Persistent Pairing data and keys examples?

[tbandtg]

When I use the sdk to create an example none of them seem to store pairing data and keys in flash. I have searched for a good example and nothing really seems to work. Pairing and connections work the first time but are lost on reset. You would think there would be thousands of these.

Is there an example out there that shows the PICO W as a ble device that can

1. Pair and connect
2. ON reset reconnect to that same host
3. Delete pairing so that a new host can be used.

I am including where I am there is some commented code because I thought I would have to implement a tlv but that didnt help.

**
 * @brief Function to initialize the BLE driver
 * @returns sErrorStruct_t structure with error code and line number.
 */
sErrorStruct_t initializeBLE(void)
{
    sErrorStruct_t retValue = BLANK_ERROR_STRUCT;
    uint16_t adv_int_min = 0x0030;
    uint16_t adv_int_max = 0x0030;
    uint8_t adv_type = 0;
    bd_addr_t null_addr;
    //retValue = initializeBLEStorage();

    bool bondedDevice = hasBondingData();
    if(ERROR_NONE == retValue.errorCode)
    {

        DEBUG_PRINT("BLE bonding data %s\n", bondedDevice ? "exists" : "does not exist");
        btstack_memory_init();        


        // register for HCI events
        HCIEventCallbackRegistration.callback = (btstack_packet_handler_t)(&packetHandler);
        hci_add_event_handler(&HCIEventCallbackRegistration);

        // register for SM events
        SMEventCallbackRegistration.callback = (btstack_packet_handler_t)(&smEventHandler);
        sm_add_event_handler(&SMEventCallbackRegistration);
        btstack_tlv_get_instance(&tlv, &tlv_ctx);
        if (tlv && tlv_ctx){
            // Tell LE device DB (bond store) to use TLV in flash
            le_device_db_tlv_configure(tlv, tlv_ctx);
        } else {
            // Fallback (RAM only) — not persistent
            DEBUG_PRINT("WARNING: No TLV backend available; bonding will NOT persist!\n");
        }   
        // Initialize LE Device Database for bonding
        //le_device_db_tlv_configure(ble_tlv_get_instance(), NULL);

        // l2cap inititialization
        l2cap_init();
        // Secuurity manager initialization
        sm_init();

        sm_set_io_capabilities(IO_CAPABILITY_NO_INPUT_NO_OUTPUT);


        sm_set_authentication_requirements(AUTH_REQ);
        sm_set_encryption_key_size_range(MIN_ENC_KEY_SIZE, MAX_ENC_KEY_SIZE);
        sm_set_request_security(1);                    // request encryption on connection if possible
        sm_set_accepted_stk_generation_methods( SM_STK_GENERATION_METHOD_JUST_WORKS
                                            |SM_STK_GENERATION_METHOD_PASSKEY ); // adjust as needed
        // setup ATT server
        att_server_init(profile_data, NULL, NULL);

        // setup battery service
        battery_service_server_init(batteryPercentage);

        // setup device information service
        device_information_service_server_init();

        // setup HID Device service
        hids_device_init(0, hid_descriptor_keyboard_boot_mode, sizeof(hid_descriptor_keyboard_boot_mode));

        // setup advertisements
        memset(null_addr, 0, 6);

        gap_advertisements_set_params(adv_int_min, adv_int_max, adv_type, 0, null_addr, 0x07, 0x00);
        
        gap_advertisements_set_data(advertisementDataLength, (uint8_t*) advertisementData);

        setBLEAdvertising(true);

        // Initialize the queue for HID keyboard reports
        queue_init_with_spinlock(&hidKeyboardReportQueue, sizeof(hid_keyboard_report_t), REPORTS_IN_QUEUE, spin_lock_claim_unused(true)); // 10 reports in the queue
        // turn on!
        hci_power_control(HCI_POWER_ON);
    }

    return retValue;
}

[peterharperuk]

le_device_db_tlv_configure is called for you. The hid_mouse example seems to work for me when connecting to windows.

[tbandtg]

I tried the HID Mouse demo as written and it hardfaults out the gate. Is there an updated one or one that works with the pico sdk.

It is not one of the ones you can just select from the menu and it hard faults at

/**
 * btstack_linked_list_add
 */
bool btstack_linked_list_add(btstack_linked_list_t * list, btstack_linked_item_t *item){        // <-- add item to list
    // check if already in list
    btstack_linked_item_t *it;
    for (it = *list; it != NULL; it = it->next){
        if (it == item) {
            return false;
        }
    }
    // add first
    item->next = *list;
    *list = item;
    return true;
}

[tbandtg]

Did you have a full project with that demo working.

[peterharperuk]

Did you have a full project with that demo working.

I literally ran it yesterday. Can you give me the callstack when it crashes?

[lurch]

Does "It is not one of the ones you can just select from the menu" mean that you're using the Pico VSCode extension?

[shermp]

I've found bonding to basically be automatic in btstack. A couple of things I can maybe think of:

1. Have you set SM_AUTHREQ_BONDING (along with any other flags) in sm_set_authentication_requirements()?
2. Check that flash is not blocked from writing - see pico_flash. For example, if using multi-core, you would need to set flash_safe_execute_core_init() on the other core.

[matsobdev]

For example no_flash binary with SDK 2.2.0 works with Pico W, but it won't bond even with SM_AUTHREQ_BONDING. What type of binary do you use?

[shermp]

I've used both a standard and copy_to_ram build, both work. My project is using multi-core, so I had to set flash_safe_execute_core_init().

My project is Pico-ASHA, but I don't know how useful it will be as an example.

[tbandtg]

Does "It is not one of the ones you can just select from the menu" mean that you're using the Pico VSCode extension?

Yes, so I set up a blank project and included the pico bt_stack_config.h included with the sdk. And then copied the .c file over for the hid_mouse_demo.c from sdk/lib/btstack/example I then ran that btstack_main. No changes or deviations from the example were made as I wanted to only see it store and reuse pairing data across a hw reset.

Add any user requested libraries

target_link_libraries(mouseDemo
pico_time
pico_btstack_ble
pico_btstack_classic
pico_btstack_cyw43
pico_btstack_flash_bank
pico_stdlib
pico_platform
pico_cyw43_arch_lwip_threadsafe_background
)

int main()
{
stdio_init_all();
btstack_main(0, NULL);
}

call stack

isr_hardfault@0x1000011c (c:\Users\agarza.pico-sdk\sdk\2.2.0\src\rp2_common\pico_crt0\crt0.S:333)
@0xfffffff9 (Unknown Source:0)
btstack_linked_list_add_tail@0x1000a6c8 (c:\Users\agarza.pico-sdk\sdk\2.2.0\lib\btstack\src\btstack_linked_list.c:93)
hci_add_event_handler@0x1000c03a (c:\Users\agarza.pico-sdk\sdk\2.2.0\lib\btstack\src\hci.c:4841)
l2cap_init@0x10010386 (c:\Users\agarza.pico-sdk\sdk\2.2.0\lib\btstack\src\l2cap.c:979)
btstack_main@0x10000470 (c:\Work\picoHandScanner\testbletwo\PicoMouseTest\hid_mouse_demo.c:300)
main@0x10000242 (c:\Work\picoHandScanner\testbletwo\PicoMouseTest\PicoMouseTest.c:10)

btstack_config.txt

[tbandtg]

Needed this

cyw43_arch_init();

which I put in there and ran the demo.

Pairs but does not reconnect over a reset.

This example like all of the others does not properly store pairing keys and information in flash.

[tbandtg]

I finally got this to work, between the above project and where I had been churning for so long. You can close this issue if you would like.

Needed to adjust the linker file to ensure that nothing was going in the last 64k of flash. Included my init. Would be great if one of the pull down menu examples implemented the flash tlv and explained all of this. Anyway in case someone comes after me and finds similar issues here is where it wored for me.

Here is from my linker
`
/* Linker script for RP2350 with 16kb Flash reserved for NVMM and 64kb reserved for BLE*/

__XIP_BASE      = 0x10000000;
__XIP_TOTAL     = 0x00400000;      /* 4MB total Flash */
__NVMM_SIZE     = 0x000004000;      /* 16k reserved at end */
__BLE_SIZE      = 0x000010000;      /* 64k reserved at end */
__XIP_SIZE      = __XIP_TOTAL - __NVMM_SIZE - __BLE_SIZE; /* 0x3ea000 usable Flash */
__NVMM_BASE     = __XIP_BASE  + __XIP_SIZE;
__BLE_BASE      = __NVMM_BASE + __NVMM_SIZE;
__SRAM_BASE     = 0x20000000;
__SRAM_TOTAL    = 0x80000;        /* 512 KB */
__SRAM_SCRATCH_SIZE = 0x4000;     /* Scratch used for each stack 16KB */
__NOINIT_SIZE   = 0x800;          /* 1KB persistent .noinit RAM */
__SRAM_SIZE     = __SRAM_TOTAL - __SRAM_SCRATCH_SIZE - __SRAM_SCRATCH_SIZE - __NOINIT_SIZE;
__NOINIT_BASE = __SRAM_BASE + __SRAM_SIZE;
__SCRATCH_X_BASE = __NOINIT_BASE + __NOINIT_SIZE;
__SCRATCH_Y_BASE = __SCRATCH_X_BASE + __SRAM_SCRATCH_SIZE;


/* Add NVMM section in flash, before .btstack_tlv_data */
.nvmm (NOLOAD) :
{
	. = ALIGN(4);
	__nvmm_start__ = .;
	*(.nvmm)
	FILL(0xFF)
    . = __nvmm_start__ + 0x000004000; /* 0x4000 = 16KB */
	__nvmm_end__ = .;
} > NVMM

/* Add BLE persistent TLV section in flash */
.btstack_tlv_data (NOLOAD) : 
{
    __btstack_tlv_start = .;
    FILL(0xFF)
    . = __btstack_tlv_start + 0x000010000; /* 0x000010000 = 64k */
    __btstack_tlv_end__ = .;
} > BLE

'
'

#include <stdio.h>
#include "pico/stdlib.h"
#include "hardware/regs/addressmap.h"
#include "pico/cyw43_arch.h"
#include "pico/util/queue.h"
#include "bleDriver.h"
#include <stdint.h>
#include <string.h>
#include <inttypes.h>
#include "btstack_config.h"
#include "hardware/flash.h"
/** Generated File */
#include "hid_keyboard.h"

#include "btstack.h"
#include "btstack_tlv.h"
#include "hci.h"
#include "btstack_tlv_flash_bank.h"
#include "ble/gatt-service/battery_service_server.h"
#include "ble/gatt-service/device_information_service_server.h"
#include "ble/gatt-service/hids_device.h"
#include "btstack_run_loop.h"

#include "ble/sm.h"
#include "errorCodes.h"
#include "errorDriver.h"
#include "appconfig.h"
#include "pico/util/queue.h"
#include "gap.h"
#include "l2cap.h"
#include "ble/le_device_db.h"
#include "ble/le_device_db_tlv.h"
#include "btstack_debug.h"
#include "hci_dump.h"
#include "hci_dump_embedded_stdout.h"   // for Pico/embedded
#include "hardware/regs/addressmap.h"   // XIP_BASE

 /**
 * @brief Function to initialize the BLE driver
 * @returns sErrorStruct_t structure with error code and line number.
 */
sErrorStruct_t initializeBLE(void)
{
    sErrorStruct_t retValue = BLANK_ERROR_STRUCT;
    uint16_t adv_int_min = 0x0030;
    uint16_t adv_int_max = 0x0030;
    uint8_t adv_type = 0;
    bd_addr_t null_addr;


    // Send HCI dump + logs to stdout (USB CDC/UART depending on your stdio)
    hci_dump_init(hci_dump_embedded_stdout_get_instance());
    hci_dump_enable_packet_log(true);
    // Optional: prove it’s live
    log_info("BTstack logging enabled");

    
    btstack_memory_init();  


    // register for HCI events
    HCIEventCallbackRegistration.callback = (btstack_packet_handler_t)(&packetHandler);
    hci_add_event_handler(&HCIEventCallbackRegistration);

    // register for SM events
    SMEventCallbackRegistration.callback = (btstack_packet_handler_t)(&smEventHandler);
    sm_add_event_handler(&SMEventCallbackRegistration);
    btstack_tlv_get_instance(&tlv, &tlv_ctx);
    if (tlv && tlv_ctx){
        // Tell LE device DB (bond store) to use TLV in flash
        le_device_db_tlv_configure(tlv, tlv_ctx);
    } else {
        // Fallback (RAM only) — not persistent
        DEBUG_PRINT("WARNING: No TLV backend available; bonding will NOT persist!\n");
    }
    bool bondedDevice = hasBondingData();
    DEBUG_PRINT("BLE bonding data %s\n", bondedDevice ? "exists" : "does not exist");
    // l2cap inititialization
    l2cap_init();
    // Secuurity manager initialization
    sm_init();

    sm_set_io_capabilities(IO_CAPABILITY_NO_INPUT_NO_OUTPUT);

    bondedDevice = hasBondingData();
    DEBUG_PRINT("BLE bonding data %s\n", bondedDevice ? "exists" : "does not exist");
    sm_set_authentication_requirements(AUTH_REQ);

    // setup ATT server
    att_server_init(profile_data, NULL, NULL);

    // setup battery service
    battery_service_server_init(batteryPercentage);

    // setup device information service
    device_information_service_server_init();

    // setup HID Device service
    hids_device_init(0, hid_descriptor_keyboard_boot_mode, sizeof(hid_descriptor_keyboard_boot_mode));

    // setup advertisements
    memset(null_addr, 0, 6);

    gap_advertisements_set_params(adv_int_min, adv_int_max, adv_type, 0, null_addr, 0x07, 0x00);
    
    gap_advertisements_set_data(advertisementDataLength, (uint8_t*) advertisementData);

    setBLEAdvertising(true);

    // Initialize the queue for HID keyboard reports
    queue_init_with_spinlock(&hidKeyboardReportQueue, sizeof(hid_keyboard_report_t), REPORTS_IN_QUEUE, spin_lock_claim_unused(true)); // 10 reports in the queue
    // turn on!
    hci_power_control(HCI_POWER_ON);

    return retValue;
}

'

[peterharperuk]

I'm a bit confused why you have to mess with the linker script. But it's a valid point, there are some better standalone BT examples in development https://github.com/raspberrypi/pico-examples/tree/new_bt_examples/pico_w/bt/standalone