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- ---
- -- @description Shows control of 8 GPIO pins/LEDs via I2C with the MCP23008 I/O expander.
- -- Tested on odeMCU 0.9.5 build 20150213.
- -- @date March 02, 2015
- -- @circuit Connect 8 LEDs withs resistors to the GPIO pins of the MCP23008.
- -- Connect GPIO0 of the ESP8266-01 module to the SCL pin of the MCP23008.
- -- Connect GPIO2 of the ESP8266-01 module to the SDA pin of the MCP23008.
- -- Connect two 4.7k pull-up resistors on SDA and SCL
- -- Use 3.3V for VCC.
- -- @author Miguel (AllAboutEE)
- -- GitHub: https://github.com/AllAboutEE
- -- Working Example Video: https://www.youtube.com/watch?v=KphAJMZZed0
- -- Website: http://AllAboutEE.com
- ---------------------------------------------------------------------------------------------
- local mcp23008 = require ("mcp23008")
- -- ESP-01 GPIO Mapping as per GPIO Table in https://github.com/nodemcu/nodemcu-firmware
- local gpio0, gpio2 = 3, 4
- ---
- -- @name count()
- -- @description Reads the value from the GPIO register, increases the read value by 1
- -- and writes it back so the LEDs will display a binary count up to 255 or 0xFF in hex.
- local function count()
- local gpio = mcp23008.readGPIO()
- if(gpio<0xff) then
- mcp23008.writeGPIO(gpio+1)
- else
- mcp23008.writeGPIO(0x00)
- end
- end
- do
- -- Setup MCP23008
- mcp23008.begin(0x0,gpio2,gpio0,i2c.SLOW)
- mcp23008.writeIODIR(0x00) -- make all GPIO pins as outputs
- mcp23008.writeGPIO(0x00) -- make all GIPO pins off/low
- -- Run count() every 100ms
- tmr.create():alarm(100, tmr.ALARM_AUTO, count)
- end
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