Question from Bluetooth low energy Characteristics, a beginner's tutorial - challenge 2

RE: Question from Bluetooth low energy Characteristics, a beginner's tutorial - challenge 2

Marry — Fri, 10 Jul 2020 13:27:57 GMT

Hi. After reading more about this, i found out my answer. I'll leave it here, maybe others have the same issue: https://devzone.nordicsemi.com/f/nordic-q-a/12997/questions-on-the-temperature-sensor-tutorial-temp-conversion-and-decimal-numbers#post-id-74367

You basically take that number i.e. 118 and divide it by 4. That's all the trick. Thanks.

RE: Question from Bluetooth low energy Characteristics, a beginner's tutorial - challenge 2

Amanda Hsieh — Fri, 10 Jul 2020 12:17:25 GMT

Hi Marry,

You should search on Devzon for the similar questions like this retrieve-characteristic-value.

The support staff is reduced during the summer holidays, and you may experience delayed answers.

-Amanda H.

RE: Question from Bluetooth low energy Characteristics, a beginner's tutorial - challenge 2

Marry — Fri, 10 Jul 2020 11:40:58 GMT

Hi, Amanda Hsieh. After reading more about the temperature sensor, I found out that it actually measures the temperature inside the chip. Therefore maybe 118 degrees could be possible. Could you please tell me if this is the right way to read that value? Thank you in advance.

RE: Question from Bluetooth low energy Characteristics, a beginner's tutorial - challenge 2

Marry — Thu, 09 Jul 2020 11:49:21 GMT

Hello,

[quote userid="77782" url="~/f/nordic-q-a/63518/question-from-bluetooth-low-energy-characteristics-a-beginner-s-tutorial---challenge-2/259127"]See this post.[/quote]

Unfortunately, this does not answer my question. I was confused of how to interpret that value, since 0x76 means 118 dgr in decimal. And this post confirms what I thought, i.e. that I should convert the data from hexa to decimal. But still, I do not understand my 118 (decimal) degrees value.

Additionally, one could say that the last bytes (AA) are the temperature, but that's 170 dgr in decimal, therefore, it also does not make any sense.

RE: Question from Bluetooth low energy Characteristics, a beginner's tutorial - challenge 2

Amanda Hsieh — Thu, 09 Jul 2020 09:30:18 GMT

Hi Marry,

[quote user="Marry"]1. How should I interpret these values? Should I translate them from hexa to decimal? Although 0x76 means 118 dgr in decimal, so I guess there should be another trick.[/quote]

See this post.

[quote user="Marry"]2. Why are the first bits of the characteristic changed? I understood that the least significant bits should be changed, according to the different temperatures experienced by the sensor. [/quote]

You could use ble_gatts_hvx_params_t::offset to modify the offset within the attribute value. See this post.

-Amanda H.

RE: Question from Bluetooth low energy Characteristics, a beginner's tutorial - challenge 2

Marry — Wed, 08 Jul 2020 16:28:12 GMT

Hello Amanda,

And thanks for explaining me this! In the mobile app, it seems that every time I connect, I bond by-default. But it's good to know that this means an encrypted communication - thanks!

I have some new questions: going on with the same tutorial, I tried to send the values of the temperature to the application, as notification, but I am a bit confused:

1. How should I interpret these values? Should I translate them from hexa to decimal? Although 0x76 means 118 dgr in decimal, so I guess there should be another trick.

2. Why are the first bits of the characteristic changed? I understood that the least significant bits should be changed, according to the different temperatures experienced by the sensor. Please see the two attachments:

Thank you for noticing me regarding the summer-holidays delay.

Best regards, Marry

RE: Question from Bluetooth low energy Characteristics, a beginner's tutorial - challenge 2

Amanda Hsieh — Wed, 08 Jul 2020 13:29:37 GMT

Hi Marry,

If you click "Bond" in nRF Connect and bond with your kit you will automatically add encryption (ENC) to your BLE link.

The support staff is reduced during the summer holidays, and you may experience delayed answers.

-Amanda H.