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CC2540: Question about CC2540

Jimmy Huang
Genius 3585 points
Part Number: CC2540


Hello:

The customer is currently using TI's CC2540 for their tracker project and has encountered the following issues while scanning in master mode,

The customer's original question is as follows:

1.In our office environment (with over 100 Bluetooth devices around), I often encounter CCU being unable to scan and report beacon information within 15 seconds, 

even if the beacon pin is right next to the CCU.

In environments with high levels of Bluetooth, there may be situations where the target device cannot be scanned for a long time, and even if it is very close, it is often not scanned within 15 seconds.

The schematic diagram is as follows:

FF2768A3@D7E65D00.4D97FF6800000000.jpg

The test data is as follows:

 

 

 

 

 

 

 

 

 

 

 

ble scan ibeacon test data

Time taken to scan the target iBeacon

 

 

Version

scanning cycle

Scan Window

scan interval

0-1

1 - 2

2 - 3

>4

The longest time it takes to find the target iBeacon in a single search

The total number of times the target iBeacon has been scanned

Old version filtered broadcast

350ms

default

default

85609

8810

2098

824

14

97341

New version, unfiltered duplicate broadcasts

1000ms

500ms

500ms

163086

13302

1733

240

6

178361

2000ms

500ms

500ms

69408

7098

1204

379

8

78089

3000ms

500ms

500ms

45129

4158

774

210

15

50271

4000ms

500ms

500ms

45322

4077

540

101

6

50040

5000ms

500ms

500ms

8222

1022

518

4068

26

13730

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The percentage of testing times in each time period to the total testing times

 

 

Version

scanning cycle

Scan Window

scan interval

0-1

1 - 2

2 - 3

>4

 

 

Old version filtered broadcast

350ms

default

default

87.94%

9.05%

2.16%

0.84%

 

 

New version, unfiltered duplicate broadcasts

1000ms

500ms

500ms

91.43%

7.46%

0.97%

0.13%

 

 

2000ms

500ms

500ms

88.88%

9.09%

1.51%

0.49%

 

 

3000ms

500ms

500ms

89.77%

8.27%

1.54%

0.41%

 

 

4000ms

500ms

500ms

90.54%

8.18%

1.08%

0.20%

 

 

5000ms

500ms

500ms

59.88%

7.44%

3.77%

29.62%

 

 

 

  • 0
    TI__Genius 15965 points

    Hello Jimmy,

    Thanks for reaching out.

    In crowded BLE RF environments it is usual to see increased time to detect a specific device advertising. Do you have information about the beacon (broadcaster), what is the TX power, advertisement interval, etc?

    BR,

    David.

  • 0 in reply to David
    Genius 3585 points

    Hello David:

    1. The AD interval for the beacon pin is 500ms
    2. At present, the customer has provided a level and coverage area for Tx power, but specific parameters cannot be provided yet and are still being confirmed.

    Transmission power level

    In most scenarios, the transmission power can be selected as the default level 3.In special cases, it is necessary to appropriately scale the level of transmission power according to experience.For example, the parking range is relatively large, and it is acceptable for the vehicle to park in the scene of more than 4 times the area of the original parking area around the parking area. At this time, it can be considered to increase the transmission power level by 1 ~ 2 levels.

    Typical radius when set to different transmission power level:

    1-0.6m

    2-1.5m

    3-2m

    4-3m

    5-5m

     Note: The above is a typical value. In fact, which is not so accurate in practice.

  • 0 in reply to Jimmy Huang
    TI__Genius 15965 points

    Hello Jimmy,

    Some considerations:

    1. Slow advertising: higher advertising interval, lower power consumption, low probability of short discovery time
    2. Fast advertising: lower advertising interval, higher power consumption, high probability of short discovery time.
    3. In a time-constrained application, when the user needs to receive the data as fast as possible, make sure that scanning window is more than the advertising interval + 10ms to guarantee discovery. (The 10 ms extra account for the 0 ms to 10 ms of pseudo-random delay in between each advertising event, assuming no interference.)
    4. Directed Advertising: For rapid re-connection with a specific known device, use directed advertising, which can use low advertising intervals.
    5. Continuous Scanning: If you need to find devices continuously, you might set the scan duration to an indefinite value. Be aware that this may impact battery life.

    BR,

    David.