Multiple Connections of nRF51822

Question

Hello, 
 lets suppose, there are 20 nRF51822 chip advertise there presence at a same time. 
 so, this all are acts as a slave at a time. now, the master(mobile or nrf51822 chip) scan all peripheral device and see the all 20 slave presence. 
 now can this one master can connect this all 20 slave at a time? 
 is there parallel data transmitting and receiving are configurable from/to master to/from slaves? 
 means at a time 20 image are send in all 20 salve device through one master? 
 this 20 number is only for assumption. in reality this number is more than 100. 
 please correct me if i am wrong. 
 Thank You
Milav

endnode · Accepted Answer

Hi milav, all these questions are linked only to BLE stack capabilities. When it comes to Nordic stacks for nRF51 (S130 V2) their capabilities are clearly explained in respective documentation on Infocenter : up to 8 GAP Central (Master) parallel connections supported. But if you go with some other stacks you might be able to go up to 20, 32 or more (who knows). Anyway all BLE connections (as well as other Bluetooth versions - not counting Bluetooth mesh) are peer to peer so whatever is happening on one connection is "logically" independent on what is happening on others. If you run these on one system (e.g. on single chip/firmware like nRF51 case you draw above) then you can somehow link/handover the data on the highest (APP) layer which lets you achieve more interesting topologies but that's purely your business, nothing to do with lower stack or HW. Just note that more connections you maintain lower bandwidth each of them has. And this is nothing you can largely influence, each stack has typically some lower limits on connection intervals when maintaining certain number of parallel connections. 
 So no, if you connect 20 "slaves" in star configuration to one "master" they cannot receive the same data, each packet from the master must go to one slave at the time.