1.0). As expected, the port can be used for battery charging and data transfer to a PC. Atmel also offers integrated UART, USART, SPI and I2C – allowing easy connection to external sensors, memories and display.

“It should also be noted that Atmel-powered glucose meters require a minimum in terms of external (additional) hardware, thanks to integrated RTC, high performance ADC and DAC, PLL and voltage reference,” said the engineering rep.

“And last, but certainly not least, Atmel’s AVR MCUs benefit from our extensive software ecosystem, such as Atmel Studio and free software libraries of production ready source code including ZigBee PRO Software (BitCloud), Proprietary Low Footprint, 802.15.4 Mesh Software Stack, USB Stack and QTouch Library.”