A few days ago I started playing with some idea I had from a few weeks already, using a Raspberry Pi Zero W to make a mini WiFi deauthenticator: something in my pocket that periodically jumps on all the channels in the WiFi spectrum, collects information about the nearby access points and their connected clients and then sends a deauthentication packet to each one of them, resulting in some sort of WiFi jammer on the 802.11 level. As an interesting “side effect” of this jammer (the initial intent was purely for the lulz) is that the more it deauths, the higher the changes to also sniff WPA2 handshakes.
Murata produces LoRa module CMWX1ZZABZ-xxx based on SX1276 transceiver and STM32L072CZ microcontroller. The soldering of the LGA module is not very hobby-friendly. I constructed small breakout PCB for this module with additional buck/boost switcher and place for SMA connector. The transceiver features the LoRa®long-range modem, providing ultra-long-range spread spectrum communication and high interference immunity, minimizing current consumption. Since CMWX1ZZABZ-091 is an “open” module, it is possible to access all STM32L072 peripherals such as ADC, 16-bit timer, LP-UART, I2C, SPI and USB 2.0 FS (supporting BCD and LPM), which are not used internally by SX1276.
I came across a very useful post by Thomas Scherrer that describes how to read data from a Peacefair PZEM-021 energy meter by spying on the SPI bus with an Arduino. I decided to do the same thing with an ESP-12F WiFi module so that I could view the results remotely and plot graphs, etc. It took me a lot longer to get this working than I anticipated due to a few problems along the way.
The main hardware difference is the ESP8266 is a 3.3V device but the Arduino is 5V. The PZEM-021 is actually a mixture. The RN8208G metering chip is a 5V device. It is a SPI slave, the SPI master is an STM32 ARM processor that is 3.3V but with 5V tolerant inputs.
Rui Santos writes, “In this project, you’re going to learn how to control the ESP8266 or the ESP32 with voice commands using Alexa (Amazon Echo Dot). As an example, we’ll control two 12V lamps connected to a relay module. We’ll also add two 433 MHz RF wall panel switches to physically control the lamps.”
I have been working on some games for the ESP32 and needed some decent quality audio with a minimum number of additional components. I was bouncing between using the DAC and using the I2S bus. The DAC requires less external parts, so I went that way. I ended up creating a very simple library for use in he Arduino IDE. (Note: This only works with ESP32)