The SoftDevice allows the number of Security Manager Protocol (SMP) instances available for all connections operating in central role to be specified by the application.
At least one SMP instance is needed in order to carry out
SMP operations for central role connections, and a
SMP instance can be shared amongst multiple central
role connections. A larger number of SMP instances will
allow multiple connections to have ongoing concurrent SMP
operations, but this will result in increased RAM usage by the SoftDevice. The number of
SMP instances is specified through
sd_ble_cfg_set.