There has been a bit of chatter on the channel recently about me NOT providing links and details regarding the items that make up the mailbag videos.
Here are my reasons:
1. The mail you see me open is 3-6 months old! That's right, I'm still hugely in catch up mode after the insanity buying sprees of 2022. This means the information would most likely be out of date.
2. I shop pretty much 100% on AliExpress. The shops come and go, and often I look back for an item only to find it does not exist on the shop anymore, or even that the whole shop is missing!
3. The items I order are dodgy as anything. I have a limited income stream and so I deliberately choose the cheapest items I can - often they are fake, used or simply not fit for purpose. I love this about shopping online at AliExpress - it's got a real "life is like a box of chocolates" feel about it, but I would not feel comfortable pointing people to these items.
Finally, I nearly always do a screenshot on the video for each item so that you can use these search terms on your favourite site to track down a similar item. If I fail to do that, please let me know in the comments section.
Having said all of that - onwards to the silliness that is Mailbag #29.
I love the idea of a small micro-controller "punching" above it's weight. An anaemic tiny processor bossing around motors when it has no right to is my idea of heaven. OK, so I don't get out much.
AND...if you add a little iOT into the recipe, then I'm there for the "fun".
So it happens that we are looking at a gate opening/closing mechanism for the bottom of the driveway.
You can buy them commercially and that's fine for regular sane people - but what about using a tiny ESP-01S to act as an Access Point, run a web server and turn on and off stuff WAY beyond it's capacity given it's flash memory and GPIO limitations?
Sounds like a little experimentation might be required to tip the balance from BUY to DIY.
Yes please!
This project has some distinct phases:
run the 3.3V ESP-01s and a heavy inductive motor (24V) from the same power supply
extend the ESP-01s meagre output capacity to be able to address many GPIOs using a 74HC595N shift register
use a ULN2803 with it's inbuilt flyback diode to handle the motor and it's current requirement
make an Access Point to activate the gate from any WiFi capable device
Let's go!
The power issue was solved (as I've done before) with a combination of a buck/boost module (LM2596 based) and LM1117 3.3V linear voltage regulator. The final drop was 20.5V to 7.5V using the switching regulator and then 7.5V to 3.3V using a TO-220 format LM1117 regulator.
I kept calling this an LM117 regulator in the video - apologies!
With this rig the "top" rail is 20.5V (for the motor) and the "bottom" rail is a steady 3.3V. One hilarious event during testing was the destruction of a 16V rated capacitor I forgot to remove which was still sitting in the top rail when I upped the voltage - love that smell of magic smoke!
The 74HC595N shift register part of the project was fairly easily achieved given that I have worked with these units earlier on this blog.
I will post the code below so that you can see just how simple this stuff can be using standard, mostly "borrowed", code.
Next up was the ULN2803 component - this is a very handy darlington transistor array that comes complete with a flyback diode (marked in the diagram below with a red arrow and circle) to hopefully prevent damage to the controller of an inductive load - e.g. let's not fry the little ESP8266 with a big nasty kick back from the motor when it stops!
Finally, I coded up the ESP-01S so that it behaved as a WiFi Access Point and could, er, "open the gate" complete with warning lights and buzzers. Very exciting!
/* Using an ESP-01s to turn on a motor, as well as running a few lights and buzzers all via a 74HC595N and ULN28703 OneCircuit Sun 12 Feb 2023 19:52:25 AEDT*/#include <ESP8266WiFi.h>#include <ESP8266WebServer.h>/* Put your SSID & Password */constchar* ssid = "GateControl"; // Enter SSID hereconstchar* password = "1234"; //Enter Password here//Pin connected to latch pin (ST_CP) of 74HC595constint latchPin = 0;
//Pin connected to clock pin (SH_CP) of 74HC595constint clockPin = 1;
////Pin connected to Data in (DS) of 74HC595constint dataPin = 2;
byte shiftbyte = 0; // the state of the shift registerlong motor = 0;
boolean motorun = false;
bool GATEstatus = false;
bool openclick = false;
long currenttime = 0;
int turnoffmotortime = 5000;
/* Put IP Address details */
IPAddress local_ip(192, 168, 2, 1);
IPAddress gateway(192, 168, 2, 1);
IPAddress subnet(255, 255, 255, 0);
ESP8266WebServer server(80);
void setup() {
pinMode(latchPin, OUTPUT);
pinMode(dataPin, OUTPUT);
pinMode(clockPin, OUTPUT);
delay(20);
// clear register
shiftbyte = 0b00000000;
updateShiftRegister();
delay(500);
WiFi.softAP(ssid, password);
WiFi.softAPConfig(local_ip, gateway, subnet);
delay(100);
server.on("/", handle_OnConnect);
server.on("/gateon", handle_gateon);
server.on("/gateoff", handle_gateoff);
server.onNotFound(handle_NotFound);
server.begin();
}
void turnonsequence() {
// turn off green
shiftbyte = 0b00000000;
updateShiftRegister();
// turn on red and buzzer
shiftbyte = 0b00100100;
updateShiftRegister();
delay(3000);
shiftbyte = 0b00000000;
updateShiftRegister();
// flashing yellow, buzzer and motor
motorun = true;
motor = millis(); // start timingwhile (motorun) {
shiftbyte = 0b01001000;
updateShiftRegister();
delay(200);
shiftbyte = 0b01110000;
updateShiftRegister();
delay(200);
shiftbyte = 0b01000000;
updateShiftRegister();
currenttime = millis();
if (currenttime - motor > turnoffmotortime) {
motorun = false;
}
}
shiftbyte = 0b00000000;
updateShiftRegister();
GATEstatus = !GATEstatus;
}
void updateShiftRegister()
{
digitalWrite(latchPin, LOW);
shiftOut(dataPin, clockPin, MSBFIRST, shiftbyte);
digitalWrite(latchPin, HIGH);
}
void loop() {
server.handleClient();
// green to start with
shiftbyte = 0b00000010;
updateShiftRegister();
if (!GATEstatus && openclick) {
turnonsequence();
}
if (GATEstatus && !openclick) {
turnonsequence();
}
}
void handle_OnConnect() {
GATEstatus = false;
openclick = false;
server.send(200, "text/html", SendHTML(false));
}
void handle_gateon() {
openclick = true;
server.send(200, "text/html", SendHTML(true));
}
void handle_gateoff() {
openclick = false;
server.send(200, "text/html", SendHTML(false));
}
void handle_NotFound() {
server.send(404, "text/plain", "Not found");
}
String SendHTML(uint8_t gate) {
String ptr = "<!DOCTYPE html>\n";
ptr += "<html>\n";
ptr += "<head>\n";
ptr += "<title>Gate Control</title>\n";
ptr += "</head>\n";
ptr += "<body>\n";
ptr += "<h1>Gate Control</h1>\n";
ptr += "<p>Press to open and close gate.</p>\n";
ptr += "<form method=\"get\">\n";
if (gate)
ptr += "<input type=\"button\" value=\"Gate open\" onclick=\"window.location.href='/gateoff'\">\n";
else
ptr += "<input type=\"button\" value=\"Gate closed\" onclick=\"window.location.href='/gateon'\">\n";
ptr += "</form>\n";
ptr += "</body>\n";
ptr += "</html>\n";
return ptr;
}
I really enjoyed this project and indeed I think that as part of my continuing learning experience I may repeat the whole project using I2C (two wires!) instead of a shift register in another blog post and video. Watch this space!
I was at an antique store recently, just browsing, not looking for anything in particular when I spied a lovely crystal vase - a steal at AUD$15.
Straight away I thought of the reflective and refractive possibilities should I shoehorn in a small solar panel and the stable joule thief (padauk version) together with the new "3D" LED PCB.
After soldering it all up and blasting the code onto the PFS154, I glued the lot into the vase and I'm happy to report that the light provided at night is quite lovely!
A lovely bunch of items from China - the weird one was a sound activated USB LED module which for some reason I thought was broken when the video clearly shows it was dancing to my voice! It must have been late at night when I filmed that one.
Anyway, despite that gaffe, please enjoy - it's a LOT of LED action!
