Email: Password: Remember Me | Create Account (Free)

Back to Subject List

Old thread has been locked -- no new posts accepted in this thread
???
03/10/08 06:30
Read: times


 		 #152051 - One RS232 port and two devices
I am out of pins on this AT89C4051 design and must add a LCD display.

The RS232 port is being used to communicate with a small thermal printer at 9600 baud.

Would it work if I tied these same TX and RX lines to the serial input on the LCD display and set the software to send RS232 at 9600 baud when I want to communicate with the printer and set the RS232 to 19200 baud when I want to send data to the LCD display?

Would the printer's RS232 see a higher baud rate and ignore it and would the LCD see a lower baud rate and ignore it?

Any suggestions?

I would hate to put in a mechanical switch to select between the printer and the LCD display.

List of 32 messages in thread
TopicAuthorDate
One RS232 port and two devices            01/01/70 00:00      
   Almost certainly not!            01/01/70 00:00      
      neither one talks back            01/01/70 00:00      
         Soft-UART ?            01/01/70 00:00      
         Simplex            01/01/70 00:00      
            responses            01/01/70 00:00      
               The beaty of the 8051            01/01/70 00:00      
                  why all this about bit-banging            01/01/70 00:00      
               Bit banging UART TX.            01/01/70 00:00      
                  Easy to get wrong.            01/01/70 00:00      
                     Point taken, but you can calculate delay.            01/01/70 00:00      
                        Depends on compiler/etc...            01/01/70 00:00      
                           Don't use HLL!            01/01/70 00:00      
                              Cycle counting.            01/01/70 00:00      
                                 Fundamental flaw            01/01/70 00:00      
                              Not an Absolute....            01/01/70 00:00      
                                 RE: Never is a strong word            01/01/70 00:00      
                                    ... and            01/01/70 00:00      
                              assembly verses HLL            01/01/70 00:00      
                           Use a Timer IRQ to set the soft baudrate            01/01/70 00:00      
                              Surprise.            01/01/70 00:00      
                                 High risk            01/01/70 00:00      
                                    Straying into fantasy.            01/01/70 00:00      
                                       Not so fantastic?            01/01/70 00:00      
                  Resistance is too high            01/01/70 00:00      
                  Another reason why this is not so easy...            01/01/70 00:00      
               Timescales            01/01/70 00:00      
      message formatting            01/01/70 00:00      
         Try it now            01/01/70 00:00      
            It's OK now, thanks.            01/01/70 00:00      
   Two RS232 devices            01/01/70 00:00      
      the LCD display            01/01/70 00:00      

Back to Subject List