DA14592 BLE Notify Maximum 60 Bytes

Question

Hello, 
 I have used BLE peripheral example ( custom service + asy ) as reference where i have addded two characteristics in which i want to exchange 256 bytes of data. 
 I am able to send only 60 bytes of data to mobile application (tested nrf Connect for IOS) , 
 That is in firmware i made a provision that when i receive a certain command from BLE application the firmware should reply with these 256 bytes of data, 
 but when i check this in application i get only 60 data. 
 So please help me soo that i can get this data correct and full in one shot, 
 I had changed the MTU size to 512 bytes, but nothing changed

Regards Jc.

OV_Renesas · Answer

Hi JC, Apologies for the delay. I tried to replicate this on my side but I was not able. I used the Custom Service example from git: ble-sdk10-da1459x-examples/connectivity/ble_custom_service_example at main &middot; renesas/ble-sdk10-da1459x-examples I made the following changes: /* Just to demonstrate how notifications can be sent explicitly for dedicated attribute handles */
#define APP_NOTIF_DEMONSTRATION ( 1 )

/**
 * Attribute values maximum size expressed in bytes
 *
 * \warning The remote device must not exceed that number. Otherwise, the system will crash!!!
 *
 */
#define ATTR_MAX_SIZE ( 260 )
 
 Then at the end of the ble_peripheral_task.c file where we Notify data on the characteristics: #if APP_NOTIF_DEMONSTRATION
 /*
 * The following code is just for demonstration purposes to illustrate how notifications
 * can be sent explicitly for a specific attribute handle.
 * A connected peer device will receive notifications/indications only if has them enabled
 * explicitly. The notification type is defined automatically based on its associated
 * attribute declaration.
 */
 if (notif & NOTIF_TIMER_EVENT) {
 /* Generate a random number with the help of the TRNG engine */
 int arbitrary_value = rand();

 uint8_t test_val[256]= {0};
 for (int i=0;i<256;i++){
 test_val[i] = rand();
 }

 /* Send notifications for a specific attribute value (referenced by its UUID) */
 mcs_send_notifications(CHARACTERISTIC_ATTR_1_128_UUID,
 (const uint8_t *)&test_val, sizeof(test_val));

 mcs_send_notifications(CHARACTERISTIC_ATTR_4_128_UUID,
 (const uint8_t *)&arbitrary_value, sizeof(arbitrary_value));
 }
#endif On my side it works as expected. I am able to see the Characteristic of the 1st Service being notified every 5 seconds with 256 random bytes. Best regards, OV_Renesas