How to turn a home thermostat into a smart device: easing the connectivity challenge: Page 4 of 7

May 09, 2017 //By Vikram Ramanna
Consumers are developing a taste for smart home devices, thanks in part to the new sophistication of voice-controlled technologies such as Apple’s Siri Remote and the Alexa Voice Service on Amazon Echo, and of systems for the remote control of home devices such as Google’s Nest products.

All of the elements are rigorously tested and verified, so that users can be sure that, for instance, the WICED HAP code will function perfectly when running within a ThreadX software environment on a CYW43907, a Wi-Fi IC which includes an ARM Cortex-R4 core.

The WICED platform supports various hardware architectures, giving users the choice of whether to implement WICED in a dedicated module with on-board MCU, in a fully integrated RF microcontroller, or in an external host processor (see figure 3). Microcontrollers supported by the SDK include:

  • Cypress FM4 series;
  • STMicroelectronics STM32F2 and STM32F4 series;
  • Microchip AT91SAM4S16B;
  • NXP Semiconductors Kinetis K61 and LPC17xx, LPC18xx series.

Figure 3: the hardware architectures supported by the WICED platform.

Smart thermostat: the WICED development process

A good starting point would be to connect a temperature sensor, relay and WICED module together. Figure 4 shows a set-up consisting of a temperature sensor with an I2C interface connected to the CYW43907AEVAL1F, an evaluation board featuring the Murata LBWA1UZ1GC-958 module based on the CYW43907 Wi-Fi system-on-chip, together with a small display to show the system status and temperature.

The driver written for the temperature sensor can be placed in the libraries folder of the WICED SDK, allowing other applications to use it. This same folder also contains the display driver supported in the SDK.

Figure 4: initial hardware configuration for a new smart thermostat design project.

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