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Dan Henry
08/28/05 09:54
Read: 980 times
Boulder, Co
U.s.a.


 
#100213 - UARTs and ASK
Responding to: Manoz Joshi's previous message
Manoz Joshi said:
Unfortunately the RF link was not very stable as LED didn't switch on straight away after pressing one of the button. Sometime the LED switched on without me pressing the button.

Look at the receiver output with a scope and see how much noise is present and whether you expect a UART to clock in the data properly. You see, it takes only something with the appearance of a start bit to get the UART started shifting in bits.

A UART's NRZ plus start bit encoding scheme is not a good choice for ASK, although some folks have employed different encoding schemes at a higher level that account for the UART's start and stop bits and then just use the UART to clock out the bits.

I have been informed that if I use bit-banging at the receiver instead of UART, would solve the problem. I don't know it is true or not.

And most likely bit-banging at the transmitter too. Bit-banging transmit and receive are done when internal peripheral subsystems in incapable of generating the waveform of the encoding scheme chosen to suit the RF link's characteristics.

List of 34 messages in thread
TopicAuthorDate
Serial RF with AT89C51 to AT89C51      Manoz Joshi      08/28/05 07:35      
   Lineks ?      Steve M. Taylor      08/28/05 09:31      
   UARTs and ASK      Dan Henry      08/28/05 09:54      
      Software driven UART - Bit-banging      Manoz Joshi      08/28/05 17:23      
         Channel coding        Dan Henry      08/29/05 07:16      
            Yes but...      Manoz Joshi      08/29/05 13:47      
               What is the hardware UART not doing?      Dan Henry      08/29/05 14:27      
                  Hardware UART      Manoz Joshi      08/29/05 19:08      
                     RF links pose challenges, but anyway...      Dan Henry      08/29/05 20:58      
                     Spend the money or do the hard work?      Andy Neil      08/30/05 00:56      
                        So many, so often, forget that design is      Erik Malund      08/30/05 07:10      
   Rendering      Steve M. Taylor      08/30/05 09:06      
      Me too !      Farshid Jafari Harandi      08/30/05 09:21      
      nope, just like any other (IE)      Erik Malund      08/30/05 11:13      
         Disappointed!      Manoz Joshi      08/30/05 13:58      
            What is the purpose of "learning" our co      Erik Malund      08/30/05 14:40      
            Sorry but      Steve M. Taylor      08/30/05 14:43      
            End of wrong stick?      Andy Neil      08/30/05 16:42      
            Learning? Dealing with disappoinment      Dan Henry      08/30/05 18:01      
            What you need to learn      Andy Neil      08/31/05 03:31      
               Apology      Manoz Joshi      08/31/05 08:03      
                  Recommendation      Andy Neil      08/31/05 09:25      
                  A short backgrounder      Dan Henry      08/31/05 11:26      
                     Missing the point      Russell Bull      09/01/05 03:50      
   The wise men have spoken      Dan Henry      08/30/05 18:09      
   UARTs, the last word Mr. Joshi      Dan Henry      08/30/05 18:13      
      *Groan* Here is my inital code      Manoz Joshi      08/31/05 01:39      
         Does it work ?      Steve M. Taylor      08/31/05 01:53      
            Does it work at all?      Andy Neil      08/31/05 03:53      
         The Point.      Andy Neil      08/31/05 03:46      
            why analyze how deep the water is before      Erik Malund      08/31/05 07:14      
         TF2 needs to be cleared in interrupt      Charles Bannister      08/31/05 04:54      
         the right way to get help definitely is      Erik Malund      08/31/05 07:05      
         Pinching a loaf      Dan Henry      08/31/05 18:47      

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