Need help with reading from i2c bus

Martin L. OP #7752291
Lesenswert?
• ▲
▼

Andreas B. schrieb:

https://letmegooglethat.com/?q=python+i2c

General you should learn the programming language before what you want to use. This forum is not a programming service.

This is my try but the result this wrong

1
 
#!/usr/bin/python3

2
 
import smbus

3
 
import requests

4
 
import time

5
 


6
 
bus = smbus.SMBus(1)

7
 
address = 0x0F

8
 
x = bus.read_i2c_block_data(address, 0xD0,3)

9
 
voltagein = x[2] <<8 | (x[1])

10
 
#print (x[1])

11
 
#print (x[2])

12
 


13
 
voltagein_string = "%i" % voltagein

14
 
print  (voltagein_string)

15
 
bus.close()

16
 
del x

17
 
del bus
Antwort Zitieren Bearbeiten Löschen Beitrag melden
Martin L. OP #7752326
Lesenswert?
• ▲
▼

Matthias S. schrieb:

Martin L. schrieb:

voltagein = x[2] <<8 | (x[1])

Try:

1
 
> voltagein  = (x[0] * 256) + x[1]

2
 
>

This prints 2 times the same value

1
 
bus = smbus.SMBus(1)

2
 
address = 0x0F

3
 
x = bus.read_i2c_block_data(address, 0xD0,2)

4
 
print ("x")

5
 
print (x)

6
 
#voltagein = (x[1]<<8) | (x[0])

7
 
voltagein  = (x[0] * 256) + x[1]

8
 
voltagein_string = "%i" % voltagein

9
 
print ("voltage in")

10
 
print (voltagein)

11
 
bus.close()

12
 
del x

13
 
del bus

14
 


15
 
time.sleep(2)

16
 
bus = smbus.SMBus(1)

17
 
address = 0x0F

18
 
x = bus.read_i2c_block_data(address, 0xD1,2)

19
 
print ("x")

20
 
print (x)

21
 
#powerextern = x[0] | (x[1]<<8)

22
 
powerextern = (x[0] * 256) + x[1]

23
 
pwerextern_string = "%i" % powerextern

24
 
print ("powerstring")

25
 
print (pwerextern_string)

26
 
bus.close()

27
 
del x

28
 
del bus

1
 
x

2
 
[208, 137]

3
 
voltage in

4
 
53385

5
 
x

6
 
[209, 132]

7
 
powerstring

8
 
53636
Antwort Zitieren Bearbeiten Löschen Beitrag melden
Beitrag #7752374 wurde von einem Moderator gelöscht.
Martin L. OP #7752397
Lesenswert?
• ▲
▼

Martin L. schrieb:

Hmmm schrieb:

Martin L. schrieb:

x [208, 137]

Martin L. schrieb:

x [209, 132]

Seems like the first byte is always the command. What does your debug output look like after reading 3 bytes?

1
 
> [sudo] password for openhabian:

2
 
> x

3
 
> [208, 126, 20]

4
 
> voltage in

5
 
> 53374

6
 
> x

7
 
> [209, 159, 20]

8
 
> powerstring

9
 
> 53663

10
 
> 

11
 
>

1
 
bus = smbus.SMBus(1)

2
 
address = 0x0F

3
 
x = bus.read_i2c_block_data(address, 0xD0,9)

4
 
print ("x")

5
 
print (x)

6
 
voltagein = (x[2]<<8) | (x[1])

7
 
#voltagein  = (x[1] * 256) + x[2]

8
 
voltagein_string = "%i" % voltagein

9
 
print ("voltage in")

10
 
print (voltagein)

11
 
bus.close()

12
 
del x

13
 
del bus

14
 


15
 
time.sleep(2)

16
 
bus = smbus.SMBus(1)

17
 
address = 0x0F

18
 
x = bus.read_i2c_block_data(address, 0xD1,9)

19
 
print ("x")

20
 
print (x)

21
 
powerextern = (x[3]<<8) | x[2]

22
 
#powerextern = (x[0] * 256) + x[1]

23
 
pwerextern_string = "%i" % powerextern

24
 
print ("powerstring")

25
 
print (pwerextern_string)

26
 
bus.close()

27
 
del x

28
 
del bus

1
 
x

2
 
[208, 110, 20, 1, 105, 20, 0, 0, 0]

3
 
voltage in

4
 
5230

5
 
x

6
 
[209, 143, 20, 1, 105, 20, 0, 0, 0]

7
 
powerstring

8
 
276
Antwort Zitieren Bearbeiten Löschen Beitrag melden
Martin L. OP #7752398
Lesenswert?
• ▲
▼

Hmmm schrieb:

Martin L. schrieb:

[208, 126, 20]

powerextern = (x[2] * 256) + x[1]

Das sollte rauskommen

1
 
********************************

2
 
*                              *

3
 
* S.USV solutions              *

4
 
* www.s-usv.com                *

5
 
*                              *

6
 
* Model: Advanced              *

7
 
* Firmware Version: 2.61       *

8
 
* Software Version: 2.40       *

9
 
* Hardware Version: 2.2        *

10
 
*                              *

11
 
* Mail notification: Disabled  *

12
 
*                              *

13
 
* Timed Boot: Disabled         *

14
 
* Boot time: 00:00:00          *

15
 
*                              *

16
 
* Timed Shutdown: Disabled     *

17
 
* Shutdown time: 00:00:00      *

18
 
*                              *

19
 
* Fri Oct 11 18:18:54 2024     *

20
 
*                              *

21
 
********************************

22
 
*                              *

23
 
* Powering Source: Primary     *

24
 
* Charging circuit: OFFLINE    *

25
 
* Charging current: 300 mA     *

26
 
*                              *

27
 
* Voltage in: 5.23 V           *

28
 
* Battery capacity: 100.00%    *

29
 
* Battery voltage: 4.20V       *

30
 
* Power Battery: 000.00 mA     *

31
 
* Power Extern: 1259.00 mA      *

32
 
*                              *

33
 
* Shutdown timer: -1           *

34
 
* Autostart:  enabled          *

35
 
* Sleep timer: 1               *

36
 
*                              *

37
 
********************************
Antwort Zitieren Bearbeiten Löschen Beitrag melden
Martin L. OP #7752408
Lesenswert?
• ▲
▼

Hmmm schrieb:

Martin L. schrieb:

voltage in 5230

5230 mV = 5.230 V

The device seems to send the command byte followed by the low byte and the high byte of the value, so just use (x[2] * 256) + x[1] in both cases.

there is no difference between the commands

1
 
bus = smbus.SMBus(1)

2
 
address = 0x0F

3
 
x = bus.read_i2c_block_data(address, 0xD0,3)

4
 
print ("x")

5
 
print (x)x

6
 
[208, 132, 20]

7
 
voltage in

8
 
5252

9
 
x

10
 
[209, 126, 20]

11
 
powerstring

12
 
5246

13
 


14
 
voltagein = (x[2]<<8) | (x[1])

15
 
#voltagein  = (x[1] * 256) + x[2]

16
 
voltagein_string = "%i" % voltagein

17
 
print ("voltage in")

18
 
print (voltagein)

19
 
bus.close()

20
 
del x

21
 
del bus

22
 


23
 
time.sleep(2)

24
 
bus = smbus.SMBus(1)

25
 
address = 0x0F

26
 
x = bus.read_i2c_block_data(address, 0xD1,3)

27
 
print ("x")

28
 
print (x)

29
 
#powerextern = (x[3]<<8) | x[2]

30
 
powerextern = (x[2] * 256) + x[1]

31
 
#powerextern = (x[0] * 256) + x[1]

32
 
pwerextern_string = "%i" % powerextern

33
 
print ("powerstring")

34
 
print (pwerextern_string)

35
 
bus.close()

36
 
del x

37
 
del bus

1
 
x

2
 
[208, 132, 20]

3
 
voltage in

4
 
5252

5
 
x

6
 
[209, 126, 20]

7
 
powerstring

8
 
5246
Antwort Zitieren Bearbeiten Löschen Beitrag melden
Thread beobachten

Antwort schreiben

Bitte melde dich an, um einen Beitrag zu schreiben.

Bestehender Account

oder

Mit Google-Account einloggen

Noch kein Account?

Die Registrierung ist kostenlos und dauert nur eine Minute.

Jetzt registrieren