Any way to increase TX buffers on S110 (nrf51822) ?

[Ben Gray]

I've read that the number of tx buffers on the S110 is fixed at 6, however I've also read that this may be configurable on future versions of the softdevice (devzone.nordicsemi.com/.../

I can't find any API to set the tx buffers so I assume this never happened, can anyone confirm? I'm hoping there is some hidden option or magic version of the S110 that we could use with this limit increased. Any help would be greatly appreciated.

Unfortunately having only 6 TX buffers is a bit of a show stopper for my project. Our board runs in a noisy environment and often misses connection intervals, with only 6 buffers we can't recover in the next connection interval and have to drop packets.

(FWIW - using a TI chip we were able to push though more than 6 packets per connection interval and that gave us better immunity to noise and we therefore could maintain better bandwidth ...)

[Sigurd]

Hi,

You are unfortunately limited to 6 packets per connection interval with the nRF51-series SoftDevices.

On the newest nRF52-series SoftDevices you don’t have this limitation, and the SoftDevice is able to continue sending packets for the whole connection interval. With the nRF52 series you get a support for significantly higher throughput. With ATT MTU size set to 247 and LL payload size set to 251 you can achieve up to 771.1 kbps throughput in 1Mbps mode, and up to 1376.2 kbps in 2Mbps mode. See this link for more information.

[Ben Gray]

Thanks for the (very) quick reply. Although it's a bit disappointing ... guess I'll just have to push for a nRF52 chip :-).

[Sigurd]

A nRF52 series chip(especially nRF52832 and nRF52840) is definitely the way to go for the future. Compared to the nRF51, you have in the nRF52-series much lower power consumption, and lot more features(more flash and RAM, dedicated PWM hardware, NFC support, PDM/I2S,etc). You also get an updated SoftDevice with support for the new BLE 5 features such high throughput, advertising extensions and Improved coexistence with improved channel hop sequencing(Bluetooth 5 introduced an improved Channel Sequencing Algorithm (CSA #2) to improve the pseudo randomness of next hop channel sequencing. CSA #2 will improve coexistence performance of enabled devices in the presence of WiFi, other Bluetooth devices. All of the nRF52 Series SoCs have the ability to support CSA #2.)

Porting an existing application from the nRF51-series to the nRF52-series should not be any problem, and our community users are reporting porting time down to only a week. Also note that if you create a support ticket at MyPage, we can do PCB layout and design review, and we also do antenna tuning on your product for free.