Front Door RF keypad lock

Forums › Gadgets, robotics, home automation, electronics (including wearables) › Front Door RF keypad lock

chimera

506 posts

Ultimate Geek

#198940 28-Jul-2016 23:47

I bought an RF keypad based front door lock from the states on an Amazon sale cheap, about $120 NZ landed. I thought the Mi brand would be fairly cheap quality based on the price, but it isn't actually too bad at all. Solidly built. The only possible issue is the 4 x AA batteries in the back to trigger the lock/unlock mechanism didn't last long - I say possible, as I can't remember if they were new batteries I put in or ones my kids use in their Wii remotes! I guess I'll find out soon now I have brand new batteries in, anyways I digress...

I wanted to have the door lock automated / controlled from OpenHAB, so ripped open the key fob and wired it up. I got it working with an ESP8266-01 initially, but had issues because you have to keep GPIO pins 0 high on startup - doing this triggered the transistor to switch, unlocking the front door on power up. Not good! Experimented with NPN and PNP combo's but eventually gave up - I went to a Wemos with a couple 2N7000 MOSFETs and 2 x 10K pull down resistors. The keyfob generally uses 6V's (2 x 3V button cell batteries) but I'm just powering it using 5V from the breadboard - seems to be ok, no different than when a battery gets old I guess.

The Wemos is pretty cool, but its a bit bigger than the native ESP8266. I have an ESP8266 v12 around somewhere so might give that a go instead as its smaller. Anyhow the point of the post is an option to provide a basic / cheap alternative automated front door lock. I have it triggered to lock automatically at night, and can remotely unlock/lock the front door from my iPhone too. Always good for those "did you lock the front door honey?",... "no, i told you too",... "but I was already in the car you were last out",... "well I'm not walking back up the front steps to check the door, if you weren't so %#$ lazy i wouldn't have had to run around after the kids getting them ready to go out while you sit there all afternoon drinking beer and watching the league!",... "argh, i'll lock the door with my phone. and oh yeah, you're right - i've been drinking,... here you drive" moments.

datahawk

251 posts

Ultimate Geek

Lifetime subscriber

#1600942 29-Jul-2016 17:32

Nice job.

I also build a lot of ESP8266 Wifi Controlled devices or sensor logging modules from scratch (usually a mixture of ESP-01 and NodeMcu ESP-12 boards).

Yep, the brief activation of the GPIO's during boot up can be an annoying issue along with some devices not booting at all because GPIO0 is LOW during power up and it has gone into firmware flash mode.

To solve this problem on some of my device designs I add a small 7555 or 555 timer delay circuit that isolates the GPIO ground connection for a few seconds while the board powers up....

GPIO Delay Circuit

The above is my 3.3V version using a ICM7555 timer.

The load can't activate for two seconds while the ESP-01 boots up even if the GPIO goes high during this period.

chimera

506 posts

Ultimate Geek

#1600961 29-Jul-2016 18:03

datahawk:

Nice job.

I also build a lot of ESP8266 Wifi Controlled devices or sensor logging modules from scratch (usually a mixture of ESP-01 and NodeMcu ESP-12 boards).

Yep, the brief activation of the GPIO's during boot up can be an annoying issue along with some devices not booting at all because GPIO0 is LOW during power up and it has gone into firmware flash mode.

To solve this problem on some of my device designs I add a small 7555 or 555 timer delay circuit that isolates the GPIO ground connection for a few seconds while the board powers up....

The load can't activate for two seconds while the ESP-01 boots up even if the GPIO goes high during this period.

Nice, great idea thanks! I like the idea of building as small as possible, the Wemos is really good but a little bigger than the ESP-01. On a board I did earlier (the one in the background of the image I posted above) which opens or closes my blinds (with an ESP-01) I cheated by putting a 420uF capacitor at the base of the transistor (base switched by the ESP GPIO pin) which worked perfectly on sucking up the power on boot up. Only thing I didn't like was the numerous resistors and transistors to get it to work, especially if you consider all its doing is effectively flicking a switch. Good learning curve though. I might just shift the automated blinds code to the Wemos instead, so have it control front door and blinds on the one board.

I'm a noob when it comes to electronics, only really started playing with this stuff several months ago. Now you've replied, I have you on my hit list for questions...

chimera

506 posts

Ultimate Geek

#1602536 1-Aug-2016 21:04

Sharing's caring, so figured I may as well throw this on instructables.com in case others want better instructions, link here if needed:

http://www.instructables.com/id/RF-Door-Lock-ESP8266-and-OpenHAB/