| ??? 05/16/05 07:17 Read: times |
#93472 - Can't you... Responding to: ???'s previous message |
Tp Ow said:
Hi, I have search through the forum but yet to see any info on how to connect single Master and many slaves physically.
I cannot use other configuration, like RS422, RS485 because I got no more space on my small PCB. I am using At89RC51RC2 uP. I have about 100 slaves to link up to 1 master. I intend to do it this way. Master(tx) --> Slave1(Rx) --> Slave2 (rx) --> Slave3 (rx) ... 100 Master(rx) --> Slave1(tx) --> Slave2 (tx) --> Slave3 (tx) ... 100 Each Slave is uniquely addressed through a hardware DIP switch. 1) Is the TX line high impedance in UART mode? 2) Can I connect all the Slaves' RX line together. 3) What about all the Tx line together? My concern is if Slave100th starts transmitting, it will be sinking current from 100 devices, seems pretty scary to me. 4) Has anyone did this before? Thanks. Ow Maybe completely wrong, but I give it a try: Can't you work with the 9th bit (enhanced UART) which is available on the 8051? This way, you can address 256 different devices, if you indicate by means of the TB8 bit that the first byte is an address. Sorry if I catched the ball completely wrong, it's still early in the morning here... Best rgds, --Geert |
| Topic | Author | Date |
| Uart Automatic Address Recognition | 01/01/70 00:00 | |
| Can't you... | 01/01/70 00:00 | |
| SADDR and SADEN | 01/01/70 00:00 | |
| For This Application You Will Need.... | 01/01/70 00:00 | |
| Using RS485 | 01/01/70 00:00 | |
| Reasearch | 01/01/70 00:00 | |
| a comments | 01/01/70 00:00 | |
| Fan Out? | 01/01/70 00:00 | |
| Token Ring | 01/01/70 00:00 | |
| You do not have a clue do you..... | 01/01/70 00:00 | |
| How do you know it won't work. | 01/01/70 00:00 | |
| I'm done.... | 01/01/70 00:00 | |
| wrong connection | 01/01/70 00:00 | |
| Just for discussion purpose | 01/01/70 00:00 | |
| But adding your discrete components... | 01/01/70 00:00 | |
| outside of a board | 01/01/70 00:00 | |
| A Pickle | 01/01/70 00:00 | |
| Daisy Blue and Daisy Bell | 01/01/70 00:00 | |
| If you can't change it give it up | 01/01/70 00:00 | |
| If all boards had 10K collector pullups. | 01/01/70 00:00 | |
| horsefeathers | 01/01/70 00:00 | |
| Token Ring | 01/01/70 00:00 | |
| make it first, then design it | 01/01/70 00:00 | |
| 8052 serial communication | 01/01/70 00:00 | |
Off-Topic | 01/01/70 00:00 |