A phenomenon in which NUS's Central stops midway while performing a BLE scan.

Question

hello. 
 
 I have two NUS Centrals running at the same time. BLE Scan continues to run during standby.

static void scan_start(void)
{
&#160; &#160; ret_code_t ret;

&#160; &#160; printf("> Scanstart ");
&#160; &#160; ret = nrf_ble_scan_start(&m_scan);
&#160; &#160; APP_ERROR_CHECK(ret);

&#160; &#160; Bsp_led_indication_Scanning_clr();
&#160; &#160; ret = bsp_indication_set(BSP_INDICATE_SCANNING); // connection LED
&#160; &#160; APP_ERROR_CHECK(ret);

}

The problem is that when the peripheral PCB is turned on while the two Centrals are performing BLE Scan, One connection is made to the Central, and the other one stops while scanning. There is no problem with other operations, only the BLE Scan stops. 
 
 Why is this like this? Also, is there a way to check whether BLE SCAN is operating and restart it if BLE SCAN is stopped?

David_Kim · Accepted Answer

Something somewhat strange happened. 
 I created a new and improved PCB, and the above problem disappeared. 
 
 What was improved 
 - Modify the load capacitor value of the 32.768kHz crystal in the peripheral (refer to the formula) 
 - Fixed 2-pin GND disconnection among 4 pins of peripheral and central 32Mhz Crystal - Change peripheral CONN_INTERVAL related parameters

[ after ] 
 #define MIN_CONN_INTERVAL MSEC_TO_UNITS(20, UNIT_1_25_MS) /**< Minimum acceptable connection interval (20 ms), Connection interval uses 1.25 ms units. */ #define MAX_CONN_INTERVAL MSEC_TO_UNITS(75, UNIT_1_25_MS) /**< Maximum acceptable connection interval (75 ms), Connection interval uses 1.25 ms units. */ #define SLAVE_LATENCY 0 /**< Slave latency. */ #define CONN_SUP_TIMEOUT MSEC_TO_UNITS(4000, UNIT_10_MS) /**< Connection supervisory timeout (4 seconds), Supervision Timeout uses 10 ms units. */ 
 [ Before ] 
 //#define MIN_CONN_INTERVAL MSEC_TO_UNITS(400, UNIT_1_25_MS) /**< Minimum acceptable connection interval (20 ms), Connection interval uses 1.25 ms units. */ //#define MAX_CONN_INTERVAL MSEC_TO_UNITS(500, UNIT_1_25_MS) /**< Maximum acceptable connection interval (75 ms), Connection interval uses 1.25 ms units. */ //#define SLAVE_LATENCY 5 /**< Slave latency. */ //#define CONN_SUP_TIMEOUT MSEC_TO_UNITS(10000, UNIT_10_MS) /**< Connection supervisory timeout (4 seconds), Supervision Timeout uses 10 ms units. */

A phenomenon in which NUS's Central stops midway while performing a BLE scan.

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