Increasing throughput for nrf52832

[Haresh05]

We are using nrf52832 with S132.

In our application, we have 1 device as central and it will connect to 4 peripheral devices.

Central device needs to send 128 bytes of data to each of 4 device at interval of 30 msec.

We have extended the data length to send 128 bytes in 1 packet.

Currently we are sending these packets at interval of 100 msec and still packets are getting dropped.

Connection interval is set to 7.5msec.

So how can we increase throughput to achieve our requirements?

[Haresh05]

I have checked the blog you provided. I was using the write with response. I changed it to write without response and the results are better now. Not exactly what we require but good for now.

After changing the connection and scan parameters, I have observed that the central device takes too long to establish a connection with peripheral devices as it immediately disconnects with reason:0x3e too often.

[Simonr]

Hi Haresh

A reoccurring 0x3E disconnect reason (connection failed to be established), is typically due to interference (for example other 2.4GHz devices such as the other devices you have connected if the connection parameters are set too small to handle multiple connection at the same time). It could also be interference on the nRF52832 board itself like oor antenna tuning, serial interfaces active close to the antenna, etc. 

My guess is that the connection parameters aren't optimal for connecting to 4 devices at the same time, so try tweaking these to see if you can remedy these disconnects. Also, what device are you using as a central in this setup?

Best regards,

Simon

[Haresh05]

Hi Simonr

We are using custom boards as central and peripheral devices. 

While testing there are nearly 50 devices in the surrounding using BLE. Central and Peripheral devices are placed 50ft apart.

Simonr said:

It could also be interference on the nRF52832 board itself like oor antenna tuning, serial interfaces active close to the antenna, etc. 

Can you provide any reference to the procedure to tune the antenna?

We are using UART for debugging purposes. Should we disable this for testing?

[Simonr]

Hi

The ~50 devices on the 2.4GHz bandwidth will likely make an impact on the throughput you're able to get, but you should still be able to connect and keep a connection alive just fine.

For antenna tuning, you can check out our whitepaper available on the matter here and make sure that our reference design matches your schematics and PCB design. We can also do a HW review for you if you'd like. If you do I can set this case to private mode so you can share the schematics and gerber files in this case and we can review them.

I don't think the UART should affect the throughput unless it is wired very close to the antenna, causing interference that way. 

Best regards,

Simon

[Haresh05]

Hi,

Simonr said:

The ~50 devices on the 2.4GHz bandwidth will likely make an impact on the throughput you're able to get, but you should still be able to connect and keep a connection alive just fine.

Can you provide any pointer to check for the connection issue as in our case it is taking too long to establish the connection?