RSSI and RSRP on THINGY.91

[Hoang]

Dear, 

Im trying to measure the RSSI with THINGY:91, I found on the document  nrf91_at_commands_v1.1.pdf about

1. AT+CSQ

      +CSQ: <rssi>,<ber>

Note: Not detectable, RAT not supported. Use +CESQ and %CESQ for E-UTRA signal quality.

2. AT + CESQ 

    +CESQ: <rxlev>,<ber>,<rscp>,<ecno>,<rsrq>,<rsrp>

<rsrp>
0 – RSRP < −140 dBm
1 – When −140 dBm ≤ RSRP < −139 dBm
2 – When −139 dBm ≤ RSRP < −138 dBm
...
95 – When −46 dBm ≤ RSRP < −45 dBm
96 – When −45 dBm ≤ RSRP < −44 dBm
97 – When −44 dBm ≤ RSRP
255 – Not known or not detectable

I am using AT+CESQ to find RSRP 

and, i found some document about RSRP range: 

https://wiki.teltonika.lt/view/RSRP_and_RSRQ

But, when I tested to measure it, i got: 

I set the devices (3) in my freezer, and got the RSRP < -100dBm, 

is it conflict here? On the document, they say: NO signal when RSRP < -100dBm, but, I measured -120dBm, and I still received the data from my THINGY:91 - it means : still signal 

I am using Telia NB-IOT( Unit1) Telia LTE-M(Unit2) and Telenor LTE-M(Unit3)

My question is: RSRP vs Signal strength range? RSRP for no signal?

Thanks 

BR, 

Hoang Nguyen

[Hoang]

I can send you the whole source_code if i have time to review it

[Hoang]

Dear Hakon

I found my problem: 

I couldnt reboot:

I got the error when i tried to run sys_reboot(0);  ( #include <misc/reboot.h> )

void sys_reboot(int type)
{
        printk("STATE: error_handler/sys_reboot \n\r"); 
	(void)irq_lock();
         printk("STATE: error_handler/sys_reboot/ irq_lock \n\r"); 
#ifdef CONFIG_SYS_CLOCK_EXISTS
	sys_clock_disable();
#endif
         printk("STATE: error_handler/sys_reboot/ sys_arch_reboot \n\r"); 
	sys_arch_reboot(type);

	/* should never get here */
	printk("Failed to reboot: spinning endlessly...\n");
	for (;;) {
		k_cpu_idle();
	}
}

error:

Exception occurred in Secure State
***** HARD FAULT *****
  Fault escalation (see below)
***** BUS FAULT *****
  Precise data bus error
  BFAR Address: 0x50008120
***** Hardware exception *****
Current thread ID = 0x2002abec
Faulting instruction address = 0x74b056ee
Fatal fault in ISR! Spinning...

Plz help me

[Hakon]

What happens if you just try to call NVIC_SystemReset() instead?

[Hoang]

Thanks for suggestion, i will try it later

[Hoang]

Dear Hakon, 

Hakon said:

NVIC_SystemReset

I tried NVIC_SystemReset(), after modem_configure(), 1time, then, my THINGY:91 has a problem: 

Connecting to LTE network. This may take several minutes.
[00:00:28.564,514] [1B][0m<dbg> lte_lc.at_handler: recv: +CEREG: 2,"9D6D","0125DF64",9
[1B][0m
[00:00:32.653,900] [1B][0m<dbg> lte_lc.at_handler: recv: +CEREG: 4,"9D6D","0125DF64",9
[1B][0m
[00:01:31.799,346] [1B][0m<dbg> lte_lc.at_handler: recv: +CEREG: 4,"FFFE","FFFFFFFF",9
[1B][0m
[00:01:58.508,422] [1B][0m<dbg> lte_lc.at_handler: recv: +CEREG: 2,"0C98","01FEC912",9
[1B][0m
[00:02:25.204,986] [1B][0m<dbg> lte_lc.at_handler: recv: +CEREG: 2,"FFFE","FFFFFFFF",9
[1B][0m

It couldnt do anything else now, just stuck here. Could you plz tell me why?

I want to reset my THINGY:91. 

Mvh

Hoang