reading BH1750 lightsensor with Atmega328P using i2c /TWI

Sebastian wrote:
> Automotive

UNO Automotive µC ?
No! (?)

Sebastian wrote:

> #define I2C_WRITE 0;

All these semicolons in defines are plain wrong.

leo

so you are saying the datasheet is wrong? because thats the one our 
prof. was using.

leo wrote:
> Sebastian wrote:
>
>> #define I2C_WRITE 0;
>
> All these semicolons in defines are plain wrong.
>
> leo

removed them but i doubt it made a difference couldnt see any

Sebastian wrote:
> removed them but i doubt it made a difference couldnt see any

Yes, it did work by chance. Though I didn't look further as you have 
likely more C-related errors in the code. And yes ...

>   TWBR = ((16000000 / 100000) -16) / 2;

That may overflow. Compare to the F_CPU define.

leo

Don´t know this Sensor, but it seems to be the wrong Address.

Low - 0x23
High - 0x5C

Simply try to change the Code from

1

uint8_t SLA_W = 0x5C; // Address from slave + write (which is +0) // 0x5c because i found it in the Internet not in data sheet.

to

1

uint8_t SLA_W = 0x23; // Address from slave + write (which is +0) // 0x5c because i found it in the Internet not in data sheet.

I tryd both with 0x5C i get to the following point:
start condition
send address
specify register
switch master to read
read first message
waiting for completion of read...

with 0x23 i get the following:
start condition
send address
specify register

but you are right it should be 0x23 because i connected ADDR pin to 
ground at least thats something i read. Maybe the register 0x10

[SOLVED]
Ok i got it working now. The major issue was that the address i used was 
wrong. The solution was basically at Page 7 of the BH1750 datasheet. 
There i found an example with address bites that worked.

I also added ACK accordingly and some status checking for debugging.
And i completely removed the ADDR wiring so the ADDR Pin of the BH1750 
has now no connection at all.

I attached the working code as LightSensorRead.c .

thanks for the comments.