UART Rx bytes keep on increasing

[mayank_patel]

Hi All,

I'm using hci interface to scan the ble based beacons.

While scanning hci interface's Rx bytes keep on increasing because beacons are being scanned.

I'm using tcflush() function with TCIOFLUSH option to flush the UART.

UART flush i'm doing after every 10 sec scanning window finishes & tcflush() fun gets success also.

Still, Instead of decrease in Rx byte number it goes up continuously. So I'm doubting that whether the UART buffer is flushed or not?

This is causing beacon scanning to stop after the "Rx bytes" reaches some max value.

You can see the below snap i have taken from my terminal.

root@device-imx6ull:~# hciconfig
hci0: Type: Primary Bus: UART
BD Address: 00:00:00:00:00:00 ACL MTU: 27:7 SCO MTU: 0:0
UP RUNNING
RX bytes:579483 acl:0 sco:0 events:20484 errors:0
TX bytes:295 acl:0 sco:0 commands:40 errors:0

Q: I'm flushing the buffer in correct way or do i need to get some attr first and then flush the UART.

Thanks,

Mayank

[Jørgen Holmefjord]

Hi,

Do you use any Nordic products with the HCI interface? This sounds like a question you should direct to a Linux forum, as they will have much more experience with this.

Best regards,
Jørgen

[Jørgen Holmefjord]

Ok, I understand. But the i.MX 6ULL application processor is running some kind of embedded Linux, right? And your question is about flushing of the UART buffer on the NXP side, and not on the Nordic/Zephyr HCI side?

[mayank_patel]

Yes custom board is running an embedded linux.

I am assuming that whatever I'm seeing using 'hciconfig' command, it's just a statistics. So i can't expect Rx bytes to restart from 0 after successful flushing the UART. So flushing part seems ok.

I have a doubt in zephyr's hci_uart sample app. Whether that has some buffer limitation or what.

Because "hcitool lescan --duplicates" cli also stops scanning the beacons after some time.