UART communication issue thread

[pavan]

Hi All,

We are trying to interface nRF52840 based custom board, manufactured using Config 6 schematic as the reference, with R-Pi to work as NCP. Please refer to the attached schematic .

 

We found that the RPi was not able to communicate with the custom board, so when we tried to trace UART signal between R-Pi and our custom board as well as nRF-DK (nRF52840-DK 1.0.0), we found following results:

 

S. No.	Test	Result with nRF-DK	Debug mode Result with nRF-DK	Result with Custom board	Debug mode Result with Custom board
1	R-Pi Thread NCP Connectivity.	NCP  Connected	Device Running.	NCP  Not-Connected	Device Running.
2	UART TX Trace On J-Tag Reset without R-Pi connection.	Hex data : 7E 80 06 00 72 FC 57 7E	Device Running.	No data	Device Running.
3	UART TX Trace On Switch Reset without R-Pi connection.	Hex data : 7E 80 06 00 71 67 65 7E	Device Running.	No data	Device Running.
4	UART TX Trace On Power-Reset without R-Pi connection.	Hex data : 7E 80 06 00 70 EE 74 7E	Device Running.	Hex data : 7E 80 06 00 70 EE 74 7E	Device Running.

 

Note: --

    1) NCP firmware PATH:  SDK_DIR\examples\thread\ncp\ftd\uart\pca10056\blank\ses

    2) To verify if UART TX and RX is working, we used: SDK_DIR\examples\peripheral\uart\pca10056\blank\ses, and were able to verify that UART communication was working fine.

    3) UART TX and RX is checked on PIN P0.06 and P0.08 respectively of nRF-DK and custom board.

please suggest 

Thank you

PNordic_nRF52840.pdfavan S K

[pavan]

Hi ,

Problem was likely to be Hardware flow control.

We disabled the hardware flow control from NCP firmware and it is working now. Thank you.

 

will try to see if we can get it working with hardware flow control also. Please input if any suggestion regarding hardware flow control.

We have few queries:

1. What's the use of Hardware Flow Control in NCP?
2. Is it compulsory to have Hardware Flow Control in NCP?
3. If we disable Hardware Flow Control in NCP, will it effect NCP working or UART communication in any way?

Thanks in advance

Pavan s k

[Edvin]

pavan said:

What's the use of Hardware Flow Control in NCP?

 HWFC is used to ensure that the receiver is ready to/capable of receiving more UART packets. If the receiver is busy decoding the previous packet, then it will block the sender, and tell it to wait until it receives the "go" signal on the HWFC pins.

 

pavan said:

Is it compulsory to have Hardware Flow Control in NCP?

 I don't think so.

 

pavan said:

If we disable Hardware Flow Control in NCP, will it effect NCP working or UART communication in any way?

 It disables the feature that comes with HWFC. If the receiver is not ready to queue up more bytes on the UART, some UART data bytes may be lost if HWFC isn't enabled.