Hi.
Usually that error means a bad I2C connection or that it can’t find the I2C device.
Can you share a bit of your code?
Regards,
Sara

Hello Sara,
Thanks for coming back to me.
The code I am running is as follows;
import machine, utime, math, tm1637,urtc, neopixel
from machine import I2C, Pin
from lcd_api import LcdApi
from i2c_lcd import I2cLcd
day_of_week = [ ‘ ‘, ‘Tue’, ‘Wed’, ‘Thu’, ‘Fri’, ‘Sat’, ‘Sun’, ‘Mon’]
month = [‘ ‘, ‘Jan’, ‘Feb’, ‘Mar’, ‘Apr’, ‘May’, ‘Jun’,’Jul’, ‘Aug’, ‘Sep’, ‘Oct’, ‘Nov’, ‘Dec’]
# Initialize RTC (connected to I2C)
i2c = I2C(1, scl=Pin(7), sda=Pin(6))
rtc = urtc.DS3231(i2c)
I2C1_ADDR = 39
I2C1_NUM_ROWS = 2
I2C1_NUM_COLS = 16
I2C2_ADDR = 39
I2C2_NUM_ROWS = 2
I2C2_NUM_COLS = 16
i2c1 = I2C(0, sda=machine.Pin(0), scl=machine.Pin(1), freq = 400000)
lcd1 = I2cLcd(i2c1, I2C1_ADDR, I2C1_NUM_ROWS, I2C1_NUM_COLS)
i2c2 = I2C(1, sda=machine.Pin(2), scl=machine.Pin(3), freq = 400000)
lcd2 = I2cLcd(i2c2, I2C2_ADDR, I2C2_NUM_ROWS, I2C2_NUM_COLS)
display = tm1637.TM1637(clk=Pin(5), dio=Pin(4))
pixel_pin = 16
pixel = neopixel.NeoPixel(machine.Pin(pixel_pin), 1)
mode_button = machine.Pin(11, machine.Pin.IN, machine.Pin.PULL_DOWN)
select_button = machine.Pin(10, machine.Pin.IN, machine.Pin.PULL_DOWN)
up_button = machine.Pin(9, machine.Pin.IN, machine.Pin.PULL_DOWN)
down_button = machine.Pin(8, machine.Pin.IN, machine.Pin.PULL_DOWN)
thermo1 = machine.ADC(26)
thermo2 = machine.ADC(27)
led = machine.Pin(13, machine.Pin.OUT)
buzzer = machine.Pin(12, machine.Pin.OUT)
conversion_factor1 = 3.845 / 65535
conversion_factor2 = 3.845 / 65535
def tempIN(reading1):
Rt1 = 10 * reading1 / (3.3 – reading1) # calculate the resistance value
tempK1 = 1/(1/(273.15 + 25) + math.log(Rt1/10)/3950.0) # calculate temperature in Kelvins
return (int((tempK1 – 273.15)*10))/10
def tempOUT(reading2):
Rt2 = 10 * reading2 / (3.3 – reading2)
tempK2 = 1/(1/(273.15 + 25) + math.log(Rt2/10)/3950.0)
return (int((tempK2 – 273.15)*10))/10
def time_display():
timed = “%02d%02d%02d”%(timestamp[4:7])
HRdi = timed[0:2]
HRd = int(HRdi) + 1
if HRd == 24:
HRd = 0
MNdi = timed[2:4]
MNd = int(MNdi)
display.brightness(1)
display.numbers(HRd, MNd)
def display_alarm():
timestamp = rtc.datetime()
display.brightness(0)
if a_M > timestamp.month or (a_M == timestamp.month and a_date_int > timestamp.day):
a_Md = str(a_M)
if len(a_Md) == 1:
a_Md = “0” + a_Md
display.show(a_date + a_Md)
if a_M == timestamp.month and a_date_int == timestamp.day:
display.numbers(a_hour_int, a_min_int)
if a_M < timestamp.month or (a_M == timestamp.month and a_date_int < timestamp.day) or (a_M == timestamp.month and a_date_int == timestamp.day and a_hour_int < (timestamp.hour + 1) or (a_M == timestamp.month and a_date_int == timestamp.day and a_hour_int == (timestamp.hour + 1) and a_min_int < timestamp.minute) or (a_M == timestamp.month and a_date_int == timestamp.day and a_hour_int == (timestamp.hour + 1) and a_min_int == timestamp.minute and timestamp.second > 0)):
display.show(” “)
def alarm_handler(pin):
global mode, a_date, a_date_int, a_M, a_hour_int, a_min_int

mode = 0

timestamp = rtc.datetime()
time_display()
utime.sleep(1.5)
display.show(” “)

if mode_button.value() == 1:
mode = 1

if mode == 1:
a_date_int = timestamp.day
a_date = str(a_date_int)
if len(a_date) == 1:
a_date = “0” + a_date
a_M = timestamp.month
a_month = month[a_M]
a_hour_int = timestamp.hour + 1
a_hour = str(a_hour_int)
if len(a_hour) == 1:
a_hour = “0” + a_hour
a_min_int = timestamp.minute
a_min = str(a_min_int)
if len(a_min) == 1:
a_min = “0” + a_min
lcd1.clear()
lcd1.move_to(3,0)
lcd1.putstr(“Set Alarm”)
lcd1.move_to(0,1)
lcd1.putstr(“Date: ” + str(a_date))
led.value(1)
buzzer.value(1)
utime.sleep(0.1)
led.value(0)
buzzer.value(0)

while mode == 1:

if up_button.value() == 1:
a_date_int += 1
utime.sleep(0.5)
if a_date_int == 32:
a_date_int = 1
if down_button.value() == 1:
a_date_int -= 1
if a_date_int == 0:
a_date_int = 31
utime.sleep(0.5)
a_date = str(a_date_int)
if len(a_date) == 1:
a_date = “0” + a_date
lcd1.move_to(6,1)
lcd1.putstr(a_date)

if select_button.value() == 1:
mode = 2
lcd1.move_to(0,1)
lcd1.putstr(” “)
lcd1.move_to(0,1)
lcd1.putstr(“Month: ” + a_month)
utime.sleep(0.5)

while mode == 2:
if mode_button.value == 1:
mode = 0
utime.sleep(0.5)
if up_button.value() == 1:
a_M += 1
if a_M == 13:
a_M = 1
utime.sleep(0.5)
if down_button.value() == 1:
a_M -= 1
if a_M == 0:
a_M = 12
utime.sleep(0.5)
a_month = month[a_M]
lcd1.move_to(7,1)
lcd1.putstr(a_month)
if select_button.value() == 1:
mode = 3
lcd1.move_to(0,1)
lcd1.putstr(” “)
lcd1.move_to(0,1)
lcd1.putstr(“Hour: ” + a_hour)
utime.sleep(0.5)

while mode == 3:
if mode_button.value() == 1:
mode = 0
utime.sleep(0.5)
if up_button.value() == 1:
a_hour_int += 1
if a_hour_int == 24:
a_hour_int = 0
utime.sleep(0.5)
if down_button.value() == 1:
a_hour_int -= 1
if a_hour_int == -1:
a_hour_int = 23
utime.sleep(0.5)
a_hour = str(a_hour_int)
if len(a_hour) == 1:
a_hour = “0” + a_hour
lcd1.move_to(6,1)
lcd1.putstr(a_hour)

if select_button.value() == 1:
mode = 4
lcd1.move_to(0,1)
lcd1.putstr(” “)
lcd1.move_to(0,1)
lcd1.putstr(“Minutes: ” + a_min)
utime.sleep(0.5)

while mode == 4:
if mode_button.value() == 1:
mode = 0
utime.sleep(0.5)
if up_button.value() == 1:
a_min_int += 1
if a_min_int == 60:
a_min_int = 0
utime.sleep(0.5)
if down_button.value() == 1:
a_min_int -= 1
if a_min_int == -1:
a_min_int = 59
utime.sleep(0.5)
a_min = str(a_min_int)
if len(a_min) == 1:
a_min = “0” + a_min
lcd1.move_to(9,1)
lcd1.putstr(str(a_min))
if select_button.value() == 1:
utime.sleep(0.5)
lcd1.clear()
lcd1.move_to(1,0)
lcd1.putstr(“Alarm set for”)
lcd1.move_to(1,1)
lcd1.putstr(a_date + ” ” + a_month + ” / ” + a_hour + “:” + a_min)
utime.sleep(2)

timestamp = rtc.datetime()
DAY = day_of_week[timestamp.weekday]
D = timestamp.day
D1 = D
S1 = timestamp.second
MT = month[timestamp.month]
M = timestamp.month
H = int(timestamp[4]) + 1
H1 = H
Min1 = timestamp.minute
HR = str(H)
if len(HR) == 1:
HR = “0” + HR
time = HR + “:” + “%02d:%02d”%(timestamp[5:7])
date = DAY + ” %02d “%(timestamp[2:3]) + MT + ” %04d”%(timestamp[0:1])
lcd1.clear()
lcd1.move_to(0,0)
lcd1.putstr(date)
lcd1.move_to(4,1)
lcd1.putstr(time)
display_alarm()
mode = 0

mode_button.irq(trigger = machine.Pin.IRQ_RISING, handler = alarm_handler)

flag1 = 0
flag2 = 0
a_date_int = 1
a_M = 6
a_hour_int = 12
a_min_int = 0
timestamp = rtc.datetime()
time_display()
DAY = day_of_week[timestamp.weekday]
D = timestamp.day
D1 = D
S1 = timestamp.second
MT = month[timestamp.month]
M = timestamp.month
H = int(timestamp[4]) + 1
H1 = H
Min1 = timestamp.minute
HR = str(H)
if len(HR) == 1:
HR = “0” + HR
time = HR + “:” + “%02d:%02d”%(timestamp[5:7])
date = DAY + ” %02d “%(timestamp[2:3]) + MT + ” %04d”%(timestamp[0:1])
display.show(” “)
sentence = ” Livingroom project commissioned on Wednesday 1st May 2024 “
w = len(sentence)- 14
lcd1.clear()
for i in range(w):
lcd1.move_to(0,0)
lcd1.putstr(sentence[(i-1):(i+15)])
utime.sleep(0.25)
lcd1.clear()
lcd1.move_to(0,0)
lcd1.putstr(date)
lcd1.move_to(4,1)
lcd1.putstr(time)
reading1 = thermo1.read_u16() * conversion_factor1
reading2 = thermo2.read_u16() * conversion_factor2
tempC1 = tempIN(reading1)
if tempC1 > 99.9:
tempC1 = int(tempC1)
tempC2 = tempOUT(reading2)
if tempC2 > 99.9:
tempC2 = int(tempC2)
lcd2.clear()
lcd2.move_to(0,0)
lcd2.putstr(“Temp IN:”)
lcd2.move_to(10,0)
lcd2.putstr(str(tempC1))
lcd2.move_to(15,0)
lcd2.putstr(“C”)
lcd2.move_to(0,1)
lcd2.putstr(“Temp OUT:”)
lcd2.move_to(10,1)
lcd2.putstr(str(tempC2))
lcd2.move_to(15,1)
lcd2.putstr(“C”)
p = 0
count = 0
while True:
if p == 0:
pixel[0] = (10, 0, 0)
elif p == 1:
pixel[0] = (0, 10, 0)
else:
pixel[0] = (0, 0, 10)
pixel.write()

timestamp = rtc.datetime()

if a_date_int == timestamp.day and a_M == timestamp.month and a_hour_int == (timestamp.hour + 1) and a_min_int == timestamp.minute and timestamp.second == 0:
display.brightness(1)
hrd = timestamp.hour + 1
mnd = timestamp.minute
display.numbers(hrd,mnd)
for j in range (3):
for i in range (5):
buzzer.value(1)
utime.sleep(0.2)
buzzer.value (0)
utime.sleep(0.5)
display.show(” “)

reading1 = thermo1.read_u16() * conversion_factor1
reading2 = thermo2.read_u16() * conversion_factor2
tempC1 = tempIN(reading1)
if tempC1 > 99.9:
tempC1 = int(tempC1)
tempC2 = tempOUT(reading2)
if tempC2 > 99.9:
tempC2 = int(tempC2)

if tempC1 >= 75 or tempC2 >= 75:
led.value(1)
buzzer.value(1)
lcd2.move_to(10,0)
lcd2.putstr(str(tempC1))
lcd2.move_to(10,1)
lcd2.putstr(str(tempC2))
utime.sleep(0.25)
led.value(0)
utime.sleep(0.25)
else:
led.value(0)
buzzer.value(0)

count += 1

if count == 2000:
lcd2.move_to(10,0)
lcd2.putstr(str(tempC1))
lcd2.move_to(10,1)
lcd2.putstr(str(tempC2))
count = 0

DAY = day_of_week[timestamp.weekday]
D = timestamp.day
D1 = D
MT = month[timestamp.month]
M = timestamp.month
H = int(timestamp[4]) + 1
HR = str(H)
if len(HR) == 1:
HR = “0” + HR
time = HR + “:” + “%02d:%02d”%(timestamp[5:7])
date = DAY + ” %02d “%(timestamp[2:3]) + MT + ” %04d”%(timestamp[0:1])
if H == 24:
HR = “00”
D+=1
DW = timestamp.weekday + 1
DATE = str(D)
if len(DATE) == 1:
DATE = “0” + DATE
if DW == 8:
DW = 1
DAY = day_of_week[DW]
YEAR = “%04d”%(timestamp[0:1])
if (M == 1 or M == 3 or M == 5 or M == 7 or M == 8 or M == 10) and D == 32:
DATE = “01”
M = M + 1
flag1 = 1
if (M == 4 or M == 6 or M == 9 or M == 11) and D == 31:
DATE = “01”
M = M + 1
if M == 1 and flag1 == 0 and (int(timestamp.year/4) == timestamp.year/4) and D == 30:
DATE = “01”
M = 2
if M == 1 and flag1 == 0 and (int(timestamp.year/4) != timestamp.year/4) and D == 29:
DATE = “01”
M = 2
if M == 12 and D == 32:
DATE = “01”
M = 1
YEAR = str(timestamp.year + 1)
MT = month[M]

time = HR + “:” + “%02d:%02d”%(timestamp[5:7])
date = DAY + ” ” + DATE + ” ” + MT + ” ” + YEAR

# Daylight saving time correction
if D > 24 and D < 32 and M == 3 and DW == 0 and timestamp.second == 0 and timestamp.minute == 0 and H == 2:
H += 1
HR = “0” + str(H)
flag2 = 0
time = HR + “:” + “%02d:%02d”%(timestamp[5:7])
if D > 24 and D < 32 and M == 10 and DW == 0 and timestamp.second == 0 and timestamp.minute == 0 and H == 3 and flag2 == 0:
H -= 1
HR = “0” + str(H)
flag2 = 1
time = HR + “:” + “%02d:%02d”%(timestamp[5:7])

if D1 != D:
lcd1.move_to(0,0)
lcd1.putstr(date)
D1 = D
if H1 != H:
lcd1.move_to(4,1)
lcd1.putstr(HR)
H1 = H
if Min1 != timestamp.minute:
lcd1.move_to(7,1)
lcd1.putstr(“%02d”%(timestamp.minute))
Min1 = timestamp.minute
display_alarm()
if S1 != timestamp.second:
lcd1.move_to(10,1)
lcd1.putstr(“%02d”%(timestamp.second))
S1 = timestamp.second

p+=1
if p == 3:
p = 0

# Display time every quarter hour
if (Min1 == 0 or Min1 == 15 or Min1 == 30 or Min1 == 45) and S1 == 0:
buzzer.value(1)
utime.sleep(0.1)
buzzer.value(0)
time_display()
utime.sleep(1.5)
display.show(” “)
I have some doubts whether it is actually a faulty electrical connection. 
When I power on the RP 2040 and run a program to synchronize the DS3231, the program runs fine. Then when I try to run the above program I get the following error message:
Traceback (most recent call last):
File “<stdin>”, line 25, in <module>
File “i2c_lcd.py”, line 22, in __init__
OSError: [Errno 5] EIO
If I run a program to detect the address of LCD2 to check whether I have a poor connection with the LCD2 display, I get an answer.
Then I if I again try to run the program to synchronize the DS3231 (to check the connections to this peripheral) I get the following error report:
Traceback (most recent call last):
File “<stdin>”, line 26, in <module>
File “urtc.py”, line 134, in datetime
File “urtc.py”, line 45, in _register
OSError: [Errno 5] EIO
In order to be able to make this RTC synching program run again I have to power off the RP2040 by removing the USB lead and reconnect it.
To me it seems that the program is causing the clock of the DS3231 to crash.
That’s my poor evaluation of the problem.
 
Regards,
Philip

Hi.
I’m sorry for taking so long to get back to you.
Usually that error is related to incorrect wiring or pin definition.
Can you please share the code using pstebin or github? Otherwise identation gets all messed up.
 
Regards,
Sara

Hello Sara,
Thanks for your suggestion. I am an absolute beginner and your suggestions help me a lot in probing my war around.
I have uploaded the code in GitHub. The link to the code is https://github.com/Philip-1962/Hobby-projects/blob/main/Clock%20and%20alarm
I hope I got this right!
 
Regards,
 
 

Hi.
I think the problem is related to the way you’re creating your I2C channels.
 
For the RTC you’re creating an I2C bus on channel 1 and GPIOs 7 and 6.

i2c = I2C(1, scl=Pin(7), sda=Pin(6))

For LCD2, you’re creating a different bus on the same channel but different GPIOs?

i2c2 = I2C(1, sda=machine.Pin(2), scl=machine.Pin(3), freq = 400000)

I think you don’t need this extra i2c instance because you’ll be using multiple devices with different addresses, the RTC and the LCD.
 
So, after initializing the i2c instance for the RTC, you can use that same one for the LCD2 and connect it to the same I2C pins.

lcd2 = I2cLcd(i2c, I2C2_ADDR, I2C2_NUM_ROWS, I2C2_NUM_COLS)

 
I hope this is clear.
Regards,
Sara

Dear Sara,
Thank you very much for your prompt reply, and on a Sunday!
You nailed it!
That was the problem. I did as instructed and it worked perfectly.
Thank you for teaching me something new.
 
Best regards,
Philip

Great.
I’m glad it worked.
I’ll mark this issue as resolved. If you need further help, you just need to open a new question in our forum.
Regards,
Sara