STM32WB HSE tune

[msemegen]

Hi,

What error on HSE frequency is acceptable by STM32WB35? More than 1 kHz can disturb connection process (its interrupted or it's slow than usual on some phones) or can cause unexpected disconnection? 

Does this affect the range of the advertisement ?

Best,
msemegen

[TDK]

Per the datasheet:

50 ppm for Bluetooth Low Energy, 40 ppm for 802.15.4 and when both Bluetooth Low Energy and 802.15.4 are used.

[msemegen]

According to this calculator https://www.everythingrf.com/rf-calculators/ppm-to-hz-calculator currently we are at 57 ppm level (~18000 Hz). Using hse tune techniques we can lower it to 47 ppm (which is a little bit lower than maximum error). 47 ppm will be good enough?

[TDK · Accepted solution]

Are you using 802.15.4? If so, then no.

Even if you're just using BLE, if it were my product, I wouldn't ship something that had 47 ppm off if the limit was ±50 ppm. Things will drift with time and temperature.