Converting BLE_peripheral UART example to support 4 peripheral connections

RE: Converting BLE_peripheral UART example to support 4 peripheral connections

A sudheer Kumar — Mon, 12 Sep 2022 11:20:51 GMT

Hi,

changed my function little bit, now it's working

void vfnSendSensorResponsOnBle(uint8_t *ptr, uint32_t len)
{
uint8_t uIndex = 0;
uint32_t err_code = 0;
ble_conn_state_conn_handle_list_t conn_handles = ble_conn_state_periph_handles();

for (uint32_t i = 0; i < conn_handles.len; i++)
{
if ((ble_conn_state_valid(conn_handles.conn_handles[i])==true))
{
NRF_LOG_DEBUG("Ready to send data over BLE NUS");

do
{
err_code = ble_nus_data_send(&m_nus, ptr, (uint16_t *)&len, conn_handles.conn_handles[i]);
if ((err_code != NRF_ERROR_INVALID_STATE) &&
(err_code != NRF_ERROR_RESOURCES) &&
(err_code != NRF_ERROR_NOT_FOUND))
{
APP_ERROR_CHECK(err_code);
}

} while (err_code == NRF_ERROR_RESOURCES);
}
}
}

and also able to send 253 bytes long string with all the central devices by changing the RAM size.

thank you every one!

RE: Converting BLE_peripheral UART example to support 4 peripheral connections

Hieu — Mon, 12 Sep 2022 11:04:27 GMT

That's good to hear. If you don't mind, please share what the problem is and verify it as the answer, so that future developers can refer from it.

Sure, you can increase MTU size by updating that exact config. You can refer to the UART/Serial Port Emulation over BLE (or ble_app_uart) example for a working configuration. You could also discover DevZone for more information on how-to, common issues, and more details.

If you need further help with that, please open a new ticket, as that would be a different topic from what we are discussing here.

RE: Converting BLE_peripheral UART example to support 4 peripheral connections

A sudheer Kumar — Mon, 12 Sep 2022 10:43:15 GMT

Hi,

Thanks for reply!

I am able to share strings up to four central devices , but I am facing challenge with string size.

Unable to send more than 20 characters because of NRF_SDH_BLE_GATT_MAX_MTU_SIZE 23, is there any other option to send up to 128 or 256 characters long Over BLE

RE: Converting BLE_peripheral UART example to support 4 peripheral connections

Hieu — Mon, 12 Sep 2022 09:43:28 GMT

Hi there, I am taking over from Susheel as he is not available. I checked your information and assume that you are working with a nRF5 SDK version where ble_nus.c supports this function:

ble_nus_data_send(ble_nus_t * p_nus, uint8_t * p_data, uint16_t * p_length, uint16_t conn_handle)

That is because that with such versions, the ble_nus module should support multiple connections out of the box (unlike earlier versions where you do need to modify it).

And your code seems to be correct. I have also successfully sent text to two central devices using a very similar implementation I will post below.

While implementing that from a fresh example, I also notice that, depends on implementation, UART lib, NUS and multiple link support can eat up a lot of memory. Your description of "peripheral device getting restarted" is a symptom that the device might have run out of RAM. Or it could be that some pointers are not being handled correctly. Please also check if you are building with "Release" configuration. In default "Release" build config, the device would just reset at any failed APP_ERROR_CHECK.

Could you please configure log level to DEBUG in sdk_config.h and debug some more with RTT logs? You might want to try both Debug and Release build configurations to see how it changes things.

If you need support with that, please produce a clean log of the peripheral application, in Debug build configuration, failing and restarting and reply here.

Finally, this is my current implementation which successfully sends to two centrals:

void dummy_nus_send(void)
{
    uint32_t       err_code;
    static uint8_t data_array[] = "dummy\r\n";
    for (uint32_t i = 0; i < NRF_SDH_BLE_PERIPHERAL_LINK_COUNT; i++)
    {
        if (m_qwr[i].conn_handle != BLE_CONN_HANDLE_INVALID)
        {
            NRF_LOG_DEBUG("Ready to send data over BLE NUS Conn %d of %d, handle %x", i, NRF_SDH_BLE_PERIPHERAL_LINK_COUNT, m_qwr[i].conn_handle);
            do
            {
                uint16_t length = (uint16_t) sizeof(data_array);
                err_code = ble_nus_data_send(&m_nus, data_array, &length, m_qwr[i].conn_handle);
                if ((err_code != NRF_ERROR_INVALID_STATE) &&
                    (err_code != NRF_ERROR_RESOURCES) &&
                    (err_code != NRF_ERROR_NOT_FOUND))
                {
                    APP_ERROR_CHECK(err_code);
                }
            } while (err_code == NRF_ERROR_RESOURCES);
            
        }
    }
}

RE: Converting BLE_peripheral UART example to support 4 peripheral connections

A sudheer Kumar — Mon, 12 Sep 2022 05:23:23 GMT

Is there any one to help me out

RE: Converting BLE_peripheral UART example to support 4 peripheral connections

A sudheer Kumar — Thu, 08 Sep 2022 08:13:58 GMT

thanks for your reply

RE: Converting BLE_peripheral UART example to support 4 peripheral connections

Susheel Nuguru — Thu, 08 Sep 2022 08:07:11 GMT

I might have done this as a hobby project few years back but unfortunately I cannot find traces of it.

It is definitely possible to modify the example and ble_nus module to handle multiple connections with central, and could be done in a week effort. But unfortunately, I cannot help with the code, sorry.

RE: Converting BLE_peripheral UART example to support 4 peripheral connections

A sudheer Kumar — Thu, 08 Sep 2022 05:22:01 GMT

thanks for the example,

Actually I am looking for NUS peripheral that can support multiple centrals

RE: Converting BLE_peripheral UART example to support 4 peripheral connections

Susheel Nuguru — Thu, 08 Sep 2022 05:13:00 GMT

If you are looking for a NUS central that can support multiple peripherals, you can try to look at this github project.

RE: Converting BLE_peripheral UART example to support 4 peripheral connections

A sudheer Kumar — Thu, 08 Sep 2022 04:34:59 GMT

Hi Susheel,

Thanks for your reply,

I searched in Devzone, but didn't get any related links regarding my issue. If you have any, please share us.

You need to make changes to the Nordic UART service data structures to handle multi instance connections. At the moment, it is a single connection only module (out of the box)

what are the changes need do, which example will help me to solve this issue

Regards,

Sudheer

RE: Converting BLE_peripheral UART example to support 4 peripheral connections

Susheel Nuguru — Wed, 07 Sep 2022 15:41:20 GMT

I believe there was some requests similar to this before in devzone. Have you tried to search for them here?

In the nutshell, it is possible, but need some changes to the ble_nus module. You need to make changes to the Nordic UART service data structures to handle multi instance connections. At the moment, it is a single connection only module (out of the box)