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WICED Smart Bluetooth

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I have a couple of question regarding the maximum paring distance possible.

Please discuss the follow basic questions below.

1) Is there a way to increase paring distance by optimizing hello_sensor code, regardless of Hardware?

   I have implemented a routine that sets up the Tx power as 4dBm using the "blecm_setTxPowerInADV( )" on "hello_sensor_create( )"

   In addition to setting the parameter, CONST definition of the BLE_PROFILE_CFG in hello_sensor application,

   I wonder if there is any way to increase the paring distance or to stabilize the paring sequence on that application.


2) The pairing distance possible varies with commercially available mobile OS type and applications.

   What is major factor affecting the paring distance without hardware components such as build in antenna.

   If you are a specialist in that part of BLE software, could you send us information about it?

* Development Environment


-Development tool: WICED-Smart SDK2.2.3 IDE



3 Replies

4 dBm of Tx power is the max we can go within the class 2 requirement. In actual deployment, I wouldn't go beyond 10m for reliable connection, considering antenna efficiency as well as orientation.

BT has something known as RSSI. Essentially, if two devices are near to each other, they will reduce their required Tx power to talk to each other. And vice versa.

What is the range you are looking for? Bearing in mind that BT/BLE are PAN devices which are never intended for "long" range use. If you really want range, then you might want to consider using BT instead of BLE. The former can be configured as a Class 1 (up to 20dBm of Tx power) and will definitely have a much better range.

Not applicable

Thank you in advance for your reply.

I want "20737S" to have reliable paring performance within 10 meters.

Our requirement is that It should be able to have reliable connection between mobile application and our device.

But the our product device is wrapping aluminum cover or some kind of stainless steel case.

That is just the problem. RSSI value is getting quite weak because of the enclosure case.

I test the pairing distance within 10 meters with that case opened. Nevertheless, I can not

scan the device on the mobile application occasionally. The pairing distance varies with commercially

available mobile phone or some BLE scanner apps.

I don't know what factors affect the reliable connection and the paring distance.

That is why I asked the question on the previous post. I just want reliable paring and stable connection within

available range.


The metallic shielding could potentially have some negating effect on the RF radiation. I advise you seek out your HW engineers to come out with an optimum placement of the 20737S within your product.

You may want to use "LightBlue", an app available on iOS, to discover the module and take note of the received signal strength at say 5m, 8m and 10m. If you see something below -90dB, then you are nearing the limit already. In my opinion, I think -80dB is probably the weakest signal if you want to maintain some reliability...