Wireless Analog Terminal Bell using M5Stick-C

ESP32_http_solenoid_driver.ino

#include <WiFi.h>
#include <WebServer.h>

#define OUTPUT_PIN 26

char ssid[] = "YOUR-WIFI-SSID";
char pass[] = "YOUR-WIFI-PASSWORD";
WebServer server(80);

void setup() {
  pinMode(OUTPUT_PIN, OUTPUT);
  digitalWrite(OUTPUT_PIN, LOW);

  Serial.begin(115200);

  WiFi.begin();
  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, pass);
  unsigned long start = millis();
  while (WiFi.status() != WL_CONNECTED && millis() - start < 30000) {
    Serial.print(".");
    delay(1000);
  }
  if (WiFi.status() != WL_CONNECTED) {
    Serial.println("failed to connect WiFi.");
    delay(1000);
    ESP.restart();
  }
  Serial.println(WiFi.localIP());

  server.on("/", []() {
    int wait = 50;
    String wait_s = server.arg("wait");
    if (wait_s != "")
      wait = wait_s.toInt();
    digitalWrite(OUTPUT_PIN, HIGH);
    delay(wait);
    digitalWrite(OUTPUT_PIN, LOW);
    server.send(200, "text/plain", "OK\n");
  });
  server.onNotFound([]{ server.send(404, "text/plain", "Not Found"); });
  server.begin();
}

void loop() {
  server.handleClient();

  if (WiFi.status() != WL_CONNECTED) {
    Serial.println("disconnected.");
    delay(1000);
    ESP.restart();
  }
}

pty-proxy.rb

#!/usr/bin/ruby
require 'pty'
require 'open-uri'

BELL_URL = 'http://192.168.0.123/'  # Change this to your ESP32 address

# Avoid double proxy
if ENV['PTY_PROXY']
  warn "pty-proxy is already active!"
  exec ENV['SHELL']
end
ENV['PTY_PROXY'] = 'ACTIVE'

# Track escape sequences to avoid removing "\a" in them
@esc_seq = 0
@osc_mode = false

# Remove "\a" from buf (unless it is in escape sequences)
def remove_bell(buf)
  buf2 = String.new(capacity: 4096)
  buf.each_char do |c|
    if @esc_seq == 0 && c == "\a"
      Thread.new do
        open(BELL_URL).close rescue nil
      end
    else
      buf2 << c
    end
    if @esc_seq > 0
      @osc_mode = true if @esc_seq == 1 && c == "]"
      if c.match(@osc_mode ? /[\a\x1b]/ : /[^0-9;?\[]/)
        @esc_seq = 0
        @osc_mode = false
      else
        @esc_seq += 1
      end
    elsif c == "\x1b"
      @esc_seq = 1
    end
  end
  buf2
end

# Launch shell in pty
Signal.trap(:CHLD, 'IGNORE')
system "stty raw -echo 2> /dev/null"
size = %x(stty size).split(/\s+/)
p = PTY.spawn %(stty rows #{size[0]} cols #{size[1]}; exec '#{ENV['SHELL']}')

# When window size is changed, notify it to the shell
size_changed = IO.pipe
Signal.trap(:WINCH) do
  size_changed[1].write ' '
end

# Proxy input/output
@buf = String.new(capacity: 4096)
until p[0].closed? || STDIN.closed?
  s = IO.select [p[0], STDIN, size_changed[0]]

  if s[0][0] == size_changed[0]
    size_changed[0].readpartial(4096)
    size = %x(stty size).split(/\s+/)
    system("stty rows #{size[0]} cols #{size[1]}", in: p[0])
    Process.kill :WINCH, p[2]
    next
  end

  while s0 = s[0][0]
    s[0].shift
    out = s0 == STDIN ? out = p[1] : out = STDOUT
    begin
      buf = s0.readpartial(4096, @buf)
      buf = remove_bell(buf) if s0 == p[0]
      out.write buf
      out.flush
    rescue EOFError
      p[0].close
      p[1].close

      system "stty -raw 2> /dev/null"
      exit
    end
  end
end