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David Prentice
01/21/12 07:00
Read: 443 times
Wormshill
England


 
#185602 - You MUST have digit drvers
Responding to: Per Westermark's previous message
To keep within the chip PORT ratings, the average multiplexed current per segment is fairly small (0.74mA).

With an 8051, you would have a port sink the current from the segments. The common-anode will be controlled via a PNP or driver chip. The peak digit current is high. e.g. 26mA sourced by the PNP. Traditional 8051 cannot source current anyway.

Yes. the display will be visible. Just not very bright. With a segment driver chip AND a digit driver chip, you can have a good display.

All the same, Anil's solution is very practical.

David.


List of 44 messages in thread
TopicAuthorDate
switch interfacing      Anil Kumar      01/11/12 00:38      
   What?      Per Westermark      01/11/12 00:58      
      switch interfacing      Anil Kumar      01/11/12 01:39      
         The 7-segment digits will not handle switches      Per Westermark      01/11/12 02:57      
   Perhaps this may be useful to you      Maunik Choksi      01/11/12 03:53      
      4 buttons - not full keypad      Per Westermark      01/11/12 04:39      
         switch interfacing      Anil Kumar      01/12/12 00:06      
            That is called edit mode      Maunik Choksi      01/12/12 01:55      
               switch interfacing      Anil Kumar      01/12/12 22:50      
                  You need to study some examples      Maunik Choksi      01/12/12 23:51      
                     switch interfacing      Anil Kumar      01/13/12 00:10      
                  Details details - and where is debounce/repeat handling?      Per Westermark      01/13/12 01:20      
                     switch interfacing      Anil Kumar      01/14/12 00:59      
            Why should this be a problem??      Kai Klaas      01/12/12 07:53      
            interfacing your switches has nothing to do with LED's      Richard Erlacher      01/12/12 22:02      
   MUX LED AS O/P PIN      Satish S Munot      01/14/12 19:47      
      Switch interfacing      Anil Kumar      01/19/12 23:19      
         divide and conquer      Mahmood Elnasser      01/20/12 01:35      
         simplified step-by-step way to post your schematic        KONSTANTINOS L. ANGELIS      01/20/12 02:12      
            remember      Erik Malund      01/20/12 07:31      
               ? Not Muxing ?      Michael Karas      01/20/12 08:17      
   switch interfacing      Anil Kumar      01/21/12 01:57      
      You need lots of resistors      David Prentice      01/21/12 04:34      
         (Back to) Basics      Andy Neil      01/21/12 05:17      
            multiplex 5 digits      David Prentice      01/21/12 05:43      
               Don't think anyone would want 1:35 degenerate "multiplexing"      Per Westermark      01/21/12 05:52      
                  Have I done the sums wrong?      David Prentice      01/21/12 06:06      
                     No but multiplexing requires few driver lines      Per Westermark      01/21/12 06:17      
                        You MUST have digit drvers      David Prentice      01/21/12 07:00      
                           You missed '4094 OE+PWM for luminocity      KONSTANTINOS L. ANGELIS      01/21/12 09:47      
               No multiplexing needed...      Kai Klaas      01/21/12 07:33      
                  switch interfacing      Anil Kumar      01/21/12 07:46      
                     What help?      Andy Neil      01/21/12 08:33      
                     how?      Erik Malund      01/21/12 08:34      
                     Ah, a homework, right?      Kai Klaas      01/21/12 09:21      
                        switch interfacing      Anil Kumar      01/21/12 09:55      
                           language?      Erik Malund      01/21/12 10:37      
                           i have no logical idea how i write code      Andy Neil      01/21/12 10:40      
                           You need...      Kai Klaas      01/22/12 07:07      
                              Making a seven segment display blink      Andy Neil      01/22/12 07:19      
                                 The 4094 chip has an OE pin      David Prentice      01/22/12 07:48      
                              switch interfacing      Anil Kumar      01/22/12 10:57      
   switch interfacing      Anil Kumar      01/31/12 22:07      
      would you provide some feedback ?      KONSTANTINOS L. ANGELIS      02/01/12 03:35      

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