Configuring Transmit (Tx) power on the CYW20706

[Anonymous]

CYW20706 consists of a fully integrated Power Amplifier (PA) that supports Class 1 or Class 2 operation. The maximum possible Tx power is +12 dBm for BR/EDR applications and +9dBm for BLE applications. In WICED 5.2 and later, the wiced_bt_cfg_settings_t structure consists of a maximum power value, where you can specify the maximum transmit power in dBm necessary for your application.

The max Tx power can also be configured using the APIs mentioned below. Kindly note that the API definitions are not included in WICED. Nevertheless, these APIs can be used to modify the Tx power.

1. wiced_result_t wiced_bt_dev_set_adv_tx_power( int power );
   1. This API can be used to change the max Tx power for BLE advertisement. It changes the power to be used on the advertisement channels.
   2. Power should be a multiple of 4 from +8 dBm to -16 dBm, i.e. power can be +8, +4, 0, -4, -8, -12, -16 dBm.
   3. Example: wiced_bt_dev_set_adv_tx_power(-8);
2. wiced_result_t wiced_bt_dev_set_tx_power( wiced_bt_device_address_t bd_addr , int power );
   1. This API can be used to change the max Tx power for a BLE or BR/EDR connection. It changes the power to be used for the data channels for a specific connection.
   2. The first parameter should be the device address of the peer device.
   3. Power should be a multiple of 4 from +12 dBm to -16 dBm, i.e. power can be +12, +8, +4, 0, -4, -8, -12, -16 dBm.
   4. Example: wiced_bt_dev_set_tx_power(bd_addr,0);

[Anonymous]

Why do the comments for wiced_bt_cfg_settings_t say the max power setting is 10 dBm

    int8_t                              max_pwr_db_val;                 /**< Max. power level of the device ( Allowed range is from 0db to 10db)*/

} wiced_bt_cfg_settings_t;

[Anonymous]

I am working with a CYW20706 and WICED Studio 6.1 and am trying to control the TX power. The function wiced_bt_set_tx_power() doesn't seem to be available to me, when compiling the linker complains that the function is not found.

I have tried to set the TX power with max_pwr_db_val in wiced_bt_cfg_settings_t, but it does not seem to have any effect. I measure the current consumption of my board and it always stays the same. I have tried values from -20 to +8 with no effect on power consumption.

I got curious and tried a value of 100, which should not be allowed, but wiced_bt_stack_init() does return successfully, so I have the suspicion that the value of max_pwr_db_val is ignored by the stack.

Can you confirm that max_pwr_db_val can be used to set the TX power or tell another way to set the TX power on CYW20706 with WICED Studio 6.1?

[MichaelF_56]

Adding yssu​

Note that you may want to post these questions as new threads here: WICED Studio Bluetooth Forums​ since I'm not sure if the AE team is monitoring comments posted against documents.

[Anonymous]

Up until BT Spec 5.0, the max Tx power for BLE was +10dB. In 5.0, it was changed to +20dBm.

I guess the header file is not updated.

[Anonymous]

Answered here:

Configuring Transmit power on the CYW20706