ESP8266 PIR Motion Detector

This project connects a PIR motion detector to an ESP8266 but it is especially battery efficient because the ESP8266 is turned off when motion is not present.

  • Adafruit Huzzah ESP8266 board
  • Adafruit PIR motion sensor
  • Batteries, 3xAA

Battery PIR     ESP8266 Huzzah
======= ===     ==============
POS --- 3-5V -- VBAT
NEG --- GND --- GND
        DOUT -- LDO cut pull up
The PIR maximum voltage is 5V. Four batteries produces 6V which is too high.

There is a pull up resistor on the LDO enable pin which is required when nothing is connected to LDO. In this case, the PIR DOUT signal is connected to the LDO pin so the pull up is not needed. To get maximum battery life, the resistor must be disconnected to prevent it from wasting power. In the following photo, the red line shows the trace to cut.


LDO is the enable pin for the 3.3V voltage regulator (VR). When grounded, it turns off the VR so everything on the 3.3V side is powered off. When the PIR does not detect motion, it drives DOUT low so the ESP8266 board is powered off. When the PIR detects motion, it drives DOUT high which turns on the ESP8266.

The PIR Time potentiometer determines how long the DOUT is high so set it to the maximum which is about 7 seconds on my PIR. On the PIR, set the Retrigger Setting Jumper set to the SW1 H position.

The sketch must connect to the AP and send a motion detected message (MQTT or HTTP or something else) as soon as possible. After it is done, the sketch should put the ESP8266 is deep sleep. DOUT could be high for as long as motion is present. Use deep sleep to save power until motion stops and DOUT goes low turning the ESP8266 off.

Comments

Post a Comment

Popular posts from this blog

Defective Arduino USB Host Shield Boards

Image
UPDATE: The red wire is not needed. There are solder pads to the right of the reset button. Bridge the 5V pads to select 5V for VBUS PWR. In total, three blobs of solder are needed to make the shield work for 5V Arduinos. I received two new generic Arduino compatible USB host shields today. Both are defective. But they work after some troubleshooting. 1. After loading the USB_desc sketch, the debug message "OSC did not start." appears on the serial console. This means the USB host library cannot find the USB host hardware. I compared a defective board with a working board. One big difference is the 3.3V pads and 5V pads are not bridged on the defective board. This means the shield is not receiving power from the Uno! After bridging the pads, the board powers up. The error message "OSC did not start" does not appear. This means the USB host library found the USB host hardware. In the photo, the green boxes should contain one big solder blob. If there are
Read more

How to use USB RFID readers on an Arduino Uno

Image
1. Plug the RFID reader into a Windows PC. Does it work without installing drivers? Open any editor such as NotePad. Read a card or key fob by passing the card or key fob on or near the reader. Do the characters appear on the screen as if typed at a keyboard? Look in Device Manager. The reader should be listed as a USB keyboard. If all the above are true, it should work with a USB host shield and Uno running the USB HID keyboard sketch. The same procedure applies to bar code readers. Do not expect all USB RFID and bar code readers to work like USB keyboards. Some devices such as RFID reader/writers require special USB drivers so are not usable with the USB host shield. The simple RFID readers shown above, read the RFID unique serial number. No other fields are returned. The readers cannot write to the RFID card. In the photo, starting at the top, are a 125KHz RFID reader, a 13.56 MHz RFID reader, Arduino Uno, and Circuits@Home USB host shield. Both readers work with the USB
Read more

WeMos D1 R2 ESP8266 with USB Host Shield

Image
WiFi-enable a wide variety of USB devices using an ESP8266 and a USB host shield. For example, add a WiFi interface to a USB barcode reader or a USB RFID keyfob reader. The USB Host for Arduino driver  project has added support for ESP8266 so here are some of my experiments. For more details, see the demos on github.com. A modified USB Host Shield is plugged into a WeMos D1 R2 ESP8266 board. A USB host mini board fits on top of an Adafruit ESP8266 Feather. This configuration turns a $16 USB barcode scanner into a battery powered WiFi barcode scanner.
Read more