58 lines
1.8 KiB
Lua
58 lines
1.8 KiB
Lua
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---
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-- @description Shows how to read 8 GPIO pins/buttons via I2C with the MCP23008 I/O expander.
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-- Tested on NodeMCU 0.9.5 build 20150213.
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-- @circuit
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-- Connect GPIO0 of the ESP8266-01 module to the SCL pin of the MCP23008.
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-- Connect GPIO2 of the ESP8266-01 module to the SDA pin of the MCP23008.
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-- Use 3.3V for VCC.
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-- Connect switches or buttons to the GPIOs of the MCP23008 and GND.
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-- Connect two 4.7k pull-up resistors on SDA and SCL
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-- We will enable the internal pull up resistors for the GPIOS of the MCP23008.
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-- @author Miguel (AllAboutEE)
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-- GitHub: https://github.com/AllAboutEE
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-- YouTube: https://www.youtube.com/user/AllAboutEE
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-- Website: http://AllAboutEE.com
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---------------------------------------------------------------------------------------------
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local mcp23008 = require ("mcp23008")
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-- ESP-01 GPIO Mapping as per GPIO Table in https://github.com/nodemcu/nodemcu-firmware
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local gpio0, gpio2 = 3, 4
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---
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-- @name showButtons
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-- @description Shows the state of each GPIO pin
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-- @return void
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---------------------------------------------------------
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local function showButtons()
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local gpio = mcp23008.readGPIO() -- read the GPIO/buttons states
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-- get/extract the state of one pin at a time
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for pin=0,7 do
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local pinState = bit.band(bit.rshift(gpio,pin),0x1) -- extract one pin state
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-- change to string state (HIGH, LOW) instead of 1 or 0 respectively
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if(pinState == mcp23008.HIGH) then
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pinState = "HIGH"
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else
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pinState = "LOW"
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end
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print("Pin ".. pin .. ": ".. pinState)
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end
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print("\r\n")
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end
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do
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-- Setup the MCP23008
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mcp23008.begin(0x0,gpio2,gpio0,i2c.SLOW)
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mcp23008.writeIODIR(0xff)
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mcp23008.writeGPPU(0xff)
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tmr.create():alarm(2000, tmr.ALARM_AUTO, showButtons) -- run showButtons() every 2 seconds
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end
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