Transmit power BLE 88w8987

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Transmit power BLE 88w8987

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ac_gd
Contributor I

Hi,

We use the 1ZM M.2 Module of Embedded Artists which includes the NXP 88w8987 chipset, connected to the iMX6ULL evaluation kit.

We have 2 questions regarding the transmit power of the 88w8987 chipset for Bluetooth Low Energy:

  • Is it correct that the max. BLE transmit power 10 dBm (for both BLE 1M and 2M PHYs)? We found this value in this datasheet.
  • How do we change the transmit power for BLE of the 88w8987? More specifically:
    • Does `hciconfig hci0 inqtpl [x]` have any effect on the transmit power?
      • By default the output power seems to be 3 dBm.
      • The max. I can set seems to be 12 dBm, which is higher than the 10 dBm found in the datasheet. So I wonder if this command correctly gets/set the transmit power?
    • Is there a vendor specific `hcitool cmd xxxx xxxx ...` we should use to set the transmit power?

 

root@00049F06F57F:~# hciconfig hci0 inqtpl
hci0:   Type: Primary  Bus: UART
        BD Address: D4:53:83:C3:DE:BB  ACL MTU: 1016:5  SCO MTU: 60:12
        Inquiry transmit power level: 12
​

 

Kind regards,
ac_gd

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3 Replies

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nxf77486
NXP Employee
NXP Employee

Hello @ac_gd ,

Thank you in advance for contacting NXP community support. Regarding g your questions:

  1. The BLE transmit power in this case will have to be consulted to your product manufacturer, because this could have variations.
  2. To change the transmit power for the BLE, we have the following user maual , in the section 3.8.7 Set Tx power you will find the command to set the Tx power. Please let me know if this information in case this is not what you are looking for let me know so we can find a solution.
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ac_gd
Contributor I

Hi,

Thank you for your answer.

  1. Ok, I will contact Murata to ask about the max TX power.
  2. Concerning the HCI command for setting the BLE TX power:
    1. If I set it to the max value "Maximum value = 0x14 (20 dBm)" (hcitool -i hci0 cmd 0x3F 0x87 0x14), but the module only allows up to 10 dBM, am I correct to assume that it will automatically set it to the module's max, i.e., 10 dBm?
    2. Is there also a command to read - instead of write - the configured TX power?

Thanks in advance.

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nxf77486
NXP Employee
NXP Employee

 

Spoiler
 

Hello,

 

I apologize in advance for the late response.

Regarding your question I have the following recommendations:

  1. Reset the values to the normal standard ones, before modifying them. As it was told previously this values could change depending on the manufacturer.
  2. The commands available for the HCI are only the ones included in the guide previously send.

Please let me know if you have any other question, we will be glad to assist you.

 

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