Use OF A Field Effect Transistor (FET): Field effect transistor (FET) Q1 is used to reflect the voltage state of the switch’s Normally Open (N.O.) circuit which is fed to the Rx input pin of the ESP-01 module. When switch S1 changes state again, the whole process is repeated by again sending a reset signal to the module. Meanwhile, since capacitor C1 is no longer connected to a current source it slowly discharges to zero volts through resistor R2. This 0 to 3 volt rise is seen at the RESET pin of the ESP-01 Wi-Fi module and is interpreted as a reset signal which causes the module to wake up. As C2 begins to charge, the voltage across C2 slowly increases from 0 volts to 3 volts in about 0.5 seconds (RC time constant = 0.22 seconds). When switch S1 is toggled to the Normally Open (N.O.) position a positive current is applied to capacitor C2 through R1. With the switch in this position capacitor C2 is essentially an open circuit causing any charge in C2 to discharge to 0 (zero) volts through resistor R3. Resistor R2 across capacitor C1 is of such a high value (1 Meg-ohm) compared to R1 (10 K-ohm) that it has a negligible effect on the charge. In this position capacitor C1 is charged to a positive voltage through resistor R1 and that positive voltage is seen at the RESET pin of the ESP-01 Wi-Fi module as a logic 1 (high) signal. Let’s assume the switch S1 is in the Normally Closed (N.C.) position. How the Reset Circuit Works: Refer to the sending unit wiring diagram. The solution involved using RC (Resistor, Capacitor) networks and a SPDT switch with both a Normally Open (N.O.) and Normally Closed (N.C.) set of contacts to create a reset pulse any time the switch changed state. To wake the module up from deep sleep mode required applying a (logic) high-to-low-to-high pulse to the RESET pin of the module. However, a unique challenge was encountered having to do with waking the module up when the door position switch was opened or closed. Putting the ESP-01 module in its low power deep sleep mode is fairly simple and only requires a few lines of code in the software. The intent of this Instructable is to provide a design solution that solves this problem by using passive components that draw very little current when the switch is inactive regardless of its state. transistors) to generate the wake-up signal and that additional circuitry continued to drain significant battery power even though the ESP-01 module was in deep sleep. Since the garage door isn’t opened/closed that often, putting the module to sleep when not in use makes the circuit ideal for being powered by batteries.ĭuring my research in developing a design approach I found that although there are a number of published designs that use the ESP-01 deep sleep mode, they (1) only provided a wake-up signal when the switch was opened or closed but not both, or (2) required additional active circuitry (i.e. I decided to utilize the ESP8266 ESP-01 Wi-Fi module because of its low cost and its ability to go into a low power (battery saver) deep sleep mode when not in use. Since there was no economical way to install new wiring in the house, the sensor had to be wireless and battery operated which in turn meant it had to use very little power. I decided to make this project because there have been a few instances where I forgot I had left the garage door open when turning in for the night. This project is a wireless approach to sensing the open/closed position of my garage door and displaying the door state via an LED indicator in a different location of the house.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |