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mcp23017_lib.py
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mcp23017_lib.py
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#!/usr/bin/python
# Filename: mcp23017_lib.py
"""This module provides an easy interface for the MCP23017"""
__license__ = "GPLv3"
import smbus
i2c = smbus.SMBus(1)
OUT = 0
IN = 1
BANK_A = 0
BANK_B = 1
ALL = 2
LAT_A = 3
LAT_B = 4
PU_A = 5
PU_B = 6
HIGH = 1
LOW = 0
PUHIGH = 1
PULOW = 0
ADDRESS = 0x20
def puRead(bank=None):
"""
Reads and returns the pullup registers from both GPIO banks
Param 'bank': select which bank/s should be returned. Use PU_A, PU_B, ALL or leave blank
for a default graphic diagram.
Return: returns the selected bank/s. If blank, a graphic diagram will be returned instead.
"""
if(bank == PU_A):
print PUA
elif(bank == PU_B):
print PUB
elif(bank == ALL):
print PUA, PUB
else:
print " --------"
print PUB[7] + "|8 9|" + PUA[0]
print PUB[6] + "|7 10|" + PUA[1]
print PUB[5] + "|6 11|" + PUA[2]
print PUB[4] + "|5 12|" + PUA[3]
print PUB[3] + "|4 13|" + PUA[4]
print PUB[2] + "|3 14|" + PUA[5]
print PUB[1] + "|2 15|" + PUA[6]
print PUB[0] + "|1 16|" + PUA[7]
print " --------"
def dirRead(bank=None):
"""
Reads and returns the direction registers from both GPIO banks
Param 'bank': select which bank/s should be returned. Use BANK_A, BANK_B, ALL or leave blank
for a default graphic diagram.
Return: returns the selected bank/s. If blank, a graphic diagram will be returned instead.
"""
if(bank == BANK_A):
print DIRA
elif(bank == BANK_B):
print DIRB
elif(bank == ALL):
print DIRA, DIRB
else:
print " --------"
print DIRB[7] + "|8 9|" + DIRA[0]
print DIRB[6] + "|7 10|" + DIRA[1]
print DIRB[5] + "|6 11|" + DIRA[2]
print DIRB[4] + "|5 12|" + DIRA[3]
print DIRB[3] + "|4 13|" + DIRA[4]
print DIRB[2] + "|3 14|" + DIRA[5]
print DIRB[1] + "|2 15|" + DIRA[6]
print DIRB[0] + "|1 16|" + DIRA[7]
print " --------"
def latRead(bank=None):
"""
Reads and returns the latch registers from both GPIO banks
Param 'bank': select which latch/es should be returned. Use LAT_A, LAT_B, ALL or leave blank
for a default graphic diagram.
Return: returns the selected latch/es. If blank, a graphic diagram will be returned instead.
"""
if(bank == LAT_A):
print LATA
elif(bank == LAT_B):
print LATB
elif(bank == ALL):
print LATA, LATB
else:
print " --------"
print LATB[7] + "|8 9|" + LATA[0]
print LATB[6] + "|7 10|" + LATA[1]
print LATB[5] + "|6 11|" + LATA[2]
print LATB[4] + "|5 12|" + LATA[3]
print LATB[3] + "|4 13|" + LATA[4]
print LATB[2] + "|3 14|" + LATA[5]
print LATB[1] + "|2 15|" + LATA[6]
print LATB[0] + "|1 16|" + LATA[7]
print " --------"
def start(address):
"""
Starts, initializes and reads the chip specified with the address parameter.
Param 'address': a valid chip address, in hexadecimal format.
Return: ValueError if address is invalid
"""
global ADDRESS, DIRA, DIRB, LATA, LATB, PUA, PUB
try:
int(str(address), 16)
except:
raise ValueError(str(address) + " is not a valid chip address")
ADDRESS = address
DIRA = str(bin(i2c.read_byte_data(ADDRESS, 0x00))).replace("0b", "").rjust(8, '0')
DIRB = str(bin(i2c.read_byte_data(ADDRESS, 0x01))).replace("0b", "").rjust(8, '0')
LATA = str(bin(i2c.read_byte_data(ADDRESS, 0x14))).replace("0b", "").rjust(8, '0')
LATB = str(bin(i2c.read_byte_data(ADDRESS, 0x15))).replace("0b", "").rjust(8, '0')
PUA = str(bin(i2c.read_byte_data(ADDRESS, 0x0C))).replace("0b", "").rjust(8, '0')
PUB = str(bin(i2c.read_byte_data(ADDRESS, 0x0D))).replace("0b", "").rjust(8, '0')
def setup(pin, mode, pullEnable=None):
"""
Writes direction (IN, OUT) based on pin number. Also enables internall pullup if specified.
Param 'pin': Any pin from 1 to 16.
Param 'mode': Defines pin direction, input (IN) or output (OUT).
Param 'pullEnable' (optional): Enables internal pullup resistor when setting a pin as an input.
Values are PUHIGH and PULOW.
Return: ValueError if pin or mode are invalid.
"""
global DIRA, DIRB, PUA, PUB
if(str(pin).isdigit() and (0 < pin < 17)):
if(mode == OUT or mode == IN):
if(0 < pin < 9):
DIRB = DIRB[0:pin - 1] + str(mode) + DIRB[pin:]
i2c.write_byte_data(ADDRESS, 0x01, int(DIRB, 2))
if((pullEnable == PUHIGH or pullEnable == PULOW) and mode == IN):
PUB = PUB[0:pin - 1] + str(pullEnable) + PUB[pin:]
i2c.write_byte_data(ADDRESS, 0x0D, int(PUB, 2))
elif(8 < pin < 17):
DIRA = DIRA[0:(pin - 8) - 1] + str(mode) + DIRA[(pin - 8):]
i2c.write_byte_data(ADDRESS, 0x00, int(DIRA, 2))
if((pullEnable == PUHIGH or pullEnable == PULOW) and mode == IN):
PUA = PUA[0:(pin - 8) - 1] + str(pullEnable) + PUA[(pin - 8):]
i2c.write_byte_data(ADDRESS, 0x0C, int(PUA, 2))
else:
raise ValueError(str(mode) + " is not a valid mode")
else:
raise ValueError(str(pin) + " is not a valid pin number")
def output(pin, dir):
"""
Writes state (HIGH, LOW) based on pin number.
Param 'pin': Any pin from 1 to 16.
Param 'dir': Defines pin state, on (HIGH) or off (LOW).
Return: ValueError if pin or dir are invalid.
"""
global LATA, LATB
if(str(pin).isdigit() and (0 < pin < 17)):
if(dir == HIGH or dir == LOW):
if(0 < pin < 9):
LATB = LATB[0:pin - 1] + str(dir) + LATB[pin:]
i2c.write_byte_data(ADDRESS, 0x15, int(LATB, 2))
elif(8 < pin < 17):
LATA = LATA[0:(pin - 8) - 1] + str(dir) + LATA[(pin - 8):]
i2c.write_byte_data(ADDRESS, 0x14, int(LATA, 2))
else:
raise ValueError(str(dir) + " is not a valid state")
else:
raise ValueError(str(pin) + " is not a valid number")
def input(pin):
"""
Reads and returns pin state.
Param 'pin': Pin to be read. Any pin from 1 to 16
Return: True if state == 1, False if state == 0
"""
if(str(pin).isdigit() and (0 < pin < 17)):
if(0 < pin < 9):
out = str(bin(i2c.read_byte_data(ADDRESS, 0x13))).replace("0b", "").rjust(8, '0')[pin - 1]
elif(8 < pin < 17):
out = str(bin(i2c.read_byte_data(ADDRESS, 0x12))).replace("0b", "").rjust(8, '0')[pin - 9]
return True if out == "1" else False