WREN 12S SDK V2 – Connections

Last Updated OnJanuary 6, 2023

byDave Williams

Provisional Page

The WREN 12S SDK V2 connections have been designed to try and be relatively straight forward and intuitive. However this page has been created to help with the basics of bring up.

First is to connect a USB UART to the WREN 12S SDK in order to be able to upload and develop new firmware. This is done via the UART port, both of which are paralleled up so either can be used.

You could connect just the TXD, RXD and Ground, then hold the PGM button to place into programming mode, upon power up. Alternatively, by connecting the RTS and DTR connections to the USB UART, the flashing process will be simpler, as this removes the need to put the SDK into programming or flashing mode.

Note: Remember to cross over the TXD and RXD! Also do NOT connect the 5V!

Wiring from WREN to the UART is as per:

WREN TXD to UART RXD
WREN RXD to UART TXD
WREN DTR to UART DTR
WREN RTS to UART RTS
WREN GND to UART GND

You can connect the WREN 3V3 to the UART 3V3 for flashing.

UART (Flashing the firmware)

1 +3V3
2 RXD
3 TXD
4 DTR (Used to place in auto flash mode)
5 RTS (Used to place in auto flash mode)
6 GND

Flashing

WREN 12S SDK can be flashed using your preferred development IDE, such as Arduino IDE, Visual Studio Code with Platform IO etc. You can also use Home Automation firmware flashing tools such as Tasmotizer.

When using Arduino IDE, you will also need to ensure you:

Include the ESP8266 by adding additional boards manager (preferences), include URL https://arduino.esp8266.com/stable/package_esp8266com_index.json
References to Supporting Libraries (Add to Managed Libraries)
- MCP9808 Precision I2C Temperature Sensor – Adafruit_MCP9808
  - https://learn.adafruit.com/adafruit-mcp9808-precision-i2c-temperature-sensor-guide
- MCP23017 I2c Port Expander – Adafruit_MCP23017 (USE Version 1.3.0)
  - https://github.com/adafruit/Adafruit-MCP23017-Arduino-Library

Example using the WREN 12S SDK bring up code.