LP-CC1352P7: Minimum reporting interval in senor/collector example for 915MHz and 868MHz

Hi Andreas,

1. What version of the SimpleLink SDK are you using?

2. Are you using beacon mode, non-beacon mode or frequency hopping mode?

3. Sounds like your testing with just one sensor and one collector? (Or do you have several sensors connected?)

When We test the TI 15.4-Stack, we only test down to 10 s reporting interval. We don't recommend going below this, however we have seen successful customer implementations at much lower reporting intervals.

Can you post a sniffer log of the 868 MHz case?

Cheers,

Marie H

Hi Marie,

I am using the SimpleLink SDK 5.40.0040.
At the moment I am using the non-beacon mode.
Yes, I am only testing with one sensor and one collector.

I did not setup a sniffer yet, but I monitored the signal by mapping the LNA enable  and the Tx start signals to GPIOs.
For the 915MHz band I can observe regular activity at a 100ms interval as expected, but for the 868MHz band I see activity at  110ms interval.

Best regards,

Andreas

Hi Andreas,

Can you tell me what code changes or sysconfig changes you made to change the reporting interval (on both sensor and collector side)?

If you could post your logic trace I would be interested to see that as well.

Cheers,

Marie H

Hi Marie,

To make it easier I imported a fresh version of the senor and collector project from the SDK. I did not do any changes besides changing reporting interval to 100 ms in sysconfig and selecting the frequency band 915MHz or 868MHz. I added these lines in main.c after the Board_init() to monitor LNA and Tx activity on the sensor: 

// Map LNA enable pin RFC_GPO0 to DIO9
IOCPortConfigureSet(IOID_9, IOC_PORT_RFC_GPO0,
IOC_IOMODE_NORMAL);
// Map Tx start pin RFC_GPO3 to DIO11
IOCPortConfigureSet(IOID_11, IOC_PORT_RFC_GPO3,
IOC_IOMODE_NORMAL);

Scope shoot 1: 915 MHz band at 50ksps in No Beacon mode: See activity at 10 Hz

Scope shoot 1: 868 MHz band at 50ksps in No Beacon mode: See activity at ~8 Hz

Best regard,

Andreas

Hi Andreas,

There are a couple of differences between the 868 and 915 band, e.g. on 915 (NA) band CSMA/CA is used, while on the 868 (EU) band LBT is used. This is contributing to your increased interval. 

If your main goal is to achieve 100 ms reporting interval on both PHYs, you may need to choose a lower value for the parameter for the EU band. Have you done a test e.g. with 90 ms?

Cheers,

Marie H

Hi Marie,

Understood, I will do some more testing beginning of next week and have a look if this will work,

Thanks for your support!

Best regards,

Andreas

Hi Marie,

I did test different reporting interval settings below 100ms , like 90ms or 50ms but got the same behavior as in the screenshots above.

Here some further tests:

1. shortened the senor message to a absolute minimum, by changing the CONFIG_FRAME_CONTROL in collector.h to:

#define CONFIG_FRAME_CONTROL (Smsgs_dataFields_tempSensor | \
Smsgs_dataFields_configSettings)

This got me a minor improvement from 7.7Hz to 8.2Hz. 

2. Increasing the senor message by 64 Byte changed the interval to 7.2 Hz

3. Increasing the phy type to 200ksps brought a slight improvement. I was able to reach 9Hz with the reduced senor message.

4. While testing I also switched back to the 915MHz band and I could push this to a reporting interval of 20 Hz (50ms).

What improvements can I further implement or does this mean I just cannot reach 10Hz reporting interval on the 868MHz band because of some fundamental differences like LBT vs CSMA/CA?

Best regards,

Andreas

Hi Andreas,

Did you do any testing with setting different reporting intervals?

SysCOnfig -> TI 15.4-Stack -> Network -> Application -> Reporting Interval and sensor.c:

/* Reporting Interval Min and Max (in milliseconds) */
#define MIN_REPORTING_INTERVAL 1000
#define MAX_REPORTING_INTERVAL 360000

Cheers,

Marie H

Hi Marie,

Yes I adjusted this code to 50 ms.

#define MIN_REPORTING_INTERVAL 50

and then tested 50ms 70 ms and 100ms reporting intervals set in the sysconfig.

Best regards,

Andreas

Hi Andreas,

Did you see any difference when setting 50 ms, vs 70 ms vs 100 ms?

Cheers,

Marie H

Hi Marie,

No I do not see a difference in behavior for 50 ms, 70 ms or 90 ms.
I only got some improvements by reducing the length of the sensor message.

Best regards,

Andreas