How to read nrf sniffer 4.1.0 serial data in C?

RE: How to read nrf sniffer 4.1.0 serial data in C?

Amanda Hsieh — Fri, 25 Feb 2022 12:42:05 GMT

Hi,

True, we use python and not C. Can't really help you with making it work with C.

However, there is an open-source application in C already that uses the sniffer UART protocol.

You might have a look here: https://github.com/homewsn/bsniffhub

-Amanda

RE: How to read nrf sniffer 4.1.0 serial data in C?

Matthew C Clark — Thu, 24 Feb 2022 17:30:31 GMT

Yes, I found that last night. Right now my main issue is that when I try to read the fd via:

res = read(localnrf->fd, buf, 255);

I get the buffers of random lengths listed above. I've not been able to find a simple C example that properly manages it. Wireshark uses your python interface.

RE: How to read nrf sniffer 4.1.0 serial data in C?

Amanda Hsieh — Thu, 24 Feb 2022 08:54:00 GMT

Hi,

In the 4.1.0 release in the doc folder there is a sniffer_uart_protocol.txt document that you can use.

-Amanda

RE: How to read nrf sniffer 4.1.0 serial data in C?

Matthew C Clark — Wed, 23 Feb 2022 21:12:55 GMT

Following up a bit, I managed to play with settings to get data across the line. Though the serial read is still a bit wonky as I get varying buffer sizes (see below), it appears at least for the nRF51, you're using SLIP for packet coding? The code looks for 0xAB (SLIP_START) and 0xBC (SLIP_END). Is this correct?

buf_rx_len = 4 0xBC 0xAB 0x2B 0x0
buf_rx_len = 2 0x3 0xB6
buf_rx_len = 1 0x23
buf_rx_len = 3 0x2 0xA 0x1
buf_rx_len = 2 0x26 0x54
buf_rx_len = 3 0x0 0x0 0x39
buf_rx_len = 2 0xCB 0x5
buf_rx_len = 1 0xB
buf_rx_len = 4 0xD6 0xBE 0x89 0x8E
buf_rx_len = 1 0x0
buf_rx_len = 4 0x17 0x0 0xCA 0x91
buf_rx_len = 2 0x2F 0x85
buf_rx_len = 1 0x4A
buf_rx_len = 3 0x6C 0x2 0x1
buf_rx_len = 3 0x1A 0x2 0xA
buf_rx_len = 2 0xC 0xA
buf_rx_len = 1 0xFF
buf_rx_len = 3 0x4C 0x0 0x10
buf_rx_len = 2 0x5 0xA
buf_rx_len = 2 0x14 0x33
buf_rx_len = 2 0x3C 0x76
buf_rx_len = 3 0xF5 0x2B 0x92
buf_rx_len = 1 0xBC
buf_rx_len = 3 0xAB 0x2B 0x0

RE: How to read nrf sniffer 4.1.0 serial data in C?

Matthew C Clark — Wed, 23 Feb 2022 14:41:47 GMT

Thanks, Amanda, I'll give that a try. If it helps, this is the code in kismet that attempts to open /dev/ttyACM0 where my nRF attaches. If there are any settings you know that should be on/off, please let me know?

/* open for r/w but no tty */
localnrf->fd = open(device, O_RDWR | O_NOCTTY);

if (localnrf->fd < 0) {
snprintf(msg, STATUS_MAX, "%s failed to open serial device - %s",
localnrf->name, strerror(errno));
return -1;
}

/* save current serial port settings */
tcgetattr(localnrf->fd,&localnrf->oldtio);

/* clear struct for new port settings */
bzero(&localnrf->newtio,sizeof(localnrf->newtio));

/* set the baud rate and flags */
localnrf->newtio.c_cflag = localnrf->baudrate | CRTSCTS | CS8 | CLOCAL | CREAD;

/* ignore parity errors */
localnrf->newtio.c_iflag = IGNPAR;

/* raw output */
localnrf->newtio.c_oflag = 0;

/* newtio.c_lflag = ICANON; */

/* flush and set up */
tcflush(localnrf->fd, TCIFLUSH);
tcsetattr(localnrf->fd, TCSANOW, &localnrf->newtio);

return 1;

RE: How to read nrf sniffer 4.1.0 serial data in C?

Amanda Hsieh — Wed, 23 Feb 2022 12:35:38 GMT

Hi,

The speed should be 1M (1000000).

Flow control does not really matter since it is a virtual COM port. However, HW FC is on between the VCOM and the nRF COM. The argument provided to stty will not have any effect.

Regards,
Amanda