#!/usr/bin/env python
"""MCP230XX, python module for the MCP230008 and MCP230017 GPIO
expander chips
created September 9, 2017
last modified October 8, 2017"""
"""
Copyright 2017 Owain Martin
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
"""
import time, sys, smbus
class MCP230XX:
def __init__(self, chip, i2cAddress, regScheme = '16bit'):
self.i2cAddress = i2cAddress
self.bus =smbus.SMBus(1)
self.chip = chip
if self.chip == 'MCP23008':
self.bank = '8bit'
else:
self.bank = regScheme
self.callBackFuncts=[]
for i in range(0,17):
self.callBackFuncts.append(['empty','emtpy'])
return
def single_access_read(self, reg=0x00):
"""single_access_read, function to read a single data register
of the MCP230xx gpio expander"""
dataTransfer=self.bus.read_byte_data(self.i2cAddress,reg)
return dataTransfer
def single_access_write(self, reg=0x00, regValue=0x0):
"""single_access_write, function to write to a single data register
of the MCP230xx gpio expander"""
self.bus.write_byte_data(self.i2cAddress, reg, regValue)
return
def register_bit_select(self, pin, reg8A, reg16A, reg8B, reg16B):
"""register_bit_select, function to return the proper
register and bit position to use for a particular GPIO
and GPIO function"""
# need to add way of throwing an error if pin is outside
# of 0-15 range
if pin >= 0 and pin < 8:
bit = pin
if self.bank == '16bit':
reg = reg16A
else: # self.bank = '8bit'
reg = reg8A
elif pin >= 8 and pin <16:
bit = pin - 8
if self.bank == '16bit':
reg = reg16B
else: # self.bank = '8bit'
reg = reg8B
return reg, bit
def interrupt_options(self, outputType = 'activehigh', bankControl = 'separate'):
"""interrupt_options, function to set the options for the 2 interrupt
pins"""
if self.bank == '16bit':
reg = 0x0A
else: # self.bank = '8bit'
reg = 0x05
if outputType == 'activelow':
odrBit = 0
intpolBit = 0
elif outputType == 'opendrain':
odrBit = 1
intpolBit = 0
else: # outputType = 'activehigh'
odrBit = 0
intpolBit = 1
if bankControl == 'both':
mirrorBit = 1
else: # bankControl = 'separate'
mirrorBit = 0
regValue = self.single_access_read(reg)
regValue = regValue & 0b10111001
regValue = regValue | (mirrorBit<<6) + (odrBit<<2) + (intpolBit<<1)
self.single_access_write(reg, regValue)
return
def set_register_addressing(self, regScheme='8bit'):
"""set_register_addressing, function to change how the registers
are mapped. For an MCP23008, bank should always equal '8bit'. This
sets bit 7 of the IOCON register"""
if self.bank == '16bit':
reg = 0x0A
else: # self.bank = '8bit'
reg = 0x05
if regScheme == '16bit':
bankBit = 0
self.bank = '16bit'
else: # regScheme = '8bit'
bankBit = 1
self.bank = '8bit'
regValue = self.single_access_read(reg)
regValue = regValue & 0b01111111
regValue = regValue | (bankBit<<7)
self.single_access_write(reg, regValue)
return
def set_mode(self, pin, mode, pullUp='disable'):
"""set_mode, function to set up a GPIO pin to either an input
or output. The input pullup resistor can also be enabled.
This sets the appropriate bits in the IODIRA/B and GPPUA/B
registers"""
# GPIO direction set up section
reg, bit = self.register_bit_select(pin ,reg8A=0x00,reg16A=0x00,
reg8B=0x10, reg16B=0x01)
regValue = self.single_access_read(reg)
if mode == 'output':
mask = 0b11111111 & ~(1<<bit)
regValue = regValue & mask
self.single_access_write(reg, regValue)
else: # mode = input
mask = 0x00 | (1<<bit)
regValue = regValue | mask
self.single_access_write(reg, regValue)
# pullUp enable/disable section
if mode == 'input':
reg, bit = self.register_bit_select(pin ,reg8A=0x06,reg16A=0x0C,
reg8B=0x16, reg16B=0x0D)
regValue = self.single_access_read(reg)
if pullUp == 'enable':
mask = 0x00 | (1<<bit)
regValue = regValue | mask
self.single_access_write(reg, regValue)
else: # pullUp = disable
mask = 0b11111111 & ~(1<<bit)
regValue = regValue & mask
self.single_access_write(reg, regValue)
return
def invert_input(self, pin, invert = False):
"""invert_input, function to invert the output of the pins
corresponding GPIO register bit. Sets bit in IPOLA/B"""
# input invert on/off section
reg, bit = self.register_bit_select(pin ,reg8A=0x01,reg16A=0x02,
reg8B=0x11, reg16B=0x03)
regValue = self.single_access_read(reg)
if invert == True:
mask = 0x00 | (1<<bit)
regValue = regValue | mask
self.single_access_write(reg, regValue)
else: # invert = False
mask = 0b11111111 & ~(1<<bit)
regValue = regValue & mask
self.single_access_write(reg, regValue)
return
def output(self, pin, value):
"""output, function to set the state of a GPIO output
pin via the appropriate bit in the OLATA/B registers"""
reg, bit = self.register_bit_select(pin ,reg8A=0x0A,reg16A=0X14,
reg8B=0X1A, reg16B=0x15)
regValue = self.single_access_read(reg)
if value == 1:
# set output high
mask = 0x00 | (1<<bit)
regValue = regValue | mask
else:
# set output low
mask = 0b11111111 & ~(1<<bit)
regValue = regValue & mask
self.single_access_write(reg, regValue)
return
def input(self, pin):
"""input, function to get the current level of a GPIO input
pin by reading the appropriate bit in the GPIOA/B registers"""
reg, bit = self.register_bit_select(pin ,reg8A=0x09,reg16A=0X12,
reg8B=0X19, reg16B=0x13)
regValue = self.single_access_read(reg)
mask = 0x00 | (1<<bit)
value = regValue & mask
value = value >> bit
return value
def input_at_interrupt(self, pin):
"""input_at_interrupt, function to get the current level of a GPIO input
pin when an interrupt has occurred by reading the appropriate bit in the
INTCAPA/B registers"""
reg, bit = self.register_bit_select(pin ,reg8A=0x08,reg16A=0X10,
reg8B=0X18, reg16B=0x11)
regValue = self.single_access_read(reg)
mask = 0x00 | (1<<bit)
value = regValue & mask
value = value >> bit
return value
def add_interrupt(self, pin, callbackFunctLow='empty', callbackFunctHigh='empty'):
"""add_interrupt, function to set up the interrupt options
for a specific GPIO including callback functions to be executed
when an interrupt occurs"""
# set bit in GPINTENA/B registers
reg, bit = self.register_bit_select(pin ,reg8A=0x02,reg16A=0X04,
reg8B=0X12, reg16B=0x05)
regValue = self.single_access_read(reg)
mask = 0x00 | (1<<bit)
regValue = regValue | mask
self.single_access_write(reg, regValue)
# set bit in INTCONA/B registers
reg, bit = self.register_bit_select(pin ,reg8A=0x04,reg16A=0X08,
reg8B=0X14, reg16B=0x09)
regValue = self.single_access_read(reg)
mask = 0b11111111 & ~(1<<bit)
regValue = regValue & mask
self.single_access_write(reg, regValue)
# set bit in DEFVALA/B registers - not required
# set call back functions in function list
self.callBackFuncts[pin][0]=callbackFunctLow
self.callBackFuncts[pin][1]=callbackFunctHigh
return
def remove_interrupt(self, pin):
"""remove_interrupt, function to remove the interrupt settings
from an MCP230xx pin"""
# set bit in GPINTENA/B registers
reg, bit = self.register_bit_select(pin ,reg8A=0x02,reg16A=0X04,
reg8B=0X12, reg16B=0x05)
regValue = self.single_access_read(reg)
mask = 0b11111111 & ~(1<<bit)
regValue = regValue & mask
self.single_access_write(reg, regValue)
# reset call back functions in function list to 'empty'
self.callBackFuncts[pin][0]='empty'
self.callBackFuncts[pin][1]='empty'
return
def callbackA(self, gpio):
"""function called by RPI.GPIO on an bank A interrupt condition.
This function will figure out which MCP230xx pin caused the
interrupt and initiate the appropriate callback function"""
# read INTF register
if self.bank == '16bit':
reg = 0x0E
else: # self.bank = '8bit'
reg = 0x07
regValue = self.single_access_read(reg)
pin = -1
for i in range(0,8):
if regValue == (1<<i):
pin = i
break
value = self.input_at_interrupt(pin)
if self.callBackFuncts[pin][value] != 'empty':
self.callBackFuncts[pin][value](pin)
return
def callbackB(self, gpio):
"""function called by RPI.GPIO on an bank B interrupt condition.
This function will figure out which MCP230xx pin caused the
interrupt and initiate the appropriate callback function"""
# read INTF register
if self.bank == '16bit':
reg = 0x0F
else: # self.bank = '8bit'
reg = 0x17
regValue = self.single_access_read(reg)
pin = -1
for i in range(0,8):
if regValue == (1<<i):
pin = i + 8
break
value = self.input_at_interrupt(pin)
if self.callBackFuncts[pin][value] != 'empty':
self.callBackFuncts[pin][value](pin)
return
def callbackBoth(self, gpio):
"""function called by RPI.GPIO on either a bank A or bank B
interrupt condition. This function will figure out which MCP230xx
pin caused the interrupt and initiate the appropriate callback function"""
# read INTF register
if self.bank == '16bit':
regA = 0x0E
regB = 0x0F
else: # self.bank = '8bit'
regA = 0x07
regB = 0x17
regValue = self.single_access_read(regA)
pin = -1
# check GPIOA bank for interrupt
for i in range(0,8):
if regValue == (1<<i):
pin = i
break
# check GPIOB bank for interrupt if none found in GPIOA bank
if pin == -1:
regValue = self.single_access_read(regB)
for i in range(0,8):
if regValue == (1<<i):
pin = i + 8
break
value = self.input_at_interrupt(pin)
if self.callBackFuncts[pin][value] != 'empty':
self.callBackFuncts[pin][value](pin)
return
def register_reset(self):
"""register_reset, function to put chip back to default
settings"""
#print('resetting')
if self.chip == 'MCP23008':
self.single_access_write(0x00, 0xFF)
for i in range(1, 12):
self.single_access_write(i, 0x00)
else:
self.set_register_addressing('16bit')
self.single_access_write(0x00, 0xFF)
self.single_access_write(0x01, 0xFF)
for i in range(2, 22):
self.single_access_write(i, 0x00)
return
def __del__(self):
"""__del__, function to clean up expander object and put chip
back to default settings"""
#print('deleting')
self.register_reset()
return
if __name__ == "__main__":
import RPi.GPIO as IO
import time, sys
address = 0x21
intPin = 5
# set up GPIO settings
IO.setwarnings(False)
IO.setmode(IO.BCM)
IO.setup(intPin,IO.IN, pull_up_down=IO.PUD_DOWN) # set intPin to input
MCP = MCP230XX('MCP23017', address, '16bit')
for i in range(0,22):
print(hex(MCP.single_access_read(i)))
def functA(pin):
print('pin '+str(pin)+' interrupted...how rude')
MCP.output(0, 1)
return
def functB(pin):
print('pin '+str(pin)+' is going to sleep')
MCP.output(0, 0)
return
# output tests
MCP.set_mode(0, 'output')
MCP.output(0, 1)
time.sleep(3)
MCP.output(0, 0)
# input tests
MCP.set_mode(2, 'input', 'enable') # was pin 2
#MCP.invert_input(2, True)
for i in range(0,10):
print(MCP.input(2))
time.sleep(0.5)
#MCP.invert_input(2, False)
# interrupt option tests
MCP.interrupt_options(outputType = 'activehigh', bankControl = 'separate')
MCP.set_mode(10,'input', 'enable')
MCP.add_interrupt(10, callbackFunctLow=functA, callbackFunctHigh=functB)
time.sleep(0.5)
IO.add_event_detect(intPin,IO.RISING,callback=MCP.callbackB)
try:
while True:
time.sleep(0.25)
except:
IO.cleanup()
MCP.remove_interrupt(10)
finally:
MCP.__del__()
