I2C library functions to send a single measurement request command

Hi, there am attempting to communicate with aHoneywell Humidity sensor that has i2c port.
The part is always in sleep mode unit it gets a measurement request command, which is a single byte
I2C Measurement Request Format
Start A6 A5 A4 A3 A2 A1 A0 0 ACK stop
Can this be done with any existing command, or do I have to start bitbanging and implement my own i2c .

Have you had a look at the docs?

Thanks for suggestion, I had a quick look in the firmware troubleshooting , saw nothing of relevance.
I was just wondering if the standard commands can be manipulated easily to just apply start condition,slave address , a write bit =0 from photon,. followed by ack from slave , followed by stop from photon.
Is it possible to get source code for i2c library functions?

What you’re describing is standard I2C, and you can just use the I2C API:


It’s implemented in the STM32F205 hardware, so it’s not like there’s a library you can modify, but you shouldn’t need to.

1 Like

While @rickkas7 has already provided the link, the search feature in the docs (top of page)

feature a Search field
like here
which when entering I2C would render this

What is the name of the Honeywell Sensor you are using?

Maybe there is a working library already written for it which would be easy to get going with.

I know for sure there are other sensors that have libraries ready to use.

I enclose link to honeywell i2c and 6100 series datasheetp


I found this Arduino library with a quick search.


Looks like these chips are pretty old, I would consider something more updated and accurate if you’re up for trying something new.

I like these:

There is a ready to go library for the Particle Platform for this chip also.


Thanks for all the useful help guides.
Spent an hour last night and got it going.
So got Sensirion and Honeywell I2C digital humidity/temp sensors code up and running and can share out if anyone interested.

1 Like