Multi-digit word variable to string

[richard]

Shouldnt we write first and then read? ok i understand that we have nothing to write. But why it doent work if i do not add the i2cwrite line?

which is precisely what the i2cread command does for you automatically. it should not ever be necessary to add a extra write , no i2c chip i have ever encountered has needed such treatment

i2cwrite SDA, SCL, addr

is an incomplete transaction. if your chip needs it then it is not a true i2c device or something else is occurring.
a logic analyzer would show what's really happening. its not normal and should be examined further to have any confidence
that the code is really viable in the long term

addr = %10110100

trying to set bit0 [the r/w bit] of a i2c address with pbp's i2c commands is not possible and will not have any effect
the code will set the r/w bit as needed

[richard]

it could be the chip is not really i2c and behaves differently

try this, at least its a nicer transaction
i2cwrite SDA, SCL, addr,[7]
i2cread SDA, SCL, addr,[TEMP.lowbyte, TEMP.highbyte]



looking at the wiki link you posted, this would do exactly what the smbus timing diagram describes as a proceedure

PEC var byte
i2cread SDA, SCL,addr,reg,[temp.lowbyte,temp.highbyte,PEC] ' reg = $07 ;would be the normal pbp way

worth trying

[astanapane]

Hi Richard,

sure i'll try that, and i will try to figure out what is going on with a logic analyzer.

I have a saleae logic 8.

Will try that later today. Many thanks for your time once again.

[richard]

If there is only one MLX90614 sensor, the 7-bits address is 0x00 by default.

according to wiki addr =0 where did you get B4 from ?

[Ioannis]

If the chip is the MAX30102, on page 16 seems that reading needs first a write.

Ioannis

[astanapane]

If the chip is the MAX30102, on page 16 seems that reading needs first a write.

Ioannis

it is an IR MLX90614

[astanapane]

Applying the 0x00 is not working.

When i add back the B4 or B5 for write or read mode correspondingly, everything is in a working order again.

[richard]

Its hard to work with crappy information




i2cread SDA, SCL,$b4,7,[temp.lowbyte,temp.highbyte,PEC] will do exactly that


i just realized that what code you posted is in fact a snippet .
addr and reg are never defined , osc is unknown ,i2c defines unknown, pin settings and i2c pull ups ...........

could be another waste of time

[astanapane]

wait a sec,

im reading the manual again from the SENSOR

https://www.waveshare.com/w/upload/e/e4/MLX90614-EN.pdf