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Arduino Uno WiFi + TV Remote + LED Sign

Over the weekend, whilst watching TV, I realised that I needed some kind of sign to work out when trains were passing my apartment. There's a railway line right next to me and around four-or-more services pass daily. I'd prefer to be notified in advance and, since I have data sources to tell me when trains are about to come by, I want to make the most of it. Currently that's done by RSS both on my phone and PC, but the whole point is that I'm watching TV and don't want to have to be checking my phone every 2 seconds.

After getting the red LED marquee to work on the old ISA I/O card, I decided it was time to get it plugged into the Arduino. I actually already have an Arduino Uno Wifi next to my TV, which I've recently been using to translate my TV remote control codes (similar to what I did with the old B&O TV) into Yamaha remote control codes for control of volume with one remote. Adding the LED marquee would let me know when a button was successfully pressed ... and it would also tell me when trains were coming past!

I hadn't actually worked with the WiFi on the Arduino yet, so that was a bit of an experience. The RF side of things was working fine and I had already worked out the wiring requirements for the LED display thanks to the old I/O card.

Getting the ESP8266 Online

The Arduino Uno Wifi is an Arduino Uno board with an embedded ESP8299 microcontroller. The basic idea is that the two units talk serial to each other, when configured to do so. If you want to program one, or the other, you have to adjust the serial communications path on the board via a tiny row of switches. Jaycar has a minimal instruction sheet here, but it's enough to get you started. From the information, please set your Arduino Uno Wifi's tiny switch row to: 1:OFF,2:OFF,3:OFF,4:OFF,5:ON,6:ON,7:ON,8:OFF.

I would want this unit to act by itself as both a web server and web requestor, so I needed to find code for both. Before this we need to set up the Arduino IDE for use with the ESP8266. I found a great tutorial here, but otherwise, the steps are pretty simple. Open the Arduino IDE, go to Preferences and then paste this URL into to the additional boards list: http://arduino.esp8266.com/stable/package_esp8266com_index.json.

Once done, go to the board manager and search for ESP8266...

Install the relevant row and then restart the Arduino IDE. From here, you should have a new selection list in the boards drop-down...

...and then, once selected, a hideous amount of new options to adjust the programming!

The main advice is to not touch any of them, apart from the serial port. You'll need to work out which one your Arduino is connected to, but depending on if you even had serial ports in the first place, it should be pretty obvious. I'm working on a Mac Mini and my Arduino was connected via cu.usbserial-1460. From here, open the Serial Monitor and hit reset on the Arduino.

What garbage is that? I then started from the slowest and tested each baud... turns out if you set to 74880 then you'll get the following...

What a weird port number? It seems that just the initial header information is at that BAUD rate. Afterwards, it'll be at whatever you've set in the code you upload.

Running A Web Server

So, where were we? We have a connected device, so let's grab the first example from here and compile it. After installing the ESP8266 libraries, this code should compile with zero issues. If you happen to have any, then write a comment below, providing as much detail as possible. If it's worked, then check the code and adjust the Wifi SSID and password to match your local AP. Hit upload and cross your fingers and toes... hopefully you'll get the following output:

Yes! Now, you need to switch OFF switch 7 on the little switch header on the Arduino. This pin enables the programming mode and we now want it in the run mode. Note also that we've now set the baud to 115200, so change your serial monitor to that too... Do you get the following after hitting the reset key on the Arduino?

Associated! And with a nice IP! So what does the web browser say?

WIN!

HTTPS Web Requests with the ESP8266

The basic ESP8266 examples use WiFiClient, but this only works with HTTP requests. My server runs over HTTPS, so we need to use WifiSecureClient for secure web requests. To call an HTTPS service, you'll need to get the fingerprint from the SSL certificate. Browse to the site in a regular web browser and check out the properties of the lock next to the URL in the address bar. Somewhere in there you'll find the required data.

And from there, edit the WifiClient Example to carry out an SSL request using these instructions:

#include <esp8266wifi .h>

const char* ssid = "********";
const char* password = "********";
const char* host = "api.github.com";
const char* fingerprint = "CF 05 98 89 CA FF 8E D8 5E 5C E0 C2 E4 F7 E6 C3 C7 50 DD 5C";

void setup()
{
  Serial.begin(115200);
  Serial.println();

  Serial.printf("Connecting to %s ", ssid);
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED)
  {
    delay(500);
    Serial.print(".");
  }
  Serial.println(" connected");
}


void loop()
{
  WiFiClientSecure client;
  Serial.print("[connecting to ");
  Serial.println(host);
  if (client.connect(host, 443)) {
    Serial.println("connected]");
    if (client.verify(fingerprint, host)) {
      Serial.println("[certificate matches]");
    } else {
      Serial.println("[certificate doesn't match]");
    }
    Serial.println("[Sending a request]");
    client.print(String("GET /") + " HTTP/1.1\r\n" +
                 "Host: " + host + "\r\n" +
                 "Connection: close\r\n" +
                 "\r\n");
    Serial.println("[Response:]");
    while (client.connected() || client.available())
    {
      if (client.available())
      {
        String line = client.readStringUntil('\n');
        Serial.println(line);
      }
    }
    client.stop();
    Serial.println("\n[Disconnected]");
  }
  else
  {
    Serial.println("connection failed!]");
    client.stop();
  }
  delay(5000);
}

And hopefully, you'll get something similar to the following in your serial terminal.

{ll⸮⸮|⸮d⸮|⸮d⸮b|⸮⸮⸮⸮s⸮b⸮c⸮⸮'o⸮dg'⸮⸮⸮cp⸮⸮dsdrlx⸮o⸮⸮d⸮⸮co⸮|l⸮⸮c⸮⸮go⸮d⸮⸮$`⸮'o$`gs⸮⸮⸮ob⸮$;⸮⸮gc⸮l⸮⸮dl⸮⸮d`⸮⸮'⸮

Connecting ...
scandone
........scandone
.scandone
state: 0 -> 2 (b0)
state: 2 -> 3 (0)
state: 3 -> 5 (10)
add 0
aid 1
cnt 

connected with COMEGETSOME, channel 6
dhcp client start...
ip:192.168.1.121,mask:255.255.255.0,gw:192.168.1.1

Connected to COMEGETSOME
IP address:	192.168.1.121
mDNS responder started

connecting to api.github.com
Using fingerprint '59 74 61 88 13 CA 12 34 15 4D 11 0A C1 7F E6 67 07 69 42 F5'
requesting URL: /repos/esp8266/Arduino/commits/master/status
request sent
headers received
esp8266/Arduino CI has failed
reply was:
==========
{"state":"pending","statuses":[],"sha":"1e17dddd895883806c9bfd3dd7b7042aa813d94f","total_count":0,"repository":{"id":32969220,"node_id":"MDEwOlJlcG9zaXRvcnkzMjk2OTIyMA==","name":"Arduino..."}
==========
closing connection

Nice, we can successfully pull data from a HTTPS source. Let's rig up a polling system to get the data each minute.

Polling for Data + Extra Buttons

So, we're able to pull data from the internet, but I also want this unit to be a mini webserver. If I used Delay() to spread out the web-polling calls, then I'd halt the entire unit. We can't have it wait when it needs to be handling button presses from the web interface. Instead, we'll take a snapshot of the current internal millisecond counter using millis() and then check how many milliseconds have passed to work out if we should try and grab new data.

#include <ESP8266WiFi.h>
#include <WiFiClient.h>
#include <ESP8266WiFiMulti.h> 
#include <ESP8266mDNS.h>
#include <ESP8266WebServer.h>   // Include the WebServer library

ESP8266WiFiMulti wifiMulti;     // Create an instance of the ESP8266WiFiMulti class, called 'wifiMulti'
ESP8266WebServer server(80);    // Create a webserver object that listens for HTTP request on port 80

void handleRoot();              // function prototypes for HTTP handlers
void handleNotFound();
void handleRemote();
unsigned long lastMillis;
const char* host = "trainfinder.otenko.com";
const int httpsPort = 443;
const char fingerprint[] PROGMEM = "BC 9C 56 D5 8E 7A FE CC 0C F7 A2 21 1F C5 7B 9A C0 FA 15 41";
String last_line = "";

void setup(void) {
  Serial.begin(9600);
  delay(100);
  Serial.println("\n!START");
  wifiMulti.addAP("COMEGETSOME", "blahblahblah");
  while (wifiMulti.run() != WL_CONNECTED) { delay(250); }
  Serial.println(WiFi.SSID());
  Serial.println(WiFi.localIP());

  server.on("/", HTTP_GET, handleRoot);
  server.on("/buttons", HTTP_POST, handleRemote);
  server.onNotFound(handleNotFound);
  server.begin();
  
  lastMillis = millis();
}

void loop(void){
  server.handleClient();
  if ((millis() - lastMillis) > (60 * 1000)) {
    WiFiClientSecure client;
    client.setFingerprint(fingerprint);
  
    if (!client.connect(host, httpsPort)) {
      Serial.println("!FAILED");
    } else {
      String url = "/some/cool/url";    
      client.print(String("GET ") + url + " HTTP/1.1\r\nHost: " + host + "\r\nConnection: close\r\n\r\n");
      while (client.connected()) {
        String line = client.readStringUntil('\n');
        if (line == "\r") break;
      }
      bool foundLastLine = false;
      String line = "";
      while(client.available()) {   
        line = client.readStringUntil('\n');
        if (last_line.equals("") || foundLastLine) {
          Serial.println(line);
          last_line = String(line);
          delay(6500); //space out the data to the Arduino
        }
        if (last_line.equals(line)) {
          foundLastLine = true;
        }
      }
      if (!foundLastLine) last_line = line;
    }
    lastMillis = millis();
  }
}

void handleRoot() {
  server.send(200, "text/html", "<form action='/buttons' method='POST'>" \
      "<input type='submit' name='pwr_plz' value='PWR!'/>" \
      "<input type='submit' name='vol_dn' value='VOL-'/>" \
      "<input type='submit' name='vol_up' value='VOL+'/>" \ 
    "</form><br/><br/>Last Line: <pre>" + last_line + "</pre>");   
}

void handleRemote() {
  if (server.hasArg("vol_up")) {
    Serial.println("!VOLUP");
  } else if (server.hasArg("vol_dn")) {
    Serial.println("!VOLDN");
  } else if (server.hasArg("pwr_plz")) {
    Serial.println("!POWER");
  }
  server.sendHeader("Location","/");
  server.send(303);
}

void handleNotFound(){
  server.send(404, "text/plain", "404: Not found");
}

Just for fun, here's the first shot of me writing the code. Instead of 'text/html', I was still outputting 'text/plain' and, well, as expected, got the following...

After fixing that, the screenshot below was taken. Of course, it doesn't match the code above, but you get the idea.

The basic idea is to print out the raw html to the browser. From here there's a form that has the buttons which post back to the ESP8266. The controller then sees the post, sends the command via Serial to the Arduino and then redirects the user back to the main form.

Now to get the Arduino to consume it.

ESP8266 to Arduino

We've currently had the ESP8266 piped directly out the USB Serial port. Now we want it to talk to the Arduino internally. To do this, the tiny onboard switch needs to have all switches off except for 1 and 2. This then routes the RX/TX directly from the ESP8266 to the Arduino. From here though, the unit becomes a black-box. We have no idea what the ESP8266 is saying to the Arduino, and vice-versa, as the connection via the USB serial port has been severed. We can only hope that the data we're sending through is what we want!

If you check the shots above of the data the ESP8266 sends, you can see that we want to skip a bit of the earlier stuff. To do this, I defined a "!START" command which the Arduino should look for before bothering to deal with any of the data from the serial channel. From there, anything starting with a "!" is a command, whereas anything else is to be printed to the LED Display.

Oh yeah, that TV Remote bit

I previously had an amplifier that ran over ARC over HDMI and also received controls... but half the time it'd switch on to Optical and just would not switch back to ARC without a lot of screwing around. No amount of power cycling, cable switching or button pressing would get it back. So it went to the farm. Instead, I purchased a beautiful old Yamaha amp for AUD$5 and then realised I had to get up and control it by hand. Not optimal, so I search google for the remote codes.... they didn't exist, so I search eBay for a spare remote... they didn't exist... but one guy in Spain had a company that programmed third-party remotes and had one for this amp!

It arrived, and I plugged it through the same code I used for the B&O TV. Over the serial, the codes and bits were reported, showing me that it used the "NEC" protocol. I recorded the codes for the buttons I wanted. I then did the same with my Sony TV Remote for buttons that I wanted to re-purpose. The goal was to have the TV Volume buttons also trigger the amp volume. This worked nicely, via an external IR LED that sits in front of the amp.

Of course, the TV volume still shifts, so I made the amp volume shift 4 times per button press... meaning the surround is always louder than the TV. Doesn't hurt to have a little bit of tinny sound from the TV also... a second center channel?

To make everything compile, install Ken Shirrif's IRremote library, available via the Arduino GUI...

The code is in the next segment.

Hooking up the LED Sign

I've used a font found online, but it seems that Arduino has one built-in? 5x7 font. Either way, the 3 data lines and 7 row-enable pins need to find homes in the Arduino digital IO pins. Make sure you don't use digital pin 0 or 1 as that's the serial channel to the ESP8266. I found this out later below...

Once hooked up, just use a similar loop process as per any LED display: Disable all rows, send out the columns to be lit for the first row, enable that row and quickly disable it. Then do the same for the next 6 rows. As quickly as possible! More information on lighting this sign is over here.

#include <IRremote.h>
#include "myfont.h"
#include "digitalWriteFast.h"

int RECV_PIN = 13;
IRrecv irrecv(RECV_PIN);
decode_results results;
IRsend irsend;

void setup()
{
  Serial.begin(9600);
  irrecv.enableIRIn(); // Start the receiver

  pinModeFast(0, OUTPUT);
  digitalWriteFast(0, LOW);
  pinModeFast(2, OUTPUT);
  digitalWriteFast(2, LOW);
  pinModeFast(12, OUTPUT);
  digitalWriteFast(12, LOW);

//matrix led row drivers
  for (int p = 0; p <= 11; p++) {
    pinModeFast(p, OUTPUT);
    digitalWriteFast(p, LOW);
  }
}

unsigned long last_time = millis();
unsigned long scroll_time = millis();
unsigned long scroll_pause = millis();
bool is_off = true;
int loop_count = 0;
String serialString = " Warming up..";
bool found_start = false;
int charOffset = 0;
int ccol;

void loop() {
  if (irrecv.decode(&results)) {    
    loop_count = 0;
    switch (results.value) {
      case 4841:
      case 0xA90:
        irsend.sendNEC(0xDE21807F, 32);
        if (is_off) {
          serialString = " Power ON!";
          is_off = false;
        } else {
          serialString = " GOOD BYE!";
          is_off = true;
        }
        break;
      case 0x490:
        irsend.sendNEC(0xDE21B04F, 32);
        delay(50);
        irsend.sendNEC(0xDE21B04F, 32);
        delay(50);
        irsend.sendNEC(0xDE21B04F, 32);
        serialString = " VOLUME UP!";
        break;
      case 0xC90:
        irsend.sendNEC(0xDE21708F, 32);
        delay(50);
        irsend.sendNEC(0xDE21708F, 32);
        delay(50);
        irsend.sendNEC(0xDE21708F, 32);
        serialString = " VOLUME DOWN!";
        break;
      case 0xFFFFFFFF:
        irsend.sendNEC(0xFFFFFFFF, 32);
        break;
        //sony teletext red
      case 21225:
        irsend.sendNEC(3726721215, 32);
        serialString = " INPUT!";
        //sony teletext green
      case 13033:
        irsend.sendNEC(3726717135, 32);
        serialString = " MODE UP!";
        break;
        //sony teletext yellow
      case 29417:
        irsend.sendNEC(3726735495, 32);
        serialString = " MODE DOWN!";
        break;
      default:
        Serial.println(results.value);
        Serial.println(results.bits);
        break;
    }
    delay(250);
    irrecv.enableIRIn();
    irrecv.resume(); // Receive the next value
  }

  if (charOffset == 0 && Serial.available() && ((millis() - last_time) > 4000)) {
    last_time = millis();
    serialString = Serial.readStringUntil('\n') + '\0';
    loop_count = 0;
    scroll_pause = millis();
  }
  
  //draw LEDs
  for (int row = 0; row < 7; row++) 
  {
    for (int col = 0; col < 90; col++) {
      if (((col / 5) + charOffset) < 60) {
        ccol = (charOffset * 5) + col;
        digitalWriteFast(2, ((font[serialString[ccol / 5]][ccol % 5] & (1 << (6 - row))) > 0) ? HIGH : LOW);
      } else {
        digitalWriteFast(2, LOW);
      }
      digitalWriteFast(12, HIGH);
      delayMicroseconds(5);
      digitalWriteFast(12, LOW);
    }
    digitalWriteFast(row + 5, HIGH);
    delayMicroseconds(75);
    digitalWriteFast(row + 5, LOW);
  }
  
  if ((millis() - scroll_pause > 2500)) {
    if ((serialString.length() > 18)) {
      if (millis() - scroll_time > 180) {
        charOffset++;
        if (charOffset > serialString.length()) {
          charOffset = 0;
          loop_count++;
          scroll_pause = millis();
          if (loop_count > 10) serialString = "";
        }
        scroll_time = millis();
      }
    } else {
      loop_count++;
      if (loop_count > 100) serialString = "";
      charOffset = 0;
    }
  }
}

Overloading Arduino Pins

Anyone watching above, or in the previous post where I hooked the display up to the old PC, was probably screaming in their seats. It's well known that you should NOT draw too much current through the pins on any microprocessor. As soon as I started hooking up more modules onto this unit, things started going haywire and it quickly dawned on me. My seven line-enable pins were being brought LOW to enable the rows... but these were actually working as the single GND conduit for the entire bloody LED display!

I quickly referred to the previous module that ran this sign and saw there was a 74LS145 binary counter in between the Atmel Microcontroller and the 7 enable rows. A quick review of the datasheet shows that this chip can 'sink' up to 15v and is 'great for driving LEDs'. Right... they were properly routing the GND wires away from the microcontroller and using the 145 as a set of transistors. They even saved 3 data lines in the process! I only had a ULN2003 (which would still use 7 lines) and there were no 74LS145 to be found at Jaycar!

This now directed the current away from the microcontroller... but didn't enhance the brightness.

Speeding up the Refresh Rate

It occurred to me that my refresh rates weren't anywhere near as good as the original controller that the sign contained. My loop is busy checking clocks, serial ports and mucking around, so it was never going to actually go fast enough. The code above could run a single segment OK, but started to scale worse as the bit shifting got longer. One trick, which is actually already implemented in the source above is to use an external library to make the digital pin manipulation faster.

With this implemented, there was less flickering and I found that three segments (90 LEDs per row) looked good. One final note is that you shouldn't really use pins 0 or 1 if you've got the serial enabled. They actually present the TX/RX lines and the serial data and the serial data to the Arduino is visible on them. In this case, it was the serial data to/from the ESP8266. In the case below, I had the three data lines required to drive the display on digital pins 0,1,2...

Shifting those to spare pins higher...

Yessssss! It works really nicely.