CCS/CC2650: the RF connection discontinously on test board

Luong The Phong

Part Number: CC2650

Tool/software: Code Composer Studio

I design test board and load sample source code simplepheral ble stack 2.1.0. Board and app on smartphone are lost connect every 40 second. Can you show me how to do not lose the connection?

over 6 years ago

0 Fredrik K over 6 years ago

TI__Guru** 106705 points

Hi Luong,

This issue is most likely caused by incorrect tuning of the 32.768 kHz crystal. If the 32k crystal oscillator is off, the device will not be able to time the connection events properly and the connection will be terminated.

Refer to section 6.3 in www.ti.com/lit/pdf/swra640 for details.

Regards,
Fredrik

0 Luong The Phong over 6 years ago in reply to Fredrik K

Intellectual 610 points

I use crystal TSX-3225 24.0000MF15X-AC3 as ref design guide

0 Luong The Phong over 6 years ago in reply to Luong The Phong

Intellectual 610 points

I don't use crystal 23k in board. Do not know whether it affects anything?

0 YiKai Chen over 6 years ago in reply to Luong The Phong

Guru 735685 points

I don't know why my previous reply is remove but you should check 24-MHz Crystal to see if it is within a maximum 40-ppm total tolerance. You can refer to section 5.2.1 24-MHz Crystal in www.ti.com.cn/.../swra495f.pdf

0 Fredrik K over 6 years ago in reply to YiKai Chen

TI__Guru** 106705 points

Hi YiKai,

I deleted your original post because problems with dropped connections as described here are not because of inaccurate 24 MHz crystal. As I wrote in my reply, this problem comes from timing issues and is thus due to poorly tuned 32k crystal.

It is of course important to make sure the 24 MHz crystal is well tuned also, but the problems resulting from a 24 MHz frequency offset would lead to other types of failures.

Regards,
Fredrik

0 Fredrik K over 6 years ago in reply to Luong The Phong

TI__Guru** 106705 points

Hi Luong,

If you are not using 32k crystal in your design, you must make sure you are enabling calibration of the 32k RC oscillator as described here: www.ti.com/.../swra499

Regards,
Fredrik