getting max S132 connectivity fw throughput

RE: getting max S132 connectivity fw throughput

gkovelman_tap — Mon, 28 May 2018 07:07:40 GMT

Maybe there's just a quick fix to buffer multiple notifications on the nordic and then TXing them over UART as one large packet, reducing the handshake overhead.

If the changes are more than that, it'd probably be smarter to use an android/iphone 7 device as the central since they support DLE.

RE: getting max S132 connectivity fw throughput

hmolesworth — Mon, 28 May 2018 00:53:32 GMT

Queue the messages? I would suggest that you start by just chucking them away! Work out the available throughput by just ignoring all the received data and only then start looking at how that data can be shifted off the PCA10040 board. The uart is very inefficient and the hardware handshake is upside down as I mention elsewhere so not useful without hardware mods. To really shift data off the board you need one or more 8MHz SPI channels or something similar; if you are using something like this start by commenting out the call and see how much throughput increases.

I have a similar issue and just want to get the data to Wi-Fi; a Pi can give you an SPI connection, and it could even give you BLE direct if we could get it to work ..

static void ble_nus_chars_received_uart_print(uint8_t * p_data, uint16_t data_len)

RE: getting max S132 connectivity fw throughput

gkovelman_tap — Sun, 27 May 2018 07:33:46 GMT

Thanks for the answer.

Any suggestions on how to queue the message on the FW side?

RE: getting max S132 connectivity fw throughput

Bjørn Kvaale — Thu, 24 May 2018 07:00:15 GMT

Like I mentioned, we have done tests regarding this & it all points to the fact that the relaying of the UART via the JLink OB is the bottleneck. I would say you want to keep the connection interval as low as possible to increase throughput. Unfortunately, I am not sure it is practically possible to increase the throughput using the pc-ble-driver. It might work better if you are somehow able to have a buffer in your nrf device that is connected to the pc-ble-driver, which can store some of the data to allow a higher throughput. I am not sure this will work, but it might be worth a shot.

RE: getting max S132 connectivity fw throughput

gkovelman_tap — Wed, 23 May 2018 10:57:56 GMT

I tried routing the nRF52 to PC via an UART-to-USB adapter instead of the JLink OB, but throughput was the same, so it's not the JLink itself.

Increasing the connection interval and receiving multiple packets per connection interval should make it work. But it doesn't seem to do so with conn interval is higher.

Then, any idea on how to achieve high throughput? Could controlling the burstiness of the data on the peripheral side help with the pc-ble-driver design?

RE: getting max S132 connectivity fw throughput

Bjørn Kvaale — Tue, 22 May 2018 13:58:08 GMT

I have asked the developers of the pc_ble_driver to take a look at this case. Before I start asking you to start trying different things, I think it would be easier if they gave you some tips, as they are more experienced in regards to this firmware.

Update: As stated in this devzone case, the bottleneck in this case is the relaying of the UART via the JLink OB. The throughput via the pc_ble_driver will be quite low because of this. If you have a logic analyzer, you will be able to see the traffic over the UART lines & see more of the data flow between the pc & the connectivity FW.

RE: getting max S132 connectivity fw throughput

gkovelman_tap — Tue, 22 May 2018 12:57:40 GMT

Hi,

max event length is indeed at 320, like in that case.
High throughput is my guide for this activity. What I also tried, as high throughput demo suggested, was to change PHY to 2Mbps, but the actual throughput did not increase.

Connection interval of 7.5 didn't increase throughput; it's a little bit lower now, at ~38Kbps.

Connectivity FW is connectivity_2.0.1_1m_with_s132_5.0.hex. I'm not aware of other version that would with pc-ble-driver v3.0.1. Any other FW to try? Should I downgrade pc-ble-driver to 2.2.1? Let me know If I should put effort into it.

Thanks.

RE: getting max S132 connectivity fw throughput

Bjørn Kvaale — Tue, 22 May 2018 12:09:58 GMT

Regarding the NRF_ERROR_RESOURCES, this devzone case could be helpful. Have you taken a look at the high throughput demo? You should be able to get a lot more than 320 kbps. Might be useful to try a connection interval of 7.5 ms. What is the throughput then?

There might be an issue with the connectivity FW, but I am not sure about this. Have you tested with a different connectivity FW (for example the nrf connect connectivity FW when you open nrf connect)? Does that work?