Coap server not working on a third party module

[kaushalyasat]

Hi, 

I am building the CoAP client and sever example programs on a third party module (Reytac MDBT50Q). I am using Reytac dev board  MDBT50Q-DB-40. Unfortunately the example apps doesnt seem to work. I am using NRF Connect SDK 2.0.0. I tried the apps on Nordic nRF52840 Dev Kits and they work. I am using the same nrf52840dk_nrf52840.dts file with the Reytac module. 

The Reytac dev board doesn't have the HFX oscillator on the dev board, probably it is available in the module itself. The dev board has a 32.7kHz crystal and is oscillating Vpp ~100mV. Dont know if this is too low. I couldnt find a spec for the LFXO in the datasheet.

When I look into the power supply on Dev board, I see VDDH tied to 3V3 and 10uH inductor between VDD and DCH. I reckon this means the power path would be 3V3->VDDH->REG0 DC/DC->REG1 (LDO or DC/DC)->System Power. I couldnt find the code section which handles the power control registers in coap client app. 

1. Is 100mV LFXO acceptable?
2. Where is power register configuration happens in coap client/server apps?

Thanks,

[Edvin]

Hello,

I tried having a look at the sniffer trace, but all the packets before ~200 are not decrypted properly when I open it in wireshark.

That goes for the packet above 93, except for the advertisements, and all the data request packets below 93. Is that the case for you as well? Do you know if the fe80::97b:a28b:5771:93bd is the minew device? And are you able to decrypt the packets in the log?

Or doesn't the Minew device affect the log at all, meaning the radio is silent from the Minew?

Best regards,

Edvin

[kaushalyasat]

Hey Edvin, Thanks for looking into this. 

I can see the "Expert Info (Warning/Undecoded): No encryption key set - can't decrypt" in some of the packets as well. 

But I found out something interesting in the debug terminal. 

When I connect P0.26 to GND, this happens.

[00:05:46.445,037] <inf> coap_client_utils: Send 'provisioning' request
[00:05:46.445,159] <err> os: ***** MPU FAULT *****
[00:05:46.445,190] <err> os:   Stacking error (context area might be not valid)
[00:05:46.445,220] <err> os: r0/a1:  0xaaaaaaaa  r1/a2:  0xaaaaaaaa  r2/a3:  0xaaaaaaaa
[00:05:46.445,251] <err> os: r3/a4:  0xaaaaaaaa r12/ip:  0xaaaaaaaa r14/lr:  0xaaaaaaaa
[00:05:46.445,251] <err> os:  xpsr:  0xaaaaaa00
[00:05:46.445,281] <err> os: s[ 0]:  0x00000000  s[ 1]:  0x00000000  s[ 2]:  0x00000000  s[ 3]:  0x00000000
[00:05:46.445,281] <err> os: s[ 4]:  0x00000000  s[ 5]:  0x00000000  s[ 6]:  0x00000000  s[ 7]:  0x00000000
[00:05:46.445,312] <err> os: s[ 8]:  0x00000000  s[ 9]:  0x00000000  s[10]:  0x00000000  s[11]:  0x00000000
[00:05:46.445,312] <err> os: s[12]:  0x00000000  s[13]:  0x00000000  s[14]:  0x00000000  s[15]:  0xffffffff
[00:05:46.445,343] <err> os: fpscr:  0x00000000
[00:05:46.445,373] <err> os: Faulting instruction address (r15/pc): 0xaaaaaaaa
[00:05:46.445,404] <err> os: >>> ZEPHYR FATAL ERROR 2: Stack overflow on CPU 0
[00:05:46.445,434] <err> os: Current thread: 0x20003880 (sysworkq)
[00:05:47.164,276] <err> fatal_error: Resetting system
uart:~$ *** Booting Zephyr OS build v3.0.99-ncs1  ***

What could this be?

[Edvin]

What is P0.26 doing in your application? Why did you try this? Do you see any logging without connecting P0.26 to GND? I see from your table that this is button4, so what does button4 do in your application? Does the same happen if you press button4 on the other module that is working?

BR,

Edvin

[kaushalyasat]

Hi Edvin, Thanks again. 

The reason for P0.26 is that in I dont have P0.25 in Minew module. So I changed the SW mapping in the DTS file. I created a custom board for the Minew module and changed the DTS file in that. To try to eliminate any uncertainties, I have removed all the other hardware interfaces apart from UART0 from the DTS as well. 

This stack overflow I see only when P0.26 is connected to GND.

In the other modules (Raytac and Nordic DK) I didn't have to modify the DTS as SW4 - P0.25 is available. Nothing like this happens in those, as the CoAP client/server was working with them.

Thanks,

[Edvin]

ok, let me rephrase my question. What does "button_3" do in your application, regardless of whether you are using the Raytac, Nordic or Minew module?