I cannot make i2c work in raspberry pi Zero W

[Ramiro Aceves <ea1abz%gmail.com@localhost>]

Hello,

I have connected a BMP280 pressure sensor to my piZeroW just to learn a little of i2c programming on NetBSD. Before doing real programming I issued a i2scan command to ensure the system works, but a lot of inexistent devices are detected (even if nothing is connected to the pi)

netbsd-raspaZeroW# i2cscan /dev/iic0
/dev/iic0: found device at 0x09
/dev/iic0: found device at 0x0a
/dev/iic0: found device at 0x0b
/dev/iic0: found device at 0x0d
/dev/iic0: found device at 0x0e
/dev/iic0: found device at 0x0f
/dev/iic0: found device at 0x10
/dev/iic0: found device at 0x11
/dev/iic0: found device at 0x12
/dev/iic0: found device at 0x13
/dev/iic0: found device at 0x14
/dev/iic0: found device at 0x15
/dev/iic0: found device at 0x16
/dev/iic0: found device at 0x17
/dev/iic0: found device at 0x18
/dev/iic0: found device at 0x19
/dev/iic0: found device at 0x1a
/dev/iic0: found device at 0x1b
/dev/iic0: found device at 0x1c
/dev/iic0: found device at 0x1d
/dev/iic0: found device at 0x1e
/dev/iic0: found device at 0x1f
/dev/iic0: found device at 0x20
/dev/iic0: found device at 0x21
/dev/iic0: found device at 0x22
/dev/iic0: found device at 0x23
/dev/iic0: found device at 0x24
/dev/iic0: found device at 0x25
/dev/iic0: found device at 0x26
/dev/iic0: found device at 0x27
/dev/iic0: found device at 0x29
/dev/iic0: found device at 0x2a
/dev/iic0: found device at 0x2b                   /dev/iic0: found device at 0x2c
/dev/iic0: found device at 0x2d                   /dev/iic0: found device at 0x2e
/dev/iic0: found device at 0x2f                   /dev/iic0: found device at 0x30
/dev/iic0: found device at 0x31
/dev/iic0: found device at 0x32                   /dev/iic0: found device at 0x33
/dev/iic0: found device at 0x34                   /dev/iic0: found device at 0x35
/dev/iic0: found device at 0x36                   /dev/iic0: found device at 0x38
/dev/iic0: found device at 0x39                   /dev/iic0: found device at 0x3a
/dev/iic0: found device at 0x3b
/dev/iic0: found device at 0x3c
/dev/iic0: found device at 0x3d
/dev/iic0: found device at 0x3e
/dev/iic0: found device at 0x3f
/dev/iic0: found device at 0x40
/dev/iic0: found device at 0x41
/dev/iic0: found device at 0x42
/dev/iic0: found device at 0x43
/dev/iic0: found device at 0x44
/dev/iic0: found device at 0x45
/dev/iic0: found device at 0x46
/dev/iic0: found device at 0x47                   /dev/iic0: found device at 0x4c
/dev/iic0: found device at 0x4d                   /dev/iic0: found device at 0x4e
/dev/iic0: found device at 0x4f
/dev/iic0: found device at 0x50                   /dev/iic0: found device at 0x51
/dev/iic0: found device at 0x52                   /dev/iic0: found device at 0x53
/dev/iic0: found device at 0x54
/dev/iic0: found device at 0x55                   /dev/iic0: found device at 0x56
/dev/iic0: found device at 0x57                   /dev/iic0: found device at 0x58
/dev/iic0: found device at 0x59
/dev/iic0: found device at 0x5a                   /dev/iic0: found device at 0x5b
/dev/iic0: found device at 0x5c                   /dev/iic0: found device at 0x5d
/dev/iic0: found device at 0x5e
/dev/iic0: found device at 0x5f                   /dev/iic0: found device at 0x60
/dev/iic0: found device at 0x62                   /dev/iic0: found device at 0x63
/dev/iic0: found device at 0x64
/dev/iic0: found device at 0x65                   /dev/iic0: found device at 0x66
/dev/iic0: found device at 0x67                   /dev/iic0: found device at 0x68
/dev/iic0: found device at 0x69
/dev/iic0: found device at 0x6a
/dev/iic0: found device at 0x6b
/dev/iic0: found device at 0x6c
/dev/iic0: found device at 0x6d                   /dev/iic0: found device at 0x6e
/dev/iic0: found device at 0x6f
/dev/iic0: found device at 0x70
/dev/iic0: found device at 0x71
/dev/iic0: found device at 0x72
/dev/iic0: found device at 0x73
/dev/iic0: found device at 0x74
/dev/iic0: found device at 0x75
/dev/iic0: found device at 0x76
/dev/iic0: found device at 0x77                   /dev/iic0: 103 devices found
netbsd-raspaZeroW# i2cscan /dev/iic1              /dev/iic1: found device at 0x09
/dev/iic1: found device at 0x0a
/dev/iic1: found device at 0x0b                   /dev/iic1: found device at 0x0d
/dev/iic1: found device at 0x0e
/dev/iic1: found device at 0x0f
/dev/iic1: found device at 0x10
/dev/iic1: found device at 0x11
/dev/iic1: found device at 0x12                   /dev/iic1: found device at 0x13
/dev/iic1: found device at 0x14
/dev/iic1: found device at 0x15
/dev/iic1: found device at 0x16
/dev/iic1: found device at 0x17                   /dev/iic1: found device at 0x18
/dev/iic1: found device at 0x19
/dev/iic1: found device at 0x1a
/dev/iic1: found device at 0x1b
/dev/iic1: found device at 0x1c
/dev/iic1: found device at 0x1d
/dev/iic1: found device at 0x1e
/dev/iic1: found device at 0x1f
/dev/iic1: found device at 0x20
/dev/iic1: found device at 0x21                   /dev/iic1: found device at 0x22
/dev/iic1: found device at 0x23                   /dev/iic1: found device at 0x24
/dev/iic1: found device at 0x25
/dev/iic1: found device at 0x26                   /dev/iic1: found device at 0x27
/dev/iic1: found device at 0x29
/dev/iic1: found device at 0x2a
/dev/iic1: found device at 0x2b
/dev/iic1: found device at 0x2c
/dev/iic1: found device at 0x2d                   /dev/iic1: found device at 0x2e
/dev/iic1: found device at 0x2f
/dev/iic1: found device at 0x30                   /dev/iic1: found device at 0x31
/dev/iic1: found device at 0x32                   /dev/iic1: found device at 0x33
/dev/iic1: found device at 0x34                   /dev/iic1: found device at 0x35
/dev/iic1: found device at 0x36                   /dev/iic1: found device at 0x38
/dev/iic1: found device at 0x39
/dev/iic1: found device at 0x3a
/dev/iic1: found device at 0x3b                   /dev/iic1: found device at 0x3c
/dev/iic1: found device at 0x3d
/dev/iic1: found device at 0x3e
/dev/iic1: found device at 0x3f                   /dev/iic1: found device at 0x40
/dev/iic1: found device at 0x41
/dev/iic1: found device at 0x42
/dev/iic1: found device at 0x43
/dev/iic1: found device at 0x44
/dev/iic1: found device at 0x45
/dev/iic1: found device at 0x46
/dev/iic1: found device at 0x47                   /dev/iic1: found device at 0x4c
/dev/iic1: found device at 0x4d
/dev/iic1: found device at 0x4e
/dev/iic1: found device at 0x4f
/dev/iic1: found device at 0x50
/dev/iic1: found device at 0x51
/dev/iic1: found device at 0x52
/dev/iic1: found device at 0x53
/dev/iic1: found device at 0x54
/dev/iic1: found device at 0x55
/dev/iic1: found device at 0x56
/dev/iic1: found device at 0x57
/dev/iic1: found device at 0x58
/dev/iic1: found device at 0x59
/dev/iic1: found device at 0x5a
/dev/iic1: found device at 0x5b
/dev/iic1: found device at 0x5c
/dev/iic1: found device at 0x5d
/dev/iic1: found device at 0x5e
/dev/iic1: found device at 0x5f
/dev/iic1: found device at 0x60
/dev/iic1: found device at 0x62
/dev/iic1: found device at 0x63
/dev/iic1: found device at 0x64
/dev/iic1: found device at 0x65
/dev/iic1: found device at 0x66
/dev/iic1: found device at 0x67
/dev/iic1: found device at 0x68
/dev/iic1: found device at 0x69
/dev/iic1: found device at 0x6a
/dev/iic1: found device at 0x6b
/dev/iic1: found device at 0x6c
/dev/iic1: found device at 0x6d
/dev/iic1: found device at 0x6e
/dev/iic1: found device at 0x6f
/dev/iic1: found device at 0x70
/dev/iic1: found device at 0x71
/dev/iic1: found device at 0x72
/dev/iic1: found device at 0x73
/dev/iic1: found device at 0x74
/dev/iic1: found device at 0x75
/dev/iic1: found device at 0x76
/dev/iic1: found device at 0x77
/dev/iic1: 103 devices found
netbsd-raspaZeroW# i2cscan /dev/iic2
/dev/iic2: found device at 0x09
/dev/iic2: found device at 0x0a
/dev/iic2: found device at 0x0b
/dev/iic2: found device at 0x0d
/dev/iic2: found device at 0x0e
/dev/iic2: found device at 0x0f
/dev/iic2: found device at 0x10
/dev/iic2: found device at 0x11
/dev/iic2: found device at 0x12
/dev/iic2: found device at 0x13
/dev/iic2: found device at 0x14
/dev/iic2: found device at 0x15
/dev/iic2: found device at 0x16
/dev/iic2: found device at 0x17
/dev/iic2: found device at 0x18
/dev/iic2: found device at 0x19
/dev/iic2: found device at 0x1a
/dev/iic2: found device at 0x1b
/dev/iic2: found device at 0x1c
/dev/iic2: found device at 0x1d
/dev/iic2: found device at 0x1e
/dev/iic2: found device at 0x1f
/dev/iic2: found device at 0x20
/dev/iic2: found device at 0x21
/dev/iic2: found device at 0x22
/dev/iic2: found device at 0x23
/dev/iic2: found device at 0x24
/dev/iic2: found device at 0x25
/dev/iic2: found device at 0x26
/dev/iic2: found device at 0x27
/dev/iic2: found device at 0x29
/dev/iic2: found device at 0x2a
/dev/iic2: found device at 0x2b
/dev/iic2: found device at 0x2c
/dev/iic2: found device at 0x2d
/dev/iic2: found device at 0x2e
/dev/iic2: found device at 0x2f
/dev/iic2: found device at 0x30
/dev/iic2: found device at 0x31
/dev/iic2: found device at 0x32
/dev/iic2: found device at 0x33
/dev/iic2: found device at 0x34
/dev/iic2: found device at 0x35
/dev/iic2: found device at 0x36
/dev/iic2: found device at 0x38
/dev/iic2: found device at 0x39
/dev/iic2: found device at 0x3a
/dev/iic2: found device at 0x3b
/dev/iic2: found device at 0x3c
/dev/iic2: found device at 0x3d
/dev/iic2: found device at 0x3e
/dev/iic2: found device at 0x3f
/dev/iic2: found device at 0x40
/dev/iic2: found device at 0x41
/dev/iic2: found device at 0x42
/dev/iic2: found device at 0x43
/dev/iic2: found device at 0x44
/dev/iic2: found device at 0x45
/dev/iic2: found device at 0x46
/dev/iic2: found device at 0x47
/dev/iic2: found device at 0x4c
/dev/iic2: found device at 0x4d
/dev/iic2: found device at 0x4e
/dev/iic2: found device at 0x4f
/dev/iic2: found device at 0x50
/dev/iic2: found device at 0x51
/dev/iic2: found device at 0x52
/dev/iic2: found device at 0x53
/dev/iic2: found device at 0x54
/dev/iic2: found device at 0x55
/dev/iic2: found device at 0x56
/dev/iic2: found device at 0x57
/dev/iic2: found device at 0x58
/dev/iic2: found device at 0x59
/dev/iic2: found device at 0x5a
/dev/iic2: found device at 0x5b
/dev/iic2: found device at 0x5c
/dev/iic2: found device at 0x5d
/dev/iic2: found device at 0x5e
/dev/iic2: found device at 0x5f
/dev/iic2: found device at 0x60
/dev/iic2: found device at 0x62
/dev/iic2: found device at 0x63
/dev/iic2: found device at 0x64
/dev/iic2: found device at 0x65
/dev/iic2: found device at 0x66
/dev/iic2: found device at 0x67
/dev/iic2: found device at 0x68
/dev/iic2: found device at 0x69
/dev/iic2: found device at 0x6a
/dev/iic2: found device at 0x6b
/dev/iic2: found device at 0x6c
/dev/iic2: found device at 0x6d
/dev/iic2: found device at 0x6e
/dev/iic2: found device at 0x6f
/dev/iic2: found device at 0x70
/dev/iic2: found device at 0x71
/dev/iic2: found device at 0x72
/dev/iic2: found device at 0x73
/dev/iic2: found device at 0x74
/dev/iic2: found device at 0x75
/dev/iic2: found device at 0x76
/dev/iic2: found device at 0x77
/dev/iic2: 103 devices found
netbsd-raspaZeroW#

I also configured config.txt file (added last line):

netbsd-raspaZeroW# cat /boot/config.txt
#
upstream_kernel=1
os_prefix=dtb/
cmdline=../cmdline.txt
# UART settings, see https://www.raspberrypi.com/documentation/computers/configuration.html#configuring-uarts
enable_uart=1
force_turbo=0
# Default kernel for BCM2836 and later
kernel=/kernel7.img
# Override kernel for BCM2835 based boards
[pi0]
kernel=/kernel.img
[pi0w]
kernel=/kernel.img
[pi1]
kernel=/kernel.img
[all]
#
dtparam=i2c_arm=on
netbsd-raspaZeroW#

But the result is the same. Am I missing something?

Thanks so much.
Ramiro.