How to Use XT/XR Modules without making use of the Power Amplifier (Normal BLE Module)?
In existing BLE XT/XR Modules, if the PA/LNA is not enabled, ideally, there would be no radiations, but practically, there would be some leakage radiations. In this case, the range would be somewhere around a few centimeters. Sometimes, it might be necessary to use these modules for shorter range and/or might require them to operate at lower power.
The steps to enable the extended range functionality is available in the datasheets of these modules and also in the AN96841 - Getting Started With EZ-BLE™ Module application note. An important step in this procedure is including the lines given below under CYBLE_EVT_STACK_ON. By writing '1' to both CSD and CPS pins, the PA is enabled and the increased gain can be obtained.
/* Configure the Link Layer to automatically switch PA control pin P3 and LNA control pin P3 */
CY_SET_XTND_REG32 ((void CYFAR *)(CYREG_BLE_BLESS_RF_CONFIG), 0x0331);
CY_SET_XTND_REG32 ((void CYFAR *)(0x40030008), 0x80000302);
If these modules must be used as a non-XT module, it can be done by putting the PA/LNA in bypass mode. To do so, just write a '1' to the CSD pin and a '0' to the CPS pin; i.e.,
This puts the PA/LNA in bypass mode and the output Tx power will be as set by you either in the BLE Component configuration or in the firmware (+3 dBm to -18 dBm). In the bypass mode, the PA/LNA module will not add any gain. This information about the bypass mode can be obtained from the datasheet of the Skyworks SE2438T module.