SCLA021A September   2019  – April 2021 SN74HC00 , SN74HCS08-Q1

 

  1.   Trademarks
  2. 1Block Diagram
  3. 2Optimizing Communication with Wireless Interfaces
    1. 2.1 SDIO Voltage Translation
    2. 2.2 SPI Voltage Translation
  4. 3Logic and Translation Use Cases
    1. 3.1 Logic Use Cases
      1. 3.1.1 Drive Indicator LEDs
      2. 3.1.2 Power Sequencing: Combine Power-Good Signals
      3. 3.1.3 Debounce Switches and Buttons
      4. 3.1.4 Latching Alarm Circuit with Reset
      5. 3.1.5 Buffer and Driver: Condition Digital Signals
    2. 3.2 Voltage Translation Use Cases
      1. 3.2.1 SPI Communication
      2. 3.2.2 GPIO Communication
      3. 3.2.3 I2C Communication
      4. 3.2.4 I2S Communication
  5. 4Recommended Logic and Translation Families for Smart Thermostats
    1. 4.1 AUP: Advanced Ultra-Low-Power CMOS Logic and Translation
    2. 4.2 AXC: Advanced eXtremely Low-Voltage CMOS Translation
    3. 4.3 LVC: Low-Voltage CMOS Logic and Translation
  6. 5Revision History

2 Optimizing Communication with Wireless Interfaces

It is extremely common for smart thermostats to utilize wireless interfaces such as Wi-Fi™, ZigBee™, or Bluetooth™ to connect to a local network. In many designs, the simplest method to achieve this is to utilize pre-built and pre-approved modules. These modules often have limited voltage operation ranges, and to support their usage, voltage-level shifters are typically required between the extremely low power processor, often operating as low as 1.2 V, and the wireless module, commonly operating at 3.3 V.

The most common communication protocols used between the processor and wireless interface are SDIO and UART. Each is addressed specifically in the following sections.