Color sensor pca20035

[Hoang]

Dear, 

I am using thingy:91 pca20035 and try to test the color sensor BH1749NUC

I tried to run the /samples/sensor/bh1749

I got the output: 

SPM: NS image at 0xc000
SPM: NS MSP at 0x20020a78
SPM: NS reset vector at 0xde51
SPM: prepare to jump to Non-Secure image.
***** Booting Zephyr OS build v1.14.99-ncs3-snapshot2-1270-gb1d603491de8 *****
device is 0x20021d9c, name is BH1749
[00:00:00.004,913] [1B][0m<inf> BH1749: BH1749 initialized[1B][0m

I expected it will return the color in process(dev); but I got nothing. 

Do I need to do some "trigger" to enable sensor? 

Thanks, 

BR, 

Hoang Nguyen

[Simon]

The reason you're not getting any input is because it's stuck at process(..)→while(1)→k_sem_take(..). In order for the program to continue from there, k_sem_give(..) has to be called (this is because the count it zero, and the give function will increase it, read more about semaphores here). In trigger_handler(..) this function is called, and it will allow the program to continue.

When I ran the program, the trigger function was never called, I am not sure why, since sensor_trigger_set() executed without any errors. It might be something wrong with the configuration of the bh1479 sensor, and it will never trigger GPIO PIN 27.

However, I was able to make the sensor work by disabling triggering, which can be done by setting CONFIG_BH1749_TRIGGER=n in prj.conf. Then you have to call sensor_sample_fetch_chan(..) followed by sensor_channel_get(..) at regular intervals.

If you would like to use the sensor in interrupt mode, I can look into it.

Best regards,

Simon

[Hoang]

Hello @Simon 

Are you there?

[Hoang]

hi Simon, 

I tried to combine bh1749 source code to asset_tracker, and it works

But, I didnt work when it stood alone

Thanks, 

BR, 

Hoang Nguyen

[Simon]

Strange.. Do you need to make it work alone, or should we consider this case resolved?

Best regards,

Simon

[Hoang]

With me, I want to make it clean, I want to know why it couldn't work when it stands alone. 

then, i can understand more clearly about sensor api. but no rush, if you are so busy. 

Thanks, 

BR, 

Hoang Nguyen

[Simon]

Okay, I will look into it and get to the bottom of it as soon as I have handled some other tasks.

Best regards,

Simon

[Simon]

I think I found a fix to this. After some attempts, I was only able to get the example working when I started a debugging session through SES.

This is because the program stops at the start of main(), after all the zephyr initialization happens, and you'll have to manually continue the program from there.

I tried to add k_sleep(500) in the start of main, and flash the program without any debugging, and it worked. Try this fix, and check if you're able to make it work.

I'll take a deeper look into this and figure why a delay is necessary, and report back to you when I figure it out.

Best regards,

Simon