18.05.2016, 21:37 by Mare

I got samples of Si7013.

The Si7013 I2C Humidity and 2-Zone Temperature Sensor is a monolithic CMOS IC integrating humidity and temperature sensor elements, an analog-to-digital

converter, signal processing, calibration data, and an I2C Interface. The patented use of industry-standard, low-K polymeric dielectrics for sensing humidity enables the construction of low-power, monolithic CMOS Sensor ICs with low drift and hysteresis, and excellent long term stability. The humidity and temperature sensors are factory-calibrated and the calibration data is stored in the on-chip non-volatile memory. This ensures that the sensors are fully interchangeable, with no recalibration or software changes required. An auxiliary sensor input with power management can be tied directly to an external thermistor network or other voltage-output sensor. On-board logic performs calibration/linearization of the external input using user-programmable coefficients. The least-significant bit of the Si7013’s I2C address is programmable, allowing two devices to share the same bus. The Si7013 is available in a 3×3 mm DFN package and is reflow solderable. The

optional factory-installed cover offers a low profile, convenient means of protecting the sensor during assembly (e.g., reflow soldering) and throughout the life of the product, excluding liquids (hydrophobic/oleophobic) and particulates. The Si7013 offers an accurate, low-power, factory-calibrated digital solution ideal for measuring humidity, dew-point, and temperature, in applications ranging from HVAC/R and asset tracking to industrial and consumer platforms.

I prepared prototyping board with STM32F0 and line RS485 driver:

Next, I populated the PCB with the components:

The sensor schematic is from Si7013 datasheet, typical application:

The microcontroller pinout is:

The microcontroller UART has hardware support for DE in RS-485 Half Duplex interface, which is nice feature for reliable RS485 operation.

Finally, I prepared driver for Si7013. I put the code to GitHUB, because it will hopefully evolve to some usable final application. First “alpha” testing provide reading and writing of “user registers” for chip configuration and readout of the humidity, temperature and external thermistor voltage.

si7013 driver: https://github.com/s54mtb/Si7013

And some preliminary testing: