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   "source": [
    "オリジナルの作成: 2014/12/21"
   ]
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   "source": [
    "# 09-７セグメントLEDを使ってみる\n",
    "数字（＋アルファベット一部）を表示できる７セグメントLEDを使ってみましょう。"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## ブレッドボードを組み立てる\n",
    "7セグメントLEDをつないでみましょう。\n",
    "\n",
    "必要な部品は、以下の通りです。\n",
    "- Arduino （今回はArduino Pro Miniを使います）\n",
    "- 7セグメントLED（C-551SR）１個（カソード共通タイプです）\n",
    "- トランジスター（2SC1815）１個\n",
    "- 抵抗（4.7KΩ）１個\n",
    "\n",
    "部品が揃ったら、以下の様につないで下さい。\n",
    "\n",
    "<img src=\"images/09/7SegmentLED_brd.png\" width=\"450\">"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 7セグメントのピン配置\n",
    "７セグメントのピンの配置 \n",
    "<a href=\"#Ref_1\">1</a>\n",
    "は、以下の様になっています。\n",
    "\n",
    "<img src=\"images/09/C-551SR_pin.png\">\n",
    "\n",
    "C-551SRは、以下の様にカソードを共通とするタイプです。\n",
    "\n",
    "<img src=\"images/09/C551X.png\">"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 2SC1815のピン配置\n",
    "トランジスターは、7セグメントLEDをArduinoで駆動するための電流を供給するのと、 出力タイミングを制御するために使用します。 使用するトランジスターはよく使われる2SC1815です。\n",
    "\n",
    "2SC1815のデータシートで、ピンの設定を確認します。下の図は、下から見たピンの位置です。\n",
    "\n",
    "<img src=\"images/09/2SC1815_pin.png\">\n",
    "\n",
    "セレクターとベース間の抵抗は、7セグメントLEDの各LEDに10mAを供給すると70mAが必要となりので、\n",
    "\n",
    "$$\n",
    "ベース電流 = \\frac{5V - 0.6V}{4.7KΩ} = 0.9mA\n",
    "$$\n",
    "\n",
    "これから増幅率hf = 100として、以下の関係から90mAと十分な電流を供給できます。\n",
    "\n",
    "$$\n",
    "コレクター電流 = ベース電流*hf = 0.9 \\times 100 = 90mA\n",
    "$$\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## スケッチで動作確認\n",
    "できたブレッドボードの回路を以下のスケッチで動かしてみます。\n",
    "\n",
    "```C++\n",
    "int  a = 11;\n",
    "int  b = 10;\n",
    "int  c = 8;\n",
    "int  d = 7;\n",
    "int  e = 6;\n",
    "int  f = 5;\n",
    "int  g = 4;\n",
    "\n",
    "int  leds[] = { a, b, c, d, e, f, g};\n",
    "int  sel = 12;\n",
    "\n",
    "int  ptrn[][7] = {\n",
    "  {1,1,1,1,1,1,0},\n",
    "  {0,1,1,0,0,0,0},\n",
    "  {1,1,0,1,1,0,1},\n",
    "  {1,1,1,1,0,0,1},\n",
    "  {0,1,1,0,0,1,1},\n",
    "  {1,0,1,1,0,1,1},\n",
    "  {1,0,1,1,1,1,1},\n",
    "  {1,1,1,0,0,0,0},\n",
    "  {1,1,1,1,1,1,1},\n",
    "  {1,1,1,0,0,1,1},\n",
    "  {1,1,1,0,1,1,1},\n",
    "  {0,0,1,1,1,1,1},\n",
    "  {1,0,0,1,1,1,0}, \n",
    "  {0,1,1,1,1,0,1},\n",
    "  {1,0,0,1,1,1,1},\n",
    "  {1,0,0,0,1,1,1},\n",
    "  {0,0,0,0,0,0,0}\n",
    "};\n",
    "\n",
    "void setup() {\n",
    "  pinMode(sel, OUTPUT);\n",
    "  pinMode(a, OUTPUT);\n",
    "  pinMode(b, OUTPUT);\n",
    "  pinMode(c, OUTPUT);\n",
    "  pinMode(d, OUTPUT);\n",
    "  pinMode(e, OUTPUT);\n",
    "  pinMode(f, OUTPUT);\n",
    "  pinMode(g, OUTPUT);\n",
    "\n",
    "  digitalWrite(sel, HIGH); \n",
    "}\n",
    "\n",
    "void loop() {\n",
    "  for (int i = 0; i < 17; i++) {\n",
    "    for (int j = 0; j < 7; j++) {\n",
    "      digitalWrite(leds[j], ptrn[i][j]); \n",
    "    }\n",
    "    delay(1000);\n",
    "  }\n",
    "}\n",
    "```\n",
    "\n",
    "上手くできていたら、以下の様に０〜Fと全て消灯を１秒間隔で切り替えて表示します。\n",
    "\n",
    "<img src=\"images/09/7SegementLED_setting.png\" width=\"450\">"
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