STM32F765 - CC2564B RF Power Configurations

[yavuz kağan topak]

Hi Matthias,

I have tested CC2564B chip with STM32f765 processor with your btstack. As I said before SPP and GAP profile were run in a good way. 

Now, I am investigating RF power control of CC2564B chip. I have written some HCIcommands which are written into this link "http://processors.wiki.ti.com/index.php/CC256x_VS_HCI_Commands" . HCI commands that I am using listed the following and

use this sequence:

 1) HCI_VS_DRPb_Set_Power_Vector (0xFD82)

    uint8_t hci_cmd_power_vector_buffer[24] = 

    {

        0x01, 0x82, 0xfd, 0x14, 0x00, 0x9c, 0x18, 0xd2, 0xd2, 0xd2, 0xd2, 0xd2, 0xd2, 0xd2, 0xdc,

        0xe6, 0xf0, 0xfa, 0x04, 0x0e, 0x18, 0xff, 0x00, 0x00,

    };

2) HCI_VS_DRPb_Set_Class2_Single_Power (0xFD87)

    uint8_t hci_cmd_set_class2_single_power[7] = 

    {

        0x01, 0x87, 0xFD, 0x03, 0x0F, 0x0F, 0x0F        

    };

3) HCI_VS_DRPb_Enable_RF_Calibration (0xFD80)

   uint8_t hci_cmd_rf_calibration[10] =

    {

       0x01, 0x80, 0xFD, 0x06, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x01

    };

After these commands, in order to measure output RF power I have sent

4) HCI_VS_DRPb_Tester_Con_TX(0xFD84)

 uint8_t hci_cmd_cont_tx[16] = 

    {

       0x01, 0x84, 0xFD, 0x0C, 0x01, 0x04, 0x18, 0x0F... reserved 8byte 

    }; 

  

  Above command means that:

  modulation type: GFSK

  test pattern        : All 0

  Frequency         : 2.450 GHz

  Power Level      : 15

According to RF Power measurement result, in the continuous TX process CC2564B chip gives power about  8 dBm

But, Normally, after the  Set Power Vector commands, chip must give 12 dBm power if Power Level is equal to 15.

I have read your submit in the TI community:

https://e2e.ti.com/support/wireless_connectivity/bluetooth_cc256x/f/660/t/134853?Output-power-configuration-of-CC256x

Is there any limit of the RF power of CC2564B chip in the BTStack configurations ?

Why I cannot measure the 12 dBm power even if Power Level 15 ?

What is the default power class of BTStack for CC2564B chip?

Can I change the power class number of the CC2564B with help of BTStack ?

 

[Matthias Ringwald]

Hi Yavuz

You can set/limit the power by calling

/** 

 * Configure output power before HCI POWER_ON

 */

void btstack_chipset_cc256x_set_power(int16_t power_in_dB);

The default in btstack_chipset_cc256x.c is 13 btw.

The code then uses this to calculate the different levels following the TI recommendations. I've never measured it myself, but others did use this call to reduce the power level and get their devices tested/certified. I'm happy if I can communicate with other devices :) I'm not familiar with the RF part. Maybe you can ask in TI's forum?

What do you want to achieve? 

Best

  Matthias

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[yavuz kağan topak]

Hi,

Thanks for fast answering. I am a master student and investigate CC2564B chip for term project. For this reason, I have to measure RF power characteristic

of the bluetooth chip. I have control your code according to your answer, after a few measurements and experiment maximum output power of the chip is 6,98 dBm instead of 12 dBm.

I don't understand why the therotical measurement results and practical case are not match... I cannot answer this question yet :( 

Does your BTStack algorithm load the init script file every opening process and configure the chip in accordance with init script file?

Do I understand that correctly?

Best 

Yavuz

17 Mayıs 2018 Perşembe 19:23:01 UTC+3 tarihinde Matthias Ringwald yazdı:

[Matthias Ringwald]

Hi Yavuz

Ok, I see why you want full control for your measurements. I would suggest to post on TI's E2E forum, they have been very helpful in the past. 

I don't know much about analog RF stuff. How do you measure the dBm value? Do you put some probe directly at the chip's antenna pin?

BTstack loads the init script on each start. However, it assumes that there is none, so you (manually) have to reset the cc256x before start. in embedded systems, the cc256x n_shutdown line is connected to the MCU, so it is usually reset as part of power up by the MCU.

Best

 Matthias