Added I/O expander MCP23008 module and two examples: digital output with LEDS, and digital input with buttons.
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AllAboutEE
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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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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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gpio0, gpio2 = 3, 4
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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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---
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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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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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tmr.alarm(0,2000,1,showButtons) -- run showButtons() every 2 seconds
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---
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-- @description Shows control of 8 GPIO pins/LEDs via I2C with the MCP23008 I/O expander.
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-- Tested on odeMCU 0.9.5 build 20150213.
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-- @date March 02, 2015
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-- @circuit Connect 8 LEDs withs resistors to the GPIO pins of the MCP23008.
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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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-- Connect two 4.7k pull-up resistors on SDA and SCL
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-- Use 3.3V for VCC.
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-- @author Miguel (AllAboutEE)
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-- GitHub: https://github.com/AllAboutEE
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-- Working Example Video: https://www.youtube.com/watch?v=KphAJMZZed0
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-- Website: http://AllAboutEE.com
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---------------------------------------------------------------------------------------------
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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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gpio0, gpio2 = 3, 4
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-- Setup MCP23008
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mcp23008.begin(0x0,gpio2,gpio0,i2c.SLOW)
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mcp23008.writeIODIR(0x00) -- make all GPIO pins as outputs
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mcp23008.writeGPIO(0x00) -- make all GIPO pins off/low
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---
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-- @name count()
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-- @description Reads the value from the GPIO register, increases the read value by 1
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-- and writes it back so the LEDs will display a binary count up to 255 or 0xFF in hex.
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local function count()
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local gpio = 0x00
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gpio = mcp23008.readGPIO()
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if(gpio<0xff) then
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mcp23008.writeGPIO(gpio+1)
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else
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mcp23008.writeGPIO(0x00)
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end
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end
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-- Run count() every 100ms
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tmr.alarm(0,100,1,count)
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---
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-- @description Expands the ESP8266's GPIO to 8 more I/O pins via I2C with the MCP23008 I/O Expander
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-- MCP23008 Datasheet: http://ww1.microchip.com/downloads/en/DeviceDoc/21919e.pdf
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-- Tested on NodeMCU 0.9.5 build 20150213.
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-- @date March 02, 2015
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-- @author Miguel
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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 moduleName = ...
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local M = {}
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_G[moduleName] = M
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-- Constant device address.
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local MCP23008_ADDRESS = 0x20
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-- Registers' address as defined in the MCP23008's datashseet
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local MCP23008_IODIR = 0x00
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local MCP23008_IPOL = 0x01
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local MCP23008_GPINTEN = 0x02
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local MCP23008_DEFVAL = 0x03
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local MCP23008_INTCON = 0x04
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local MCP23008_IOCON = 0x05
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local MCP23008_GPPU = 0x06
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local MCP23008_INTF = 0x07
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local MCP23008_INTCAP = 0x08
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local MCP23008_GPIO = 0x09
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local MCP23008_OLAT = 0x0A
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-- Default value for i2c communication
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local id = 0
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-- pin modes for I/O direction
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M.INPUT = 1
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M.OUTPUT = 0
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-- pin states for I/O i.e. on/off
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M.HIGH = 1
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M.LOW = 0
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-- Weak pull-up resistor state
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M.ENABLE = 1
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M.DISABLE = 0
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---
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-- @name write
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-- @description Writes one byte to a register
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-- @param registerAddress The register where we'll write data
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-- @param data The data to write to the register
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-- @return void
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----------------------------------------------------------
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local function write(registerAddress, data)
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i2c.start(id)
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i2c.address(id,MCP23008_ADDRESS,i2c.TRANSMITTER) -- send MCP's address and write bit
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i2c.write(id,registerAddress)
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i2c.write(id,data)
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i2c.stop(id)
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end
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---
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-- @name read
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-- @description Reads the value of a regsiter
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-- @param registerAddress The reigster address from which to read
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-- @return The byte stored in the register
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----------------------------------------------------------
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local function read(registerAddress)
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-- Tell the MCP which register you want to read from
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i2c.start(id)
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i2c.address(id,MCP23008_ADDRESS,i2c.TRANSMITTER) -- send MCP's address and write bit
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i2c.write(id,registerAddress)
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i2c.stop(id)
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i2c.start(id)
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-- Read the data form the register
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i2c.address(id,MCP23008_ADDRESS,i2c.RECEIVER) -- send the MCP's address and read bit
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local data = 0x00
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data = i2c.read(id,1) -- we expect only one byte of data
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i2c.stop(id)
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return string.byte(data) -- i2c.read returns a string so we convert to it's int value
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end
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---
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--! @name begin
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--! @description Sets the MCP23008 device address's last three bits.
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-- Note: The address is defined as binary 0100[A2][A1][A0] where
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-- A2, A1, and A0 are defined by the connection of the pins,
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-- e.g. if the pins are connected all to GND then the paramter address
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-- will need to be 0x0.
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-- @param address The 3 least significant bits (LSB) of the address
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-- @param pinSDA The pin to use for SDA
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-- @param pinSCL The pin to use for SCL
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-- @param speed The speed of the I2C signal
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-- @return void
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---------------------------------------------------------------------------
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function M.begin(address,pinSDA,pinSCL,speed)
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MCP23008_ADDRESS = bit.bor(MCP23008_ADDRESS,address)
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i2c.setup(id,pinSDA,pinSCL,speed)
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end
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---
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-- @name writeGPIO
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-- @description Writes a byte of data to the GPIO register
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-- @param dataByte The byte of data to write
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-- @return void
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----------------------------------------------------------
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function M.writeGPIO(dataByte)
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write(MCP23008_GPIO,dataByte)
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end
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---
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-- @name readGPIO
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-- @description reads a byte of data from the GPIO register
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-- @return One byte of data
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----------------------------------------------------------
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function M.readGPIO()
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return read(MCP23008_GPIO)
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end
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---
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-- @name writeIODIR
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-- @description Writes one byte of data to the IODIR register
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-- @param dataByte The byte of data to write
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-- @return void
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----------------------------------------------------------
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function M.writeIODIR(dataByte)
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write(MCP23008_IODIR,dataByte)
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end
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---
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-- @name readIODIR
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-- @description Reads a byte from the IODIR register
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-- @return The byte of data in IODIR
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----------------------------------------------------------
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function M.readIODIR()
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return read(MCP23008_IODIR)
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end
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---
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-- @name writeGPPU The byte to write to the GPPU
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-- @description Writes a byte of data to the
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-- PULL-UP RESISTOR CONFIGURATION (GPPU)REGISTER
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-- @param databyte the value to write to the GPPU register.
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-- each bit in this byte is assigned to an individual GPIO pin
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-- @return void
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----------------------------------------------------------------
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function M.writeGPPU(dataByte)
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write(MCP23008_GPPU,dataByte)
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end
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---
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-- @name readGPPU
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-- @description Reads the GPPU (Pull-UP resistors register) byte
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-- @return The GPPU byte i.e. state of all internal pull-up resistors
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-------------------------------------------------------------------
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function M.readGPPU()
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return read(MCP23008_GPPU)
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end
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return M
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