Project Logs

Collapse logs

• Video demonstration of touch interface

  Shaos • 03/07/2017 at 04:54 • 0 comments

  Source code: https://github.com/shaos/xorlib/blob/master/examples/scifixer.c

• Reading touch sensors

  Shaos • 03/06/2017 at 07:52 • 0 comments

  In order to read touch sensors (they will be implemented as part of PCB) we need to connect internal pull-ups to those pins then to read we should set pins out, clear pins and set pins in then read a few times (until parasitic capacitor is fully charged through internal pull-up) and analyze (touched pads charge longer):

  int tch[4],cc[5],c,i;
  ConfigCNBPullups(CNB8_PULLUP_ENABLE|CNB9_PULLUP_ENABLE|CNB10_PULLUP_ENABLE|CNB11_PULLUP_ENABLE);
  ....
  // somewhere in the game loop:
   tch[0]=tch[1]=tch[2]=tch[3]=5;
   mPORTBSetPinsDigitalOut(BIT_8|BIT_9|BIT_10|BIT_11);
   mPORTBClearBits(BIT_8|BIT_9|BIT_10|BIT_11);
   mPORTBSetPinsDigitalIn(BIT_8|BIT_9|BIT_10|BIT_11);
   cc[0] = mPORTBRead();
   cc[1] = mPORTBRead();
   cc[2] = mPORTBRead();
   cc[3] = mPORTBRead();
   cc[4] = mPORTBRead();
   for(i=0;i<5;i++)
   {
    c = cc[i];
    if((c&BIT_8) && tch[0]==5) tch[0]=i;
    if((c&BIT_9) && tch[1]==5) tch[1]=i;
    if((c&BIT_10) && tch[2]==5) tch[2]=i;
    if((c&BIT_11) && tch[3]==5) tch[3]=i;
  }

  tch[4] are states for 4 touch sensors - if respective number is greater than 1 then sensor is "touched". Experiment showed that if nothing is touched array will have all 1s, but if one or more sensors touched - respective value will go up (usually 3 if one sensor was touched or 2 if more than one sensor were touched). Interesting fact that it's relatively easy to detect intermediate finger position when it touches 2 neighboring sensors so with 4 pads we got 8 positions (or even 9 if we count center position as well).

• First run

  Shaos • 03/06/2017 at 06:02 • 0 comments

  Xorya-touch in action (connected to TV and PICKit3):

  for now it shows static image 320x200 with 2 half-frames (it's drawn as 160x400 with interlace):

• Xorya-touch

  Shaos • 03/06/2017 at 05:59 • 0 comments

  This is the next prototype of #XORYA - extremely low cost game console on PIC32 with capacitance touch interface where 4 pads connected to RB8, RB9, RB10 and RB11 (and there is a ground ring around them):
  

  Pads covered by scotch tape because we will measure capacitance of the "touch"...

View all 4 project logs