nrf51-ble-driver_win_0.4.0 question

[Royan]

I am using the PCA10031 as a serialisation device connected to a Windows laptop. The PCA10031 is programmed with connectivity_with_s120_1.0.1.hex and I am using the nrf51-ble-driver_win_0.4.0 driver.

I am sending about 70 20-byte packets per second (1400 bytes/second) from an nRF51822 to the PCA10031 using a custom service. I have written a C++ application but keep getting the following response about 20% of packets (i.e. 20% of packets were lost):

File: (null), Line: 0, Error code: 4

The number of errors tend to increase over time, which I speculate may be related to some overflowing buffers. I do not get the errors at low rates (10 packets per second).

What is this error and how can it be solved?

[Bjørn Inge]

Hi,
as you correctly mention, the error is caused by an internal buffer being overflowed. Data comes in faster than can be handled. You could try to reduce the risk of overflows by making the ble_event handling in your application as fast as possible.
Stability and performance will be continuously improved in future releases.

[Royan]

Hi Bjorn,

Thanks a lot for your swift response. Is the buffer overflowing on the received data (nRF51822 device to PCA10031) or transmitting data (PCA10031 to PC) side? The former means PCA10031 is too slow and I can't do much on my side apart from reducing the data rate while waiting for an updated driver. If it is the latter then I can try to optimise my C++ program further.

Thanks a lot.

[Bjørn Inge]

The overflow is most likely happening in the BLE Driver DLL for packets that are coming from pca10031 to the PC. There is probably not much you can do except lowering the data rate, reducing the time spent in the ble_event handler (in your C++ application) and waiting for improvements in the Driver.

[Royan]

Hi Bjorn, I have rewritten my C++ code (with circular buffering) and no longer getting the error indicated. Thanks a lot for your help. Just a note, would it be possible to document the error codes so that we need not ask Nordic when we encounter errors. Thanks a lot.

[Bjørn Inge]

Hi. I'm happy to hear that you were able to workaround the problem. Regarding the error codes, you will find them defined in the included header files. Error code 4 for instance is defined as NRF_ERROR_NO_MEM.