Is BLE_GAP_PHY_CODED using the S=2 or the S=8 coding?

[Tobias Schneider]

Hi,

the nRF5 SDK v13.0.0-1.alpha uses the BLE_GAP_PHY_CODED constant to indicate a coded PHY.

The BLE 5.0 standard specifies two options for coding: S=2 (500 kbit/s) and S=8 (125 kbit/s).

Which one of these does BLE_GAP_PHY_CODED enable?

Regards Tobias

[Sigurd]

Hi,

The BLE_GAP_PHY_CODED option enables S=8 coding (125 kbit/s), this is the option that will give you the longest range.

[Sigurd]

Hi Christian,

We are still working on the implementation of S=2. It will probably be released together with the production variants of the nRF52840 in Q4 2017.

[l_kamp]

Sorry to warm up this old topic, but is it possible now to use S=2 on an NRF52840 with SoftDevice S140? I looked at the API but can only find the BLE_GAP_PHY_CODED PHY, no way to specify S=2 or S=8.

[Sigurd]

Hi,

The S140 version 6.0.0 SoftDevice does not have full support for S=2 (500 kbps). The application cannot select S=2, so all packets are transmitted using S=8 when Coded PHY is used. However, the nRF can receive both S=2 and S=8 coded packets from the peer.

[cedric pi]

Hi,

The S140_nrf52_6.1.0 release notes document says that this SoftDevice supports S=2 coding scheme since version 6.0.0. It also says that version 5.0.0-2.alpha supports S=8 coding scheme only.

I use two applications to perform some tests. The first application is using nRF5_SDK14.2.0 and the SoftDevice S140_nrf52_5.0.0-2.alpha while the second one is using nRF5_SDK15.0.0 and the SoftDevice S140_nrf52_6.1.0.

When both applications are configured with BLE_GAP_PHY_1MBPS (set using sd_ble_phy_request function, checked using BLE_GAP_EVT_PHY_UPDATE event), the disconnection appears at the same point.

When both applications are configured with BLE_GAP_PHY_CODED, the one using S140_nrf52_5.0.0-2.alpha  reaches a farther point than the one using S140_nrf52_6.1.0. (S140v5 is about twice more efficient than S140v6).

From these results, I am wondering if S140_nrf52_6.1.0. uses the S=2 coding scheme and if so, is there a way to configure the S=8 coding scheme like in the S140_nrf52_5.0.0-2.alpha ?

Regards,

[Sigurd]

cedric pi said:

When both applications are configured with BLE_GAP_PHY_CODED, the one using S140_nrf52_5.0.0-2.alpha  reaches a farther point than the one using S140_nrf52_6.1.0. (S140v5 is about twice more efficient than S140v6).

You mean that you are getting better range with the 5.0.0-2-alpha?

Please make sure that you are using nRF52840 DK version 1.0.0 (nRF52840 production silicon) when testing the S140 v6.1.0. 

cedric pi said:

From these results, I am wondering if S140_nrf52_6.1.0. uses the S=2 coding scheme and if so, is there a way to configure the S=8 coding scheme like in the S140_nrf52_5.0.0-2.alpha ?

S140 V6.1 can receive both S=2 and S=8, but it will only send S=8 when configured with BLE_GAP_PHY_CODED. That means that you are already using S=8 when sending data between 2 nRF52840 devices.