3.3v to 5v converter (Episode 2/5)

Conversion between the 3.3v to 5v logic signal.

.from: http://www.edaboard.com/thread11539.html

Hot to do an 5V signal will be level-shift to 3.3V and the 3.3V signal will pass-thru directly without attentuation.

Solution 1:

My simple method is to use serial resistor divider (few kilos, ie. 10kR) and diode (Schottky diode) to +3.3V (A - resistor, K - +3.3V).

Solution 2:

look 74LVC series chips, that's also available in very small one gate package ( and it is very low cost, for example the Philips 74LVC1G125GW or Texas Instruments SN74LVC1G125DCKR chips in small 5 pim SC-70-5 packege, low unit cost

Solution 3:

Take a look at www.chipcon.com in Application Note AN021. Texas Instruments has a similar good  PDF appnote also.

MBED: UDP Socket Example 1 (Cookbook)

.from: http://mbed.org/users/donatien/programs/UDPSocketExample/5yuvy

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#include "mbed.h"
#include "EthernetNetIf.h"
#include "UDPSocket.h"

EthernetNetIf eth;
UDPSocket udp;

void onUDPSocketEvent(UDPSocketEvent e)
{
  switch(e)
  {
  case UDPSOCKET_READABLE: //The only event for now
    char buf[64] = {0};
    Host host;
    while( int len = udp.recvfrom( buf, 63, &host ) )
    {
      if( len <= 0 )
        break;
      printf("From %d.%d.%d.%d: %s\n", host.getIp()[0], host.getIp()[1], host.getIp()[2], host.getIp()[3], buf);
    }
    break;
  }
}

int main() {
  printf("Setting up...\n");
  EthernetErr ethErr = eth.setup();
  if(ethErr)
  {
    printf("Error %d in setup.\n", ethErr);
    return -1;
  }
  printf("Setup OK\n");
 
  Host multicast(IpAddr(239, 192, 1, 100), 50000, NULL); //Join multicast group on port 50000

  udp.setOnEvent(&onUDPSocketEvent);
 
  udp.bind(multicast);
 
  Timer tmr;
  tmr.start();
  while(true)
  {
    Net::poll();
    if(tmr.read() > 5)
    {
      tmr.reset();
      const char* str = "Hello world!";
      udp.sendto( str, strlen(str), &multicast );
      printf("%s\n", str);
    }
  }

 
}

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