| ??? 04/15/08 13:18 Read: times |
#153376 - Surely the master needs to know its slaves?! Responding to: ???'s previous message |
Ap Charles said:
The problem is , the master cannot poll the slaves as address keeping by the master for unknown number of slaves is difficult. But, surely, it is absolutely fundamental and essential that the master must know what slaves it has?! It's not particularly difficult - it just requires a Master with adequate resources. Hence there must be a practical limit on the number of slaves supported by any specific master, surely? For a network like this, you should expect the Master to have significantly greater resources than the slaves - possibly by an order (or orders) of magnitude! Earlier you said it right that slaves should broadcast randomly , that would help master know how many are there. No, it wouldn't: the master would still have to keep a record of the current "known" slaves - otherwise, how could it tell whether a slave was "known" or not?! if we put a random number for the slaves to broadcast , there could be collisions ? Of course there would - that's why you need some form of collision avoidance and/or detection and recovery! Also they may waste power unnecessarily if the master isnt present. True - which is an advantage of having the Master do the polling, isn't it? Again, all these issues are already solved in available commercial solutions - how much time can you afford to take in re-inventing this particular wheel? |
