MIKROE Altitude 5 Click is a compact add-on board allowing high-resolution barometric pressure measurement. This board features the KP236, an analog barometric air pressure sensor based on a capacitive principle from Infineon Technologies. The KP236 is primarily developed for measuring barometric air pressure but can also be used in other application fields. It is surface micro-machined with a monolithic integrated signal conditioning circuit implemented in BiCMOS technology. The calibrated transfer function converts pressure into an analog output signal in a range of 40kPa to 115kPa. However, the choice of signal processing is up to the user; more precisely, the user can process the output signal in analog or digital form. The high accuracy and the high sensitivity of the KP236 make this Click board™ suitable for advanced automotive applications and industrial and consumer applications.

Altitude 5 Click is supported by a mikroSDK compliant library, which includes functions that simplify software development.

Altitude 5 Click as its foundation uses the KP236, a high-resolution analog barometric air pressure sensor based on a capacitive principle from Infineon Technologies. The KP236 surface is micro-machined with a monolithic integrated signal conditioning circuit implemented in BiCMOS technology that can measure pressure in a range from 40kPa up to 115kPa with an accuracy of ±1Pa over a wide operating temperature range at the industry’s lowest power. The KP236 is primarily developed for measuring barometric air pressure but can also be used in other application fields.

The pressure is detected by an array of capacitive surface micro-machined sensor cells. The sensor cell output is amplified, temperature-compensated, and linearized to obtain an output voltage proportional to the applied pressure. The transfer function for linearization is computed in the digital part of the sensor using a third-order polynomial calculation. The sensor converts pressure into an analog output signal; more precisely, the user can process the output signal in analog or digital form.

The analog output voltage of the KP236 can be converted to a digital value using MCP3221, a successive approximation A/D converter with a 12-bit resolution from Microchip, using a 2-wire I2C compatible interface, or can be sent directly to an analog pin of the mikroBUS™ socket labeled as AN. Selection can be performed by onboard SMD jumper labeled as ADC SEL to an appropriate position marked as AN and I2C. Using MCP3221 and I2C interface, data transfers at rates of up to 100kbit/s in the Standard and 400kbit/s in the Fast Mode.

Since the sensor for operation requires a 5V logic voltage level only, this Click board™ also features the PCA9306 voltage-level translator from Texas Instruments. The I2C interface bus lines are routed to the dual bidirectional voltage-level translator, allowing this Click board™ to work with both 3.3V and 5V MCUs properly.

This Click board™ can operate with both 3.3V and 5V logic voltage levels selected via the VIO SEL jumper. This way, it is allowed for both 3.3V and 5V capable MCUs to use the communication lines properly. However, the Click board™ comes equipped with a library containing easy-to-use functions and an example code that can be used, as a reference, for further development.

• Interface: Analog, I²C
• Compatibility: mikroBUS™
• Dimensions: 42.9 x 25.4mm
• Input Voltage: 3.3V or 5V
• Ambient Operating Pressure Range: Min. 40kPa, Max. 115kPa
• Maximum Output Current: 1mA
• Accuracy: Min. -1kPa, Max. 1kPa
• Sensitivity: 53.3 mV/kPa
• Operating Temperature Range: Min. -40°C, Typ. +25°C, Max. +125°C

• Schematic
• KP236 Datasheet
• MCP3221 Datasheet
• mikroSDK
• LibStock