configuring antenna properties

Thomas Keil

Intellectual 430 points

Other Parts Discussed in Thread: BLE-STACK, CC2640

Hello again,

I have a question about the antenna config. As described, there is a #define

#define RF_FE_MODE_AND_BIAS ( RF_FE_SINGLE_ENDED_RFP | RF_FE_INT_BIAS ) // RF_FE_DIFFERENTIAL

in the ICallBLE -> bleUserConfig.h

It seems for me this does not have an effect to our implementation. I cannot find out where this setting is used in the project or c files.

So, is this the right setting?

What is the meaning of this in bleUserConfig.c

// Differential Output
// ALT: Consider basing this direction on type of output (RF_FE_MODE_AND_BIAS)?

// Tx Power Values (Pout, IB, GC, TC)
const txPwrVal_t txPowerTable[] =
{ { TX_POWER_MINUS_21_DBM, GEN_TX_POWER_VAL( 0x07, 3, 0x0C ) },
{ TX_POWER_MINUS_18_DBM, GEN_TX_POWER_VAL( 0x09, 3, 0x0C ) },
{ TX_POWER_MINUS_15_DBM, GEN_TX_POWER_VAL( 0x0B, 3, 0x0C ) },
{ TX_POWER_MINUS_12_DBM, GEN_TX_POWER_VAL( 0x0B, 1, 0x14 ) },

We got a very poor communication range and very low (-75dB) level on a distance of 20cm.

Are there some hints?

over 9 years ago

0 JXS over 9 years ago

TI__Guru** 105180 points

Hello Thomas,

The defines that control this setting for CC2640 are in the respective board.h file. Also, although not stated, I'm assuming you are using BLE-Stack v2.1.x.

Can you post your schematic showing the antenna layout? I want to make sure you are using the right setting.

Best wishes

0 Fredrik K over 9 years ago

TI__Guru** 106705 points

Hi Thomas,

With such poor performance, it sounds like you have a HW problem. Have you gone through the HW design section on the BLE Wiki www.ti.com/ble-wiki ?

Cheers,
Fredrik

0 Thomas Keil over 9 years ago in reply to Fredrik K

Intellectual 430 points

0 Thomas Keil over 9 years ago in reply to Thomas Keil

Intellectual 430 points

Hallo Fredrik,
Yes, I assume a hardware / layout problem, but I also want to check if everything is set right in software.
We use BLE stack 2.1 and the antenna dedign is shown above.
One question is open: where in the software the setting of RF_FE_MODE_AND_BIAS is written to the controler? I adjust this macro to RF_FE_SINGLE_ENDED_RFP | RF_FE_INT_BIAS but whatever I select here, it has no effect to radio strength.

Thanks very much for Your help.

0 Fredrik K over 9 years ago in reply to Thomas Keil

TI__Guru** 106705 points

Hi Thomas,

How do you measure the RF performance?

You are using external biasing btw.

Cheers,
Fredrik

0 Thomas Keil over 9 years ago in reply to Fredrik K

Intellectual 430 points

Hallo Fredric,

I measured with the smartRF packet sniffer, shows the RSSI level.
in bleUserConfig.h is set: #define RF_FE_MODE_AND_BIAS ( RF_FE_SINGLE_ENDED_RFP | RF_FE_INT_BIAS )
This should be internal bias but I dont know if this is OK.

The applicasion is based on the simpleBLEPeriphal example from TI. I rely on all the initializations made by TI and I only change the port init in board.h.
Must I add some code to set the antenna config and where?

Thanks,
Thomas

0 Fredrik K over 9 years ago in reply to Thomas Keil

TI__Guru** 106705 points

Hi Thomas,

Can you post the layout of your RF circuitry?

Cheers,

Fredrik

0 Klaus Nikolaus over 9 years ago in reply to Fredrik K

Prodigy 50 points

Hi Fredrik,

this is the PCB Design:

The PCB has a round shape and the SMD Chip Antenna is placed on the left side.

There is no copper in the area of the chip antenna on any layer.

Regards,

Klaus

0 Fredrik K over 9 years ago in reply to Klaus Nikolaus

TI__Guru** 106705 points

Hi Klaus,

The layout looks ok. Have you measured the conducted output power?

Cheers,
Fredrik

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configuring antenna properties