draft

HCHO.js

@@ -1,13 +1,34 @@
+const assert       = require('assert');
 const SerialPort   = require('serialport');
 const createReader = require('./reader');
 
+function parse(buffer){
+  const data = {
+    HEAD    : buffer.readUInt16BE(0),
+    LENGTH  : buffer.readUIntBE(2),
+    TYPE    : buffer.readUIntBE(3),
+    UNIT    : buffer.readUIntBE(4),
+    VH      : buffer.readUIntBE(5),
+    VALUE   : buffer.readUInt16BE(6),
+    CHECKSUM: buffer.readUInt16BE(8),
+  };
+  var checksum = 0;
+  for(var i=0;i<buffer.length - 2;i++){
+    checksum += buffer[i];
+  }
+  assert.equal(data.HEAD, 0x424d, 'Invalid data header');
+  assert.equal(checksum, data.CHECKSUM, 'Checksum error');
+  return data;
+}
+
 class HCHO extends SerialPort {
   constructor(dev){
     super(dev);
     const reader = createReader({
       LEN_LENGTH: 1
-    }, message => {
-      console.log(message);
+    }, data => {
+      const message = parse(data);
+      this.emit('message', message);
     });
     this.on('data', reader);
   }

PMS5003.js

@@ -1,15 +1,14 @@
-const fs           = require('fs');
 const assert       = require('assert');
-const EventEmitter = require('events');
+const SerialPort   = require('serialport');
 const createReader = require('./reader');
 
 /**
 * parse sensor data
 */
 function parse(buffer){
-  var data = {
-    Head    : buffer.readUInt16BE(00),
-    Length  : buffer.readUInt16BE(02),
+  const data = {
+    HEAD    : buffer.readUInt16BE(00),
+    LENGTH  : buffer.readUInt16BE(02),
     PM1_0   : buffer.readUInt16BE(04),
     PM2_5   : buffer.readUInt16BE(06),
     PM10    : buffer.readUInt16BE(08),
@@ -30,22 +29,20 @@ function parse(buffer){
   for(var i=0;i<buffer.length - 2;i++){
     checksum += buffer[i];
   }
-  assert.equal(data.Head, 0x424d, 'Invalid data header');
+  assert.equal(data.HEAD, 0x424d, 'Invalid data header');
   assert.equal(checksum, data.CHECKSUM, 'Checksum error');
   return data;
 }
 
 /**
 * DSensor
 */
-class DSensor extends EventEmitter {
+class DSensor extends SerialPort {
   constructor(dev){
-    super();
-    if(typeof dev === 'undefined') dev = process.stdin;
-    if(typeof dev === 'string') dev = fs.createReadStream(dev);
+    super(dev);
     const reader = createReader(data => {
       const message = parse(data);
-      this.emit('data', message);
+      this.emit('message', message);
     });
     dev.on('data', reader);
     return this;

reader.js

@@ -1,39 +1,37 @@
 
-function createReader({ 
-  LEN_HEADER = 2, 
-  LEN_LENGTH = 2,
-  LEN_CHECKSUM = 2
-}, fn){
-  const STATE_HEADER_1 = 0x42;
-  const STATE_HEADER_2 = 0x4d;
-  const STATE_LENGTH   = 2;
-  const STATE_DATA     = 3;
-  var flag = STATE_HEADER_1, index, len, buffer = Buffer.alloc(0);
-  return function(chunk){
+const STATE_HEADER_1 = 0x42;
+const STATE_HEADER_2 = 0x4d;
+const STATE_LENGTH   = 2;
+const STATE_DATA     = 3;
+
+const LEN_HEADER = 2;
+const LEN_CHECKSUM = 2;
+
+function createReader(fn){
+  let state = STATE_HEADER_1, buffer = Buffer.alloc(0), len;
+  return chunk => {
     buffer = Buffer.concat([ buffer, chunk ]);
-    for(var i = 0; i < buffer.length; i++){
-      if(flag === STATE_HEADER_1 && buffer[i] === STATE_HEADER_1){
-        flag = STATE_HEADER_2;
+    for(const i = 0; i < buffer.length; i++){
+      if(state === STATE_HEADER_1 && buffer[i] === STATE_HEADER_1){
+        state = STATE_HEADER_2;
         continue;
       }
-      if(flag === STATE_HEADER_2 && buffer[i] === STATE_HEADER_2){
-        flag = STATE_LENGTH;
-        index = ++i;
+      if(state === STATE_HEADER_2 && buffer[i] === STATE_HEADER_2){
+        state = STATE_LENGTH;
         continue;
       }
-      if(flag === STATE_LENGTH && buffer.length - index >= LEN_LENGTH){
+      if(state === STATE_LENGTH){
         len = buffer.readUInt16BE(index);
-        flag = STATE_DATA;
+        state = STATE_DATA;
         continue;
       }
-      if(flag === STATE_DATA && buffer.length - index >= len + LEN_CHECKSUM){
+      if(state === STATE_DATA){
         fn(buffer.slice(index - LEN_HEADER, index + len + LEN_CHECKSUM));
         buffer = buffer.slice(index + len + LEN_CHECKSUM);
-        flag = STATE_HEADER_1;
+        state = STATE_HEADER_1;
       }
     }
   };
 }
 
-
 module.exports = createReader;