Stock Price Dial

A physical stock price indicator using an ESP8266 and a servo motor. The dial moves to indicate the current stock price of any configured stock ticker.

Hardware Requirements

• ESP8266 board
• Servo motor (tested with standard SG90)
• Power supply
• Dial or pointer attachment for servo

Pin Configuration

• Servo signal: GPIO2
• Servo power: 3.3V
• Servo ground: GND

Initial Setup

1. Install PlatformIO
2. Clone this repository
3. Copy configuration template:

   cd stock_dial/src
   cp env.template.h env.h

4. Edit src/env.h with your credentials:
   • WiFi SSID and password
   • Alpha Vantage API key (see API Setup below)

API Setup and Limitations

This project uses Alpha Vantage for stock price data.

1. Get a free API key at: https://www.alphavantage.co/support/#api-key

2. Free tier limitations:

   • 25 API calls per day maximum
   • 5 API calls per minute

3. To stay safely within these limits, the project:

   • Fetches prices every 80 minutes (18 calls per day)
   • Leaves 7 daily calls as buffer for:
     • Power cycles
     • Network retries
     • System restarts
   • Limits retry attempts to 2 per failed call
   • Caches the last known price if API call fails

Note: If you need more frequent updates, Alpha Vantage offers paid plans:

• Premium: 120 API calls per minute
• Enterprise: 600+ API calls per minute

Configuration

• Stock settings in src/config.cpp:
  • Ticker symbol
  • Price range (min/max for servo movement)
  • Update interval (default: 80 minutes)
• Hardware settings in src/config.cpp:
  • Servo pin
  • Pulse width range
  • Movement delays

Build and Upload

1. Connect your ESP8266
2. Update port in platformio.ini if needed
3. Build and upload using PlatformIO

Troubleshooting

• If you see "Invalid API call" errors, verify your API key
• If you see "Exceeded API call frequency" errors:
  • The 80-minute interval should prevent this
  • If it occurs, it might indicate clock drift or multiple resets
  • Consider increasing the interval or upgrading your API plan
• The servo will retain its last position if API calls fail
• The system includes 2 retry attempts for failed API calls, with a 10-second delay between attempts

License

MIT License