TTL HMI to NRF52840

[MontanaEE]

Working with a Pinnacle 100 using an NRF52840.  I have a HMI with a TTL serial interface.  I have verified I/O on the HMI itself via a TTL/USB converter to Tera term, but having trouble with TTL comm to the NRF.  Is there sample code available to reference for setting up the port for this.

[MontanaEE]

I am using the Laird Connectivity Pinnacle 100 DVK.  https://docs.zephyrproject.org/latest/boards/arm/pinnacle_100_dvk/doc/index.html

This DVK uses Zephyr RTOS.  I am a first time Zephyr user so picking that up as I work through this.

I have a UART available on the DVK, but I do not see the data from the touchscreen coming in on the port.  I can connect the same touchscreen to a TTL to USB converter and see the touchpoint ID's come through on TeraTerm with no issue,  so I know that is functioning.  There is a direct USB port to the NRF52840 on the DVK.  Is there a way to monitor the other UART port to see what is coming through besides just getting the echo back on the port?  This is a 3.3V TTL signal which should be compatible with the UART I believe.

[MontanaEE]

The SDK version I have is 2.5.0

[JONATHAN LL]

MontanaEE said:

Is there a way to monitor the other UART port to see what is coming through besides just getting the echo back on the port? 

Do you have a logic analyzer or a Oscilloscope that you can probe the lines with to see what is happening on the line? 

TP 13 and TP 14 is USB lines test points. 




Regards,
Jonathan

[MontanaEE]

Jonathan,

Thank you for the response.  Yes, I do have an o'scope.  The board I am using is the Laird Pinnacle 100 DVK.  It has a UART port that I can access the TX/RX pins on.  Am I correct that for the 3.3V TTL Serial, I would connect to the UART TX and RX?    If so, I was trying to find out how to view the data so I can debug the HMI.

Thanks,

Stephen

[Sigurd]

Hi,

Jonathan is out of office, so I'm replying instead.

MontanaEE said:

Am I correct that for the 3.3V TTL Serial, I would connect to the UART TX and RX? 

Correct.

MontanaEE said:

If so, I was trying to find out how to view the data so I can debug the HMI.

Personally, I prefer saleae logic analyzer, but there are other options on the marked as well.

[MontanaEE]

Thank you.  I will see what I can find for an LA.  I have everything connected as it should be then.

[JONATHAN LL]

Both the Analog Discovery and Saleae works well as logic analyzers but I do see that there are some makeshift Arduino options like this https://www.hackster.io/vincenzo-g/diy-logic-analyzer-f61ee5 that doesn't brake the bank. 

Whatever you end up using should help with further debugging. 

Regards,
Jonathan

[MontanaEE]

Hey Jonathan,

 I have this setup for the two wire TX/RX on my display to connect to the nrf52840.

 

        uart0_default_alt: uart0_default_alt {

            phandle = < 0x2 >;

            group1 {

                psels = < 0x6 >, < 0x10008 >;

            };

        };

        uart0_sleep_alt: uart0_sleep_alt {

            phandle = < 0x3 >;

            group1 {

                psels = < 0x6 >, < 0x10008 >;

                low-power-enable;

            };

        };

I do know what the signal looks like with the o'scope now.  What is the best way to receive this in?  I'm thinking of bringing it in as a string, but I need to send and receive in the same format.  Below is the signal I receive for a single touchscreen press.  Each button is it's own unique number always ending in FF FF FF.

Stephen

[JONATHAN LL]

MontanaEE said:

What is the best way to receive this in?  I'm thinking of bringing it in as a string, but I need to send and receive in the same format. 

You just have to select one, not sure if one is better then the other, hex or string will both work. 

Regards,
Jonathan