6.6. BLE Coexistence with other 2.4GHz radios

The aim of this chapter is to describe the main steps to enable WLAN coexistence support for the DA1453x/DA1458x.

6.6.1. Introduction

../_images/wlan_coex_setup.png — Figure 92 **WLAN coexistence with BLE**

The WLAN coexistence feature on DA1453x/DA1458x is designed to allow multiple 2.4 GHz devices to operate without signals from one radio interfering with adjacent radios. This is done by a handshaking protocol between the BLE device and the other 2.4 GHz device using the following signals:

WLAN_COEX_BLE_EIP signal: The DA1453x/DA1458x can communicate its radio status in advance using the abovementioned signal. WLAN_COEX_BLE_EIP is an envelop of the scheduled TX and RX radio activity of the BLE Radio and it starts before the actual radio activity so it can upfront inform the coexisting system of scheduled RF activity. The signal is de-asserted synchronously directly after radio activity is finished.

WLAN_COEX_BLE_PRIO signal

The DA1453x/DA1458x can enable a priority line to indicate that it can not be interrupted for a defined activity. The activity for which BLE needs priority can be defined through the API.

The WLAN_COEX_BLE_PRIO signal is controlled internally by the DA1453x/DA1458x firmware, following certain user configurable rules. In the following table are listed all available priorities.

Table 109 The commands to configure the priorities for the WLAN coexistence feature
Rule	Command	Priority Type
1	wlan_coex_prio_criteria_add(BLEMPRIO_SCAN, LLD_ADV_HDL, 0);	Active scan
2	wlan_coex_prio_criteria_add(BLEMPRIO_ADV, LLD_ADV_HDL, 0);	Advertise
3	wlan_coex_prio_criteria_add(BLEMPRIO_CONREQ, LLD_ADV_HDL, 0);	Connection request
4	wlan_coex_prio_criteria_add(BLEMPRIO_LLCP, 0, 0);	Control packet
5	wlan_coex_prio_criteria_add(BLEMPRIO_DATA, 0, 0);	Data packet
6	wlan_coex_prio_criteria_add(BLEMPRIO_MISSED, 0, 4);	Missed events (in this example, after 4 bad packets)

WLAN_COEX_24G_EIP signal: Input signal to DA1453x/DA1458x device. External 2.4GHz device event in progress indication.

Note

Detailed information about WLAN Coexistence driver can be found in API documentation.

6.6.2. Enabling WLAN Coexistence feature

As an example, we will proceed to outline how WLAN coexistence feature could be enabled in prox_reporter_ext project:

As an example, in da1458x_config_advanced.h, use the following preprocessor definitions in order to enable WLAN coexistence mode with or without debugging signals and set the preferred polarity of the BLE event in progress signal:

/****************************************************************************************************************/
/* WLAN coexistence mode: Enable/disable the mode.                                                              */
/****************************************************************************************************************/
#define CFG_COEX

/****************************************************************************************************************/
/*  WLAN coexistence mode: Enable/disable the debugging signals.                                                */
/****************************************************************************************************************/
#define CFG_WLAN_COEX_DEBUG

/****************************************************************************************************************/
/* WLAN coexistence mode: Controls the polarity of the BLE event in progress signal.                            */
/* - defined: BLE event in progress signal is active low.                                                       */
/* - undefined: BLE event in progress signal is active high.                                                    */
/****************************************************************************************************************/
#undef CFG_WLAN_COEX_BLE_EVENT_INV

The following source file must be added to the project:
- wlan_coex.c comprise the WLAN coexistence feature implementation and reside in <sdk_root_directory>\sdk\platform\driver\wifi. The files can easily be added by right click on the corresponding folder and select the Add Existing files to Group… option.
The following include path must be added to the project. Click on the Options for Target… and then in the C/C++ tab. In the include Paths field add the wifi folder that holds the wlan_coex.h file.

../_images/wlan_coex_include_path.png — Figure 93 **WLAN COEX include path**

In user_periph_setup.h the following block of definitions should be added for WLAN coexistence pin mapping:

/****************************************************************************************/
/* WLAN COEX pin configuration                                                          */
/****************************************************************************************/

#if (WLAN_COEX_ENABLED)
#if defined (__DA14531__)

   /// Input signal to device: 2.4GHz external device event in progress indication.
   #define WLAN_COEX_24G_EIP_PORT      GPIO_PORT_0
   #define WLAN_COEX_24G_EIP_PIN       GPIO_PIN_5

   /// Output signal from device: BLE event in progress indication.
 #define WLAN_COEX_BLE_EIP_PORT      GPIO_PORT_0
 #define WLAN_COEX_BLE_EIP_PIN       GPIO_PIN_6

   /// Output signal from device: BLE priority indication.
   #define WLAN_COEX_BLE_PRIO_PORT     GPIO_PORT_0
   #define WLAN_COEX_BLE_PRIO_PIN      GPIO_PIN_7

#if defined (CFG_WLAN_COEX_DEBUG)
   /// BLE radio overruled signal pin definition.
   /// This signal goes high when the BLE radio is forced to be off due to external 2.4GHz device activity.
   #define WLAN_COEX_DEBUG_A_PORT      GPIO_PORT_0
   #define WLAN_COEX_DEBUG_A_PIN       GPIO_PIN_9

   /// External 2.4GHz device EIP handler signal pin definition.
   /// This signal indicates when an external 2.4GHz device wants to start or stop sending data.
   #define WLAN_COEX_DEBUG_B_PORT      GPIO_PORT_0
   #define WLAN_COEX_DEBUG_B_PIN       GPIO_PIN_8
#endif

#else

   /// Input signal to device: 2.4GHz external device event in progress indication.
   #define WLAN_COEX_24G_EIP_PORT      GPIO_PORT_0
   #define WLAN_COEX_24G_EIP_PIN       GPIO_PIN_0

   /// Output signal from device: BLE event in progress indication.
   #define WLAN_COEX_BLE_EIP_PORT      GPIO_PORT_0
   #define WLAN_COEX_BLE_EIP_PIN       GPIO_PIN_3

   /// Output signal from device: BLE priority indication.
   #define WLAN_COEX_BLE_PRIO_PORT     GPIO_PORT_0
   #define WLAN_COEX_BLE_PRIO_PIN      GPIO_PIN_2

#if defined (CFG_WLAN_COEX_DEBUG)
   /// BLE radio overruled signal pin definition.
   //  This signal goes high when the BLE radio is forced to be off due to external 2.4GHz device activity.
   #define WLAN_COEX_DEBUG_A_PORT      GPIO_PORT_0
   #define WLAN_COEX_DEBUG_A_PIN       GPIO_PIN_1

   /// External 2.4GHz device EIP handler signal pin definition.
   /// This signal indicates when an external 2.4GHz device wants to start or stop sending data.
   #define WLAN_COEX_DEBUG_B_PORT      GPIO_PORT_1
   #define WLAN_COEX_DEBUG_B_PIN       GPIO_PIN_3
#endif

#endif

// GPIO IRQ number. Interrupt is fired when 2.4GHz external device event in progress signal is activated.
#define WLAN_COEX_IRQ            4

#endif // WLAN_COEX_ENABLED

In user_periph_setup.c make the following changes in order to enable properly WLAN coexistence feature:
Add the required include file. Include wlan_coex.h in the Include Files section.

#if (WLAN_COEX_ENABLED)
#include "wlan_coex.h"
#endif

Add the following global variable definition (configuration struct for WLAN coexistence):

#if (WLAN_COEX_ENABLED)
// Configuration struct for WLAN coexistence
const wlan_coex_cfg_t wlan_coex_cfg = {
   .ext_24g_eip_port = WLAN_COEX_24G_EIP_PORT,
   .ext_24g_eip_pin = WLAN_COEX_24G_EIP_PIN,
   .ble_eip_port = WLAN_COEX_BLE_EIP_PORT,
   .ble_eip_pin = WLAN_COEX_BLE_EIP_PIN,
   .ble_prio_port = WLAN_COEX_BLE_PRIO_PORT,
   .ble_prio_pin = WLAN_COEX_BLE_PRIO_PIN,
#if defined (CFG_WLAN_COEX_DEBUG)
   .debug_a_port = WLAN_COEX_DEBUG_A_PORT,
   .debug_a_pin = WLAN_COEX_DEBUG_A_PIN,
   .debug_b_port = WLAN_COEX_DEBUG_B_PORT,
   .debug_b_pin = WLAN_COEX_DEBUG_B_PIN,
#endif
   .irq = WLAN_COEX_IRQ,
};
#endif

Reserve GPIOs used by the module by adding the following block of code inside GPIO_reservations() function:

#if (WLAN_COEX_ENABLED)
   RESERVE_GPIO(COEX_EIP, wlan_coex_cfg.ble_eip_port, wlan_coex_cfg.ble_eip_pin, PID_GPIO);
   RESERVE_GPIO(COEX_PRIO, wlan_coex_cfg.ble_prio_port, wlan_coex_cfg.ble_prio_pin, PID_GPIO);
   RESERVE_GPIO(COEX_REQ, wlan_coex_cfg.ext_24g_eip_port, wlan_coex_cfg.ext_24g_eip_pin, PID_GPIO);

#if defined (CFG_WLAN_COEX_DEBUG)
   RESERVE_GPIO(DEBUGPIN1, wlan_coex_cfg.debug_b_port, wlan_coex_cfg.debug_b_pin, PID_GPIO);
   RESERVE_GPIO(DEBUGPIN2, wlan_coex_cfg.debug_a_port, wlan_coex_cfg.debug_a_pin, PID_GPIO);
#endif

../_images/changes_in_GPIO_reservations_function.png — Figure 94 **Changes in GPIO_reservations() function**

Call wlan_coex_gpio_cfg() function at the end of set_pad_functions() to initialize GPIOs used by the module and to configure 2.4GHz external device event in progress signal to act as a GPIO interrupt.

#if (WLAN_COEX_ENABLED)
   wlan_coex_gpio_cfg();
#endif

../_images/changes_in_set_pad_functions.png — Figure 95 **Changes in set_pad_functions()**

Last but not least, it should be mentioned that the following changes are required in user_proxr.c in order to initialize the WLAN-BLE coexistence mode and set the BLE priority over the WLAN module.
Add the required include files. Include wlan_coex.h and lld.h in the Include Files section.

#if (WLAN_COEX_ENABLED)
#include "wlan_coex.h"
#include "lld.h"
#endif

Call inside user_on_init() the following functions:
- wlan_coex_init() in order to initialize the WLAN-BLE coexistence mode;
- wlan_coex_prio_criteria_add() function to configure the rules for the WLAN coexistence feature.

#if (WLAN_COEX_ENABLED)
   wlan_coex_init();

   // Adds priority case for a specific connection
   wlan_coex_prio_criteria_add(WLAN_COEX_BLE_PRIO_ADV, LLD_ADV_HDL, 0);
#endif

Finally call wlan_coex_going_to_sleep() function inside user_validate_sleep() in order to prepare WLAN COEX mode for going to sleep.

#if (WLAN_COEX_ENABLED)
   wlan_coex_going_to_sleep();
#endif

../_images/changes_in_user_proxr_file.png — Figure 96 **Changes in user_proxr.c file**