Page 9 of 15
Note: If you have problems running any of these programs check the pullup resistors first and the USB power second.
The hardware I2C often works when the software I2C fails because of pullup or USB power problems.
Page 201
from machine import Pin,I2C
i2c0 = I2C(0,scl=Pin(13),sda=Pin(12),freq=100000)
buf = bytearray([0xE7])
i2c0.writeto( 0x40, buf, True)
read= i2c0.readfrom(0x40, 1, True)
print("User Register =",read)
Page 203
from machine import Pin,I2C
i2c0 = I2C(0,scl=Pin(13),sda=Pin(12),freq=100000)
buf = bytearray([0xE3])
i2c0.writeto( 0x40, buf, True)
read = i2c0.readfrom(0x40, 3, True)
msb = read[0]
lsb = read[1]
check = read[2]
print("msb lsb checksum =", msb, lsb, check)
Page 203
from machine import Pin,SoftI2C
i2c0 = SoftI2C(scl=Pin(13),sda=Pin(12),freq=100000)
buf = bytearray([0xE3])
i2c0.writeto( 0x40, buf, False)
read= i2c0.readfrom(0x40, 3, True)
msb = read[0]
lsb = read[1]
check = read[2]
print("msb lsb checksum =", msb, lsb, check)
Page 205
from machine import Pin,I2C
i2c0=I2C(0,scl=Pin(13),sda=Pin(12),freq=100000)
buf = bytearray([0xF3])
i2c0.writeto( 0x40, buf, True)
while True:
try:
read= i2c0.readfrom(0x40, 3, False)
break
except:
continue
msb = read[0]
lsb = read[1]
check = read[2]
print("msb lsb checksum =", msb, lsb, check)
Page 205
from machine import Pin,SoftI2C
from time import sleep_ms
i2c0 = SoftI2C(scl=Pin(18),sda=Pin(19),freq=100000)
buf = bytearray([0xF3])
i2c0.writeto( 0x40, buf, False)
while True:
sleep_ms(5)
try:
read = i2c0.readfrom(0x40, 3, True)
break
except:
continue
msb = read[0]
lsb = read[1]
check = read[2]
print("msb lsb checksum =", msb, lsb, check)
Page 206
from machine import Pin,I2C
def crcCheck(msb, lsb,check):
data32 = (msb << 16)|(lsb <<8)| check
divisor = 0x988000
for i in range(16):
if data32 & 1<<(23 - i):
data32 ^= divisor
divisor>>= 1
return data32
i2c0=I2C(0,scl=Pin(13),sda=Pin(12),freq=100000)
buf = bytearray([0xF3])
i2c0.writeto( 0x40, buf, False)
while True:
try:
read= i2c0.readfrom(0x40, 3, True)
break
except:
continue
msb = read[0]
lsb = read[1]
check = read[2]
print("msb lsb checksum =", msb, lsb, check)
data16= (msb << 8) | (lsb & 0xFC)
temp = (-46.85 +(175.72 * data16 /(1<<16)))
print("Temperature C ", temp)
print("Checksum=",crcCheck(msb,lsb,check))
buf = bytearray([0xF5])
i2c0.writeto( 0x40, buf, True)
read=bytearray(3)
while True:
try:
i2c0.readfrom_into(0x40,read, True)
break
except:
continue
msb = read[0]
lsb = read[1]
check = read[2]
print("msb lsb checksum =", msb, lsb, check)
data16 = (msb << 8) | (lsb & 0xFC)
hum = -6 + (125.0 * data16) / 65536
print("Humidity ", hum)
print("Checksum=",crcCheck(msb,lsb,check))
