MCP23017 module refactorings to save some heap (#3317)
* mcp23017: functions to metatable Avoids closures for each module. * mcp23017: inline constants Saves nearly half a kilobyte of heap.
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Nathaniel Wesley Filardo
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@ -1,62 +1,40 @@
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--[[
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This Lua module provides access to the MCP23017 module.
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The MCP23017 is a port expander and provides 16 channels for inputs and outputs.
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Up to 8 devices (128 channels) are possible by the configurable address (A0 - A2 Pins).
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The MCP23017 is a port expander and provides 16 channels for inputs and
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outputs. Up to 8 devices (128 channels) are possible by the configurable
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address (A0 - A2 Pins).
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Due to the 16 channels, 2 bytes are required for switching outputs or reading input signals. These are A and B.
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A single pin can be set or a whole byte.
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Due to the 16 channels, 2 bytes are required for switching outputs or
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reading input signals. These are A and B. A single pin can be set or a
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whole byte.
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The numbering of the individual pins starts at 0 and ends with 7.
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The numbers are for each register GPIO A and GPIO B.
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The numbering of the individual pins starts at 0 and ends with 7. The
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numbers are for each register GPIO A and GPIO B.
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The module requires `i2c` and `bit` C module built into firmware.
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For register name <-> number mapping, see the MCP23017 data sheet, table
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3-1 on page 12 (as of Revision C, July 2016). This module uses the
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IOCON.BANK=0 numbering (the default) throughout.
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@author Marcel P. | Plomi.net
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@github https://github.com/plomi-net
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@version 1.0.0
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]]
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local i2c, string, issetBit, setBit, clearBit, error =
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i2c, string, bit.isset, bit.set, bit.clear, error
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local isINPUT, isGPB, isHIGH = true, true, true
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-- registers (not used registers are commented out)
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local MCP23017_IODIRA = 0x00
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local MCP23017_IODIRB = 0x01
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local MCP23017_DEFVALA = 0x06
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local MCP23017_DEFVALB = 0x07
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local MCP23017_GPIOA = 0x12
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local MCP23017_GPIOB = 0x13
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--[[
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local MCP23017_IPOLA = 0x02
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local MCP23017_IPOLB = 0x03
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local MCP23017_GPINTENA = 0x04
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local MCP23017_GPINTENB = 0x05
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local MCP23017_DEFVALA = 0x06
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local MCP23017_DEFVALB = 0x07
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local MCP23017_INTCONA = 0x08
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local MCP23017_INTCONB = 0x09
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local MCP23017_IOCON = 0x0A
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local MCP23017_IOCON2 = 0x0B
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local MCP23017_GPPUA = 0x0C
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local MCP23017_GPPUB = 0x0D
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local MCP23017_INTFA = 0x0E
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local MCP23017_INTFB = 0x0F
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local MCP23017_INTCAPA = 0x10
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local MCP23017_INTCAPB = 0x11
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local MCP23017_OLATA = 0x14
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local MCP23017_OLATB = 0x15
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]]
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local i2c, string, issetBit, setBit, clearBit =
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i2c, string, bit.isset, bit.set, bit.clear
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-- metatable
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local mcp23017 = {
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INPUT = isINPUT,
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OUTPUT = not isINPUT,
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GPA = not isGPB,
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GPB = isGPB,
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HIGH = isHIGH,
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LOW = not isHIGH
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-- convenience parameter enumeration names
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INPUT = true,
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OUTPUT = false,
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GPA = false,
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GPB = true,
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HIGH = true,
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LOW = false
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}
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mcp23017.__index = mcp23017
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@ -98,13 +76,65 @@ local function checkPinIsInRange(pin)
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return pin
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end
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local function reset(address, i2cId)
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writeByte(address, i2cId, MCP23017_IODIRA, 0xFF)
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writeByte(address, i2cId, MCP23017_IODIRB, 0xFF)
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function mcp23017:writeIODIR(bReg, newByte)
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writeByte(self.address, self.i2cId,
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bReg and 0x1 --[[IODIRB register]] or 0x0 --[[IODIRA register]], newByte)
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end
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-- setup device
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local function setup(address, i2cId)
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function mcp23017:writeGPIO(bReg, newByte)
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writeByte(self.address, self.i2cId,
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bReg and 0x13 --[[GPIOB register]] or 0x12 --[[GPIOA register]], newByte)
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end
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function mcp23017:readGPIO(bReg)
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return readByte(self.address, self.i2cId,
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bReg and 0x13 --[[GPIOB register]] or 0x12 --[[GPIOA register]])
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end
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-- read pin input
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function mcp23017:getPinState(bReg, pin)
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return issetBit(readByte(self.address, self.i2cId,
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bReg and 0x13 --[[GPIOB register]] or 0x12 --[[GPIOA register]]),
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checkPinIsInRange(pin))
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end
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-- set pin to low or high
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function mcp23017:setPin(bReg, pin, state)
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local a, i = self.address, self.i2cId
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local inReq = bReg and 0x13 --[[GPIOB register]] or 0x12 --[[GPIOA register]]
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local inPin = checkPinIsInRange(pin)
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local response = readByte(a, i, inReq)
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writeByte(a, i, inReq,
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state and setBit(response, inPin) or clearBit(response, inPin))
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return true
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end
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-- set mode for a pin
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function mcp23017:setMode(bReg, pin, mode)
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local a, i = self.address, self.i2cId
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local inReq = bReg and 0x1 --[[IODIRB register]] or 0x0 --[[IODIRA register]]
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local inPin = checkPinIsInRange(pin)
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local response = readByte(a, i, inReq)
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writeByte(a, i, inReq,
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mode and setBit(response, inPin) or clearBit(response, inPin))
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return true
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end
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-- reset gpio mode
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function mcp23017:reset()
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local a, i = self.address, self.i2cId
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writeByte(a, i, 0x0 --[[IODIRA register]], 0xFF)
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writeByte(a, i, 0x1 --[[IODIRB register]], 0xFF)
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end
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-- setup internal pullup
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function mcp23017:setInternalPullUp(bReg, iByte)
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writeByte(self.address, self.i2cId,
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bReg and 0x7 --[[DEFVALB register]] or 0x6 --[[DEFVALA register]], iByte)
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end
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return function(address, i2cId)
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local self = setmetatable({}, mcp23017)
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-- check device address (0x20 to 0x27)
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if (address < 32 or address > 39) then
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@ -113,73 +143,13 @@ local function setup(address, i2cId)
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if (checkDevice(address, i2cId) ~= true) then
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error("MCP23017 device on " .. string.format('0x%02X', address) .. " not found")
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else
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reset(address, i2cId)
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return 1
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end
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end
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return function(address, i2cId)
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local self = setmetatable({}, mcp23017)
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if setup(address, i2cId) then
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self.writeIODIR = function(sf, bReg, newByte) -- luacheck: no unused
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writeByte(address, i2cId,
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bReg == isGPB and MCP23017_IODIRB or MCP23017_IODIRA,
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newByte)
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end
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self.writeGPIO = function(sf, bReg, newByte) -- luacheck: no unused
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writeByte(address, i2cId,
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bReg == isGPB and MCP23017_GPIOB or MCP23017_GPIOA, newByte)
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end
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self.readGPIO = function(sf, bReg) -- luacheck: no unused
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return readByte(address, i2cId, -- upvals
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bReg == isGPB and MCP23017_GPIOB or MCP23017_GPIOA)
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end
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-- read pin input
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self.getPinState = function(sf, bReg, pin) -- luacheck: no unused
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return issetBit(readByte(address, i2cId,
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bReg == isGPB and MCP23017_GPIOB or MCP23017_GPIOA),
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checkPinIsInRange(pin))
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end
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-- set pin to low or high
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self.setPin = function(sf, bReg, pin, state) -- luacheck: no unused
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local inReq = bReg == isGPB and MCP23017_GPIOB or MCP23017_GPIOA
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local inPin = checkPinIsInRange(pin)
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local response = readByte(address, i2cId, inReq)
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writeByte(address, i2cId, inReq,
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state == isHIGH and setBit(response, inPin) or clearBit(response, inPin))
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return true
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end
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-- set mode for a pin
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self.setMode = function(sf, bReg, pin, mode) -- luacheck: no unused
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local inReq = bReg == isGPB and MCP23017_IODIRB or MCP23017_IODIRA
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local inPin = checkPinIsInRange(pin)
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local response = readByte(address, i2cId, inReq)
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writeByte(address, i2cId, inReq,
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mode == isINPUT and setBit(response, inPin) or clearBit(response, inPin))
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return true
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end
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-- reset gpio mode
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self.reset = function(sf) -- luacheck: no unused
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reset(address, i2cId)
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end
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-- setup internal pullup
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self.setInternalPullUp = function(sf, bReg, iByte) -- luacheck: no unused
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writeByte(address, i2cId,
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bReg == isGPB and MCP23017_DEFVALB or MCP23017_DEFVALA, iByte)
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end
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self.address = address
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self.i2cId = i2cId
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self:reset()
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return self
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end
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return nil
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end
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