add status topic and publish after sending text to sign

RESTful version of simple socket listener.

LICENSE.txt

@@ -0,0 +1,7 @@
+Copyright 2024 Fabian Müller <fabian@fablab-altmuehlfranken.de>
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

platformio.ini

@@ -13,10 +13,11 @@ platform = espressif8266
 framework = arduino
 monitor_speed = 115200
 upload_speed = 500000
+upload_protocol = espota
+upload_port = led-marquee-sign
 
 # Serial1 (sign data) maps to D4 by default
 [env:d1_mini]
 board = d1_mini
-
-[env:nodemcuv2]
-board = nodemcuv2
+lib_deps = adafruit/Adafruit MQTT Library@^2.5.8
+lib_ignore = WiFi101

src/credentials.h.example

@@ -5,4 +5,9 @@ namespace credentials {
     const String psk = "my PSK";
 
     const String mdnsHostname = "led-marquee-sign";
+
+    const String mqtt_hostname = "mqtt-broker";
+    const uint16_t mqtt_port = 1883;
+    const String mqtt_username = "user";
+    const String mqtt_password = "pass";
 }

src/main.cpp

@@ -1,12 +1,31 @@
+#include <ESP8266WiFi.h>
 #include <ESP8266WiFiMulti.h>
 #include <ESP8266mDNS.h>
 #include <ESP8266WebServer.h>
+#include <WiFiUdp.h>
+#include <ArduinoOTA.h>
+#include "Adafruit_MQTT.h"
+#include "Adafruit_MQTT_Client.h"
 
 #include "credentials.h"
 #include "webserver.h"
+#include "socketserver.h"
 #include "util.h"
 
 static ESP8266WiFiMulti wifiMulti;
+static SocketServer socketServer;
+
+#define AIO_SERVER      credentials::mqtt_hostname.c_str()
+#define AIO_SERVERPORT  credentials::mqtt_port
+#define AIO_USERNAME    credentials::mqtt_username.c_str()
+#define AIO_KEY         credentials::mqtt_password.c_str()
+
+WiFiClient client;
+Adafruit_MQTT_Client mqtt(&client, AIO_SERVER, AIO_SERVERPORT, AIO_USERNAME, AIO_KEY);
+Adafruit_MQTT_Subscribe mqtt_subscribe_topic = Adafruit_MQTT_Subscribe(&mqtt, "homeassistant/marquee_sign/text/set");
+Adafruit_MQTT_Publish mqtt_publish_topic = Adafruit_MQTT_Publish(&mqtt, "homeassistant/marquee_sign/text/status");
+
+void MQTT_connect();
 
 void setup() {
     // serial console, for use via USB (also exposed to TXD0/RXD0 GPIOs)
@@ -18,7 +37,10 @@ void setup() {
     Serial1.begin(9600);
 
     // configure WiFi and connect to the network
+    WiFi.mode(WIFI_STA);
+    WiFi.hostname(credentials::mdnsHostname);
     wifiMulti.addAP(credentials::ssid.c_str(), credentials::psk.c_str());
+
     Serial.println("Connecting to Wi-Fi network...");
     while (wifiMulti.run() != WL_CONNECTED) {
         delay(1000);
@@ -30,23 +52,61 @@ void setup() {
     Serial.print(", IP address: ");
     Serial.println(WiFi.localIP());
 
+    ArduinoOTA.begin();
+
+    mqtt.subscribe(&mqtt_subscribe_topic);
+
     // might be handy to have the IP written on the sign
     sendTextToSign(WiFi.localIP().toString());
 
-    // publish this service using mDNS so that it's easy to find it in the LAN
-    if (MDNS.begin(credentials::mdnsHostname)) {
-        Serial.println("mDNS started up successfully");
-    } else {
-        Serial.println("Error: failed to start mDNS");
-    }
-
     // configure HTTP endpoints
     configureWebServer();
 
-    // don't forget to start the webserver!
+    // don't forget to start all the services
     webServer.begin();
+    socketServer.begin();
 }
 
 void loop() {
     webServer.handleClient();
+    socketServer.handleClient();
+
+    ArduinoOTA.handle();
+
+    MQTT_connect();
+
+    Adafruit_MQTT_Subscribe *subscription;
+    while ((subscription = mqtt.readSubscription(5000))) {
+        const char* signText = (char *)mqtt_subscribe_topic.lastread;
+
+        sendTextToSign(signText);
+
+        mqtt_publish_topic.publish(signText);
+    }
+}
+
+void MQTT_connect() {
+    int8_t ret;
+
+    // Stop if already connected.
+    if (mqtt.connected()) {
+        return;
+    }
+
+    uint8_t retries = 6;
+    // connect will return 0 for connected
+    while ((ret = mqtt.connect()) != 0) {
+        mqtt.disconnect();
+
+        // wait 10s till next try
+        for (int i = 0; i < 10000; i += 5) {
+            ArduinoOTA.handle();
+            delay(5);
+        }
+
+        retries--;
+        if (retries == 0) {
+            ESP.restart();
+        }
+    }
 }

src/socketserver.h

@@ -0,0 +1,34 @@
+#pragma once
+
+class SocketServer {
+public:
+    static constexpr int Port = 3000;
+
+    void begin() {
+        _server.begin();
+    }
+
+    void handleClient() {
+        auto client = _server.available();
+
+        if (client) {
+            Serial.println("Client connected to socket server: " + client.remoteIP().toString() + ":" + client.remotePort());
+        } else {
+            return;
+        }
+
+        while (client.connected()) {
+            while (client.available() > 0) {
+                auto chr = client.read();
+                Serial.write(chr);
+                Serial1.write(chr);
+            }
+        }
+        client.stop();
+        Serial.println();
+        Serial.println("Client disconnected");
+    }
+
+private:
+    WiFiServer _server{Port};
+};

src/util.h

@@ -1,18 +1,397 @@
 #pragma once
 
-enum Brightness {
-    Normal,
-    Bright,
+#include <map>
+#include <set>
+#include <unordered_map>
+
+// TODO: reverse engineer builtin and custom bitmaps
+
+// seems like our sign listens to messages on this address
+// it is also the software's default value
+static constexpr auto SIGN_ADDRESS = 128;
+
+enum class FontType {
+    Font5x6Short = 'q',
+    Font5x11ShortAndWide = 'r',
+    Font7x6Default = 's',
+    Font7x11Wide = 't',
+    Font7x9 = 'u',
+    Font7x17ExtraWide = 'v',
+    FontSmallFont = 'w',
 };
 
-void sendTextToSign(String text, Brightness brightness = Bright) {
-    // debugging
-    Serial.print("Sending text \"");
-    Serial.print(text);
-    Serial.println("\"");
+enum class Brightness {
+    Normal = 'a',
+    Bright = 'b',
+};
 
-    // TODO: find out how the brightness attribute in the LED sign is encoded in the UART signal
-    Serial1.print("f01A\\s");
-    Serial1.print(text);
-    Serial1.print("\r\r\r");
+enum class Method {
+    Cyclic = 'A',
+    Immediate = 'B',
+    OpenFromRight = 'C',
+    OpenFromLeft = 'D',
+    OpenFromCenter = 'E',
+    OpenToCenter = 'F',
+    CoverFromCenter = 'G',
+    CoverFromRight = 'H',
+    CoverFromLeft = 'I',
+    CoverToCenter = 'J',
+    ScrollUp = 'K',
+    ScrollDown = 'L',
+    InterlaceToCenter = 'M',
+    InterlaceCover = 'N',
+    CoverUp = 'O',
+    CoverDown = 'P',
+    ScanLine = 'Q',
+    Explode = 'R',
+    PacMan = 'S',
+    FallAndStack = 'T',
+    Shoot = 'U',
+    Flash = 'V',
+    Random = 'W',
+    SlideIn = 'X',
+};
+
+// macros are literal characters prefixed by ^
+enum class Macros {
+    CurrentTime12hWithoutAmPm = 'D',
+    CurrentTime12hWithAmPm = 'E',
+    CurrentTime24h = 'F',
+    CurrentDateMmDdYyyy = 'A',
+    CurrentDateYyyy_Mm_Dd = 'B',
+    CurrentDateMm_Dd_Yyyy = 'C',
+    CurrentDateDd_Mm_Yyyy = 'a',
+    Beep1 = 'q',
+    Beep2 = 'r',
+    Beep3 = 's',
+    Temperature = 'H',
+};
+
+// symbols should be inserted as string representations of their numeric value prefixed by ^
+enum class Symbols {
+    Sun = 66,
+    CloudOrWind = 67,
+    UmbrellaRaining = 68,
+    WallClock = 69,
+    Telephone = 70,
+    Glasses = 71,
+    Faucet = 72,
+    RocketOrSyringeOrSo = 73,
+    WhatTheHell = 74,
+    Key = 75,
+    Shirt = 76,
+    Helicopter = 77,
+    Car = 78,
+    Tank = 79,
+    House = 80,
+    Teapot = 81,
+    Trees = 82,
+    Duck = 83,
+    Scooter = 84,
+    Bicycle = 85,
+    Crown = 86,
+    AppleOrSo = 87,
+    ArrowRight = 88,
+    ArrowLeft = 89,
+    ArrowDownLeft = 90,
+    ArrowUpLeft = 91,
+    Cup = 92,
+    Chair = 93,
+    HighHeel = 94,
+    PrizeCup = 95,
+};
+
+// cartoons are represented as these characters prefixed by ^
+enum class Cartoon {
+    MerryXMas = 'i',
+    HappyNewYear = 'j',
+    FourthOfJuly = 'k',
+    HappyEaster = 'l',
+    HappyHalloween = 'm',
+    DontDrinkAndDrive = 'n',
+    NoSmoking = 'o',
+    Welcome = 'p',
+};
+
+// the descriptions originate from the UTF-16 specification, https://www.ssec.wisc.edu/~tomw/java/unicode.html
+// the extended charset starts where ASCII ends
+enum class ExtendedChar {
+    // Ç
+    LatinCapitalLetterCWithCedilla = 0x80,
+    // ü
+    LatinSmallLetterUWithDiaeresis = 0x81,
+    // é
+    LatinSmallLetterEWithAcute = 0x82,
+    // â
+    LatinSmallLetterAWithCircumflex = 0x83,
+    // ä
+    LatinSmallLetterAWithDiaeresis = 0x84,
+    // à
+    LatinSmallLetterAWithGrave = 0x85,
+    // å
+    LatinSmallLetterAWithRingAbove = 0x86,
+    // ç
+    LatinSmallLetterCWithCedilla = 0x87,
+    // ê
+    LatinSmallLetterEWithCircumflex = 0x88,
+    // ë
+    LatinSmallLetterEWithDiaeresis = 0x89,
+    // è
+    LatinSmallLetterEWithGrave = 0x8a,
+    // Ï
+    LatinCapitalLetterIWithDiaeresis = 0x8b,
+    // Î
+    LatinCapitalLetterIWithCircumflex = 0x8c,
+    // Ì
+    LatinCapitalLetterIWithGrave = 0x8d,
+    // Ä
+    LatinCapitalLetterAWithDiaeresis = 0x8f,
+    // Å
+    LatinCapitalLetterAWithRingAbove = 0x8f,
+    // É
+    LatinCapitalLetterEWithAcute = 0x90,
+    // æ
+    LatinSmallLetterAe = 0x91,
+    // Æ
+    LatinCapitalLetterAe = 0x92,
+    // ô
+    LatinSmallLetterOWithCircumflex = 0x93,
+    // ö
+    LatinSmallLetterOWithDiaeresis = 0x94,
+    // ò
+    LatinSmallLetterOWithGrave = 0x95,
+    // û
+    LatinSmallLetterUWithCircumflex = 0x96,
+    // ù
+    LatinSmallLetterUWithGrave = 0x97,
+    // ÿ
+    LatinSmallLetterYWithDiaeresis = 0x98,
+    // Ö
+    LatinCapitalLLetterOWithDiaeresis = 0x99,
+    // Ü
+    LatinCapitalLetterUWithDiaeresis = 0x9a,
+    // ¢
+    CentSign = 0x9b,
+    // £
+    PoundSign = 0x9c,
+    // ¥
+    YenSign = 0x9d,
+    // urm...
+    UnknownPCurrencySign = 0x9e,
+    // ƒ
+    LatinSmallLetterFWithHook = 0x9f,
+    // á
+    LatinSmallLetterAWithAcute = 0xa0,
+    // Í
+    LatinCapitalLetterIWithAcute = 0xa1,
+    // Ó
+    LatinCapitalLetterOWithAcute = 0xa2,
+    // ú
+    LatinSmallLetterUWithAcute = 0xa3,
+    // ñ
+    LatinSmallLetterNWithTilde = 0xa4,
+    // Ñ
+    LatinCapitalLetterNWithTilde = 0xa5,
+    // a̱
+    LatinSmallLetterAWithMacronBelow = 0xa6,
+    // couldn't find that one in the UTF-16 table
+    LatinSmallLetterOWithMacronBelow = 0xa7,
+    // ¿
+    InvertedQuestionMark = 0xa8,
+    // you can probably imagine what it'll look like
+    LatinCapitalLetterZWithRingAbove = 0xa9,
+    // Ź
+    LatinCapitalLetterZWithAcute = 0xaa,
+    // ń
+    LatinSmallLetterNWithAcute = 0xab,
+    // some weird L with a diagonal line
+    AnotherWeirdSign = 0xac,
+    // Ś or ś, can't tell for sure, let's assume capital
+    LatinCapitalLetterSWithAcute = 0xab,
+    // Ć
+    LatinCapitalLetterCWithAcute = 0xac,
+    // ȩ
+    LatinSmallLetterEWithCedilla = 0xad,
+    // well, you can imagine what it'll look like
+    LatinSmallLetterAWithCedilla = 0xb0,
+    // €
+    EuroSign = 0xb1,
+    // E with some vertical line below
+    LatinCapitalLetterEWithSomeLineBelow = 0xb3,
+    // a with some vertical line below
+    LatinSmallLetterAWithSomeWeirdLineBelow = 0xb4,
+    // α
+    GreekSmallLetterAlpha = 0xe0,
+    // β
+    GreekSmallLetterBeta = 0xe1,
+    // Γ
+    GreekCapitalLetterGamma = 0xe2,
+    // π
+    GreekSmallLetterPi = 0xe3,
+    // Σ
+    GreekCapitalLetterSigma = 0xe4,
+    // σ
+    GreekSmallLetterSigma = 0xe5,
+    // μ
+    GreekSmallLetterMu = 0xe6,
+    // τ
+    GreekSmallLetterTau = 0xe7,
+    // Φ
+    GreekCapitalLetterPhi = 0xe8,
+    // θ
+    GreekSmallLetterTheta = 0xe9,
+    // Ω
+    GreekCapitalLetterOmega = 0xea,
+    // δ
+    GreekSmallLetterDelta = 0xeb,
+    // ∞
+    Infinity = 0xec,
+    // φ
+    GreekSmallLetterPhi = 0xed,
+};
+
+std::unordered_map<uint16_t, uint8_t> createUnicodeToCP437Map() {
+    std::unordered_map<uint16_t, uint8_t> cp437_map;
+
+    cp437_map[0x00E4] = 0x84;  // ä in UTF-16
+    cp437_map[0xC3A4] = 0x84;  // ä in UTF-8
+    cp437_map[0x00F6] = 0x94;  // ö in UTF-16
+    cp437_map[0xC3B6] = 0x94;  // ö in UTF-8
+    cp437_map[0x00FC] = 0x81;  // ü in UTF-16
+    cp437_map[0xC3BC] = 0x81;  // ü in UTF-8
+    cp437_map[0x00C4] = 0x8E;  // Ä in UTF-16
+    cp437_map[0xC384] = 0x8E;  // Ä in UTF-8
+    cp437_map[0x00D6] = 0x99;  // Ö in UTF-16
+    cp437_map[0xC396] = 0x99;  // Ö in UTF-8
+    cp437_map[0x00DC] = 0x9A;  // Ü in UTF-16
+    cp437_map[0xC39C] = 0x9A;  // Ü in UTF-8
+    cp437_map[0x00DF] = 0xE1;  // ß in UTF-16
+    cp437_map[0xC39F] = 0xE1;  // ß in UTF-8
+    cp437_map[0x20AC] = 0xB1;  // € in UTF-16
+    cp437_map[0xE282AC] = 0xB1;  // € in UTF-8 (3 Bytes)
+    cp437_map[0x00B5] = 0xE6;  // µ in UTF-16
+    cp437_map[0xC2B5] = 0xE6;  // µ in UTF-8
+
+    return cp437_map;
+}
+
+String convertToCP437(const String& input) {
+    std::unordered_map<uint16_t, uint8_t> cp437_map = createUnicodeToCP437Map();
+    String output = "";
+    size_t len = input.length();
+
+    for (size_t i = 0; i < len; i++) {
+        char ch = input[i];
+
+        // UTF-8 detection: check for 3 byte UTF-8
+        if ((ch & 0xF0) == 0xE0) {
+            if (i + 2 < len) {
+                uint32_t utf8_char = ((uint8_t)input[i] << 16) | ((uint8_t)input[i + 1] << 8) | (uint8_t)input[i + 2];
+                // skip 2 additional bytes
+                i += 2;
+                if (cp437_map.find(utf8_char) != cp437_map.end()) {
+                    output += static_cast<char>(cp437_map[utf8_char]);
+                    continue;
+                }
+            }
+        }
+        // UTF-8 detection: check for 2 byte UTF-8
+        else if ((ch & 0xE0) == 0xC0) {
+            if (i + 1 < len) {
+                uint16_t utf8_char = ((uint8_t)input[i] << 8) | (uint8_t)input[i + 1];
+                // skip second byte
+                i++;
+                if (cp437_map.find(utf8_char) != cp437_map.end()) {
+                    output += static_cast<char>(cp437_map[utf8_char]);
+                    continue;
+                }
+            }
+        }
+        // single UTF-16 character (or plain ANSI character)
+        else if ((uint8_t)ch < 0x80) {
+            // keep ASCII as is
+            output += ch;
+        }
+        else {
+            uint16_t utf16_char = (uint8_t)ch;
+            // check if character is in UTF-16 range, fallback to ?
+            if (cp437_map.find(utf16_char) != cp437_map.end()) {
+                output += static_cast<char>(cp437_map[utf16_char]);
+            } else {
+                output += '?';
+            }
+        }
+    }
+
+    return output;
+}
+
+String hexDump(String in) {
+    String out;
+    for (size_t i = 0; i < in.length(); ++i) {
+        auto hexChar = String(in[i], HEX);
+        if (hexChar.length() == 1) {
+            out.concat('0');
+        }
+        out.concat(hexChar);
+        out.concat(' ');
+    }
+    return out;
+}
+
+/*
+ * Message syntax:
+ * separator: ~
+ * address (int string): 128
+ * separator: ~
+ * random string(?): f01
+ * method (single char)
+ * format string (see below)
+ * end of message: \r\r\r
+ *
+ * the format string contains the message along with control characters that define some of the formatting
+ * note: we have not tested the UTF-8 capabilities, so far only ASCII
+ * it supports multiple lines (yet to be tested)
+ * you can also insert macros (e.g., current time/date), symbols (e.g., a sun) and cartoons
+ * the specials are preceded by a caret following the respective character
+ * then, there is an extended charset that supports a small subset of UTF-16 (yes, that's right, it's not just UTF-8)
+ * it can further contain information that should be used from their occurrence on
+ * the formatting escape sequences are prefixed by a literal backspace following a char that represents the format
+ * brightness is \<ab>, speed is Y<1-8>, "stay time" is \Z<1-8>, font type is \[A-X]
+ * new lines are introduced by a single \r, the end of the message is marked by three of them
+ *
+ * default formatting:
+ *   - method: cyclic
+ *   - font type: 7x6
+ *   - speed: 5
+ *   - stay time: 4
+ *   - brightness: bright
+ */
+void sendTextToSign(
+    const String &text,
+    const Method method = Method::Cyclic,
+    const FontType fontType = FontType::Font7x6Default,
+    const int speed = 5,
+    const int stayTime = 4,
+    const Brightness brightness = Brightness::Bright
+) {
+    if (speed < 0 || speed > 8) {
+        Serial.println("Invalid speed: " + String(speed, DEC));
+        return;
+    }
+    if (stayTime < 0 || stayTime > 8) {
+        Serial.println("Invalid stayTime: " + String(stayTime, DEC));
+        return;
+    }
+
+    Serial.println("Sending text: \"" + text + "\"");
+
+    String translatedText = convertToCP437(text);
+
+    String toSend = "~" + String(SIGN_ADDRESS, DEC) + "~f01" + (char) method + "\\" + (char) brightness + "\\Y" + String(speed, DEC) + "\\Z" + String(stayTime, DEC) + "\\" + (char) fontType + translatedText + "\r\r\r";
+
+    Serial1.print(toSend);
+
+    Serial.println("Text sent to device: " + toSend);
+    Serial.println("Hex dump: " + hexDump(toSend));
 }

src/webserver.h

@@ -28,11 +28,6 @@ namespace {
                     <input type="text" name="text">
                 </div>
 
-                <div>
-                    <label for="bright">Bright mode</label>
-                    <input type="checkbox" name="bright">
-                </div>
-
                 <div>
                     <button>Send</button>
                 </div>
@@ -45,7 +40,14 @@ namespace {
     }
 
     void handleFormSend() {
-        sendTextToSign("HELLO FORM");
+        String text = webServer.arg("text");
+
+        if (text.isEmpty()) {
+            webServer.send(404, "text/plain", "empty text");
+            return;
+        }
+
+        sendTextToSign(text);
 
         // redirect back to root page
         webServer.sendHeader("Location", "/");
@@ -54,7 +56,29 @@ namespace {
 
     // RESTful API endpoint -- returns a proper status code rather than a redirect
     void handleApiSend() {
-        sendTextToSign("HELLO API");
+        String text = webServer.arg("text");
+
+        if (text.isEmpty()) {
+            webServer.send(404, "text/plain", "empty text");
+            return;
+        }
+
+        sendTextToSign(text);
+        webServer.send(200, "text/plain", "ok");
+    }
+
+    // RESTful API endpoint -- returns a proper status code rather than a redirect
+    void handleRawApiSend() {
+        String toSend = webServer.arg("plain");
+
+        if (toSend.isEmpty()) {
+            webServer.send(404, "text/plain", "empty body");
+            return;
+        }
+
+        Serial.println("Raw message sent to device: " + toSend);
+        Serial.println("Hex dump: " + hexDump(toSend));
+        Serial1.print(toSend);
         webServer.send(200, "text/plain", "ok");
     }
 }
@@ -65,4 +89,5 @@ void configureWebServer() {
     webServer.on("/", HTTPMethod::HTTP_GET, handleIndex);
     webServer.on("/", HTTPMethod::HTTP_POST, handleFormSend);
     webServer.on("/send", HTTPMethod::HTTP_POST, handleApiSend);
+    webServer.on("/raw", HTTPMethod::HTTP_POST, handleRawApiSend);
 }

tools/re-server.py

@@ -0,0 +1,42 @@
+"""
+Simple socket server used to reverse engineer the messaging protocol the bundled software uses to send data to the
+LED sign.
+
+The server just dumps incoming messages in a hexdump-like format as well as an easy to read Python bytestring.
+"""
+
+
+import asyncio
+import string
+
+
+async def handle_client(reader, writer):
+    message = await reader.read(255)
+
+    hex_chars = [hex(j)[2:].zfill(2) for j in message]
+
+    ascii_chars = []
+    for j in message:
+        char = chr(j)
+        if char in (string.ascii_letters + string.digits + string.punctuation):
+            ascii_chars.append(char)
+        else:
+            ascii_chars.append(".")
+
+    print("Message received: ", end="")
+    print(" ".join(hex_chars), end=" | ")
+    print("".join(ascii_chars), end=" | ")
+    print("".join(repr(message)))
+
+    writer.close()
+
+
+async def run_server():
+    server = await asyncio.start_server(handle_client, '', 3000)
+    async with server:
+        await server.serve_forever()
+
+
+if __name__ == "__main__":
+    asyncio.run(run_server())
+