Please tell me how to connect one nRF51822 and another as Central and Peripheral. In the future, I would like to connect one Central and multiple Peripheral.

[tadanohito]

I am new to BLE.

My question is similar to the one below.

https://devzone.nordicsemi.com/f/nordic-q-a/22596/nrf51822-central-connect-and-communicate-with-2-peripherals

But the link to the answer was broken and I couldn't find it, so I'll ask.

I am using two nRF51822 and SDK12.3.0. I want to run them as Central on one side and Peripheral on the other. 

Probably by a method called GATT communication.(It means communication in a connected state.)

My goal is to record  RSSI and receiving time in Central when it receives an empty packet from Peripheral.

I would like to receive packets at intervals of 1msec to 10msec,

so advertising with long transmission intervals and randomly staggered transmission times would not achieve my goal.

In the future, I would like to receive packets from about 6 peripherals and record the RSSI of the packets.

Please let me know if there is a sample program or code that fits my purpose.

I'm not very good at English, so I use translation software to create my texts. I'm sorry if I don't make sense in some parts.

[awneil]

Note that nRF51 are not recommended for new BLE designs:

https://devzone.nordicsemi.com/f/nordic-q-a/13244/is-nrf52-recommended-over-nrf51-for-new-development/187456#187456 - and that was over 2 years ago.

tadanohito said:

the link to the answer was broken and I couldn't find it

That's always going to be a problem with going so far back.

Have you considered using nRF52 instead - so that you'll have up-to-date support ... ?

[tadanohito]

I understand that the nRF52 is better than the nRF51. Is it possible to achieve my goal with nRF52?

If multiple networks are difficult, what about 1:1 networks?

[Sigurd]

tadanohito said:

but it didn't show anything on teraterm. 

Nothing at all? You don't see e.g. "Multilink Example" printed either?

Also, I see you have 

printf("%d,", rssi);//RSSi

Try using NRF_LOG_INFO instead

NRF_LOG_INFO("RSSI: %d",rssi);

[tadanohito]

Thanks for your response.

Sigurd said:

Nothing at all? You don't see e.g. "Multilink Example" printed either?

Yes. Perhaps my "central" and "peripheral" have not moved to the connected state.

I tried "NRF_LOG_INFO", but the result was the same.

My project's "Perpheral", "ble_app_hrs", is still the default in SDK12.3.0, is there any inconvenience?

[Sigurd]

If you are not seeing any log output, then check if you have NRF_LOG_ENABLED set to 1 in sdk_config.h.

[awneil]

and that the NRF_LOG is not going to RTT ...

[tadanohito]

I reconfigured the settings, but nothing showed up.

Do I need to change any settings for NRF_LOG to observe it in TeraTerm?

I also changed the code a bit by referring to the following link, but the result was the same.

https://devzone.nordicsemi.com/f/nordic-q-a/10531/read-rssi-on-data-received-after-connection-in-s120

switch (p_ble_evt->header.evt_id)
    {
        // Upon connection, check which peripheral has connected, initiate DB
        // discovery, update LEDs status and resume scanning if necessary.
        case BLE_GAP_EVT_CONNECTED:
        {
int8_t p_rssi;
int8_t rssi = p_ble_evt->evt.gap_evt.params.adv_report.rssi;

// On the connection event

uint32_t m_conn_handle  = p_ble_evt->evt.gap_evt.conn_handle;  
err_code = sd_ble_gap_rssi_start(m_conn_handle, 10, 0);   
APP_ERROR_CHECK(err_code);

//On the RSSI_CHANGED event 
err_code = sd_ble_gap_rssi_get(m_conn_handle, &rssi);  
APP_ERROR_CHECK(err_code);

//printf("%d,", rssi);//RSSi
NRF_LOG_INFO("RSSI: %d",rssi);
double timenow = app_timer_cnt_get();
printf("%f,\r\n", (double) timenow); //nowtime

	


            err_code = ble_lbs_c_handles_assign(&m_ble_lbs_c[p_gap_evt->conn_handle],
                                                p_gap_evt->conn_handle,
                                                NULL);
            APP_ERROR_CHECK(err_code);

[awneil]

The settings would be easier to see in the Configuration Wizard:

Have you got the RTT configured to go over UART or RTT ?

TeraTerm won't see RTT ...

[tadanohito]

Is it a set like this?

awneil said:

Have you got the RTT configured to go over UART or RTT ?

I'm sorry, I don't understand well what you mean.

I also checked "NRF_LOG_BACKEND_SERIAL_USES_RTT".

https://devzone.nordicsemi.com/nordic/nordic-blog/b/blog/posts/debugging-with-real-time-terminal

awneil said:

TeraTerm won't see RTT ...

Does that mean I should check LOG? with other software or keil?

[awneil]

This bit says you have both RTT and UART enabled:

Sigurd - not sure if that's allowed?

[tadanohito]

I see.

I tried checking one side at a time, but it didn't work.

[tadanohito]

Am I using "ble_app_multilink" incorrectly?

I am using an evaluation board called EBSGCNZWY made by TAIYOYUDEN.

I'm using an evaluation board called EBSGCNZWY made by TAIYOYUDEN, and the number of LEDs is smaller than the sample expects.

I don't want to light up the LEDs, I just want to get the RSSI when connected to a specific "Peripheral".

Maybe I'm using the wrong code as a reference?