main.cpp

00001 #include "mbed.h"
00002 #include "tsi_sensor.h"
00003  
00004 // Simple button/swipe library for FRDM-KL25Z
00005 // AI Williams -- The Touch of a Button
00006 // Dr.Dobb's Journal
00007 // http://www.drdobbs.com/embedded-systems/the-touch-of-a-button/240169431 
00008  
00009 /* This defines will be replaced by PinNames soon */
00010 #if defined (TARGET_KL25Z) || defined (TARGET_KL46Z)
00011   #define ELEC0 9
00012   #define ELEC1 10
00013 #elif defined (TARGET_KL05Z)
00014   #define ELEC0 9
00015   #define ELEC1 8
00016 #else
00017   #error TARGET NOT DEFINED
00018 #endif
00019  
00020 // Define the "zones" considered to be buttons
00021 // 4 is about the limit and 3 might be even better
00022 // You could also equal space them automatically pretty easily
00023 // (e.g., specify 25% and fill in BTNMAX programmatically 
00024 float BTNMAX[]= {0.25, 0.50, 0.75, 1.00 };
00025 #define SWIPETIME .350  // seconds to wait before sensing a button push or swipe
00026 #define SWIPE_R 256     // virtual button code for right swipe
00027 #define SWIPE_L 512     // virtual button code for left swipe
00028  
00029 Serial pc(USBTX, USBRX); // tx, rx  for debugging
00030 TSIAnalogSlider tsi(ELEC0, ELEC1, 40);  // The Analog slider
00031 Timeout scan;
00032  
00033  
00034 int candidate=-1;     // possible button push (-1 is none)
00035 volatile int realbtn=-1;  // actual button push (-1 is none)
00036 volatile int hold=0;   // waiting for button release when 1
00037  
00038 // internal function to get raw button state
00039 int getrawbtn()
00040 {
00041     float v=tsi.readPercentage();  // read slider
00042     if (v==0.0) return -1;         // no button at all
00043     for (int i=0;i<sizeof(BTNMAX)/sizeof(BTNMAX[0]);i++)   // classify by zone
00044         if (v<BTNMAX[i]) return i;
00045     return -1;  // what?
00046 }
00047  
00048 // This is called by the timeout to 
00049 // either see there is no swipe
00050 // see that there is a swipe
00051 // or see that there is a button release
00052 void checkbtn(void)
00053 {
00054     int newbtn=getrawbtn();
00055     if (hold!=0 && newbtn==-1)  // wait for key release
00056     {
00057         hold=0;   // released so
00058         return;  // don't reschedule me
00059     }
00060     // reschedule us for next swipetime
00061     scan.attach(checkbtn,SWIPETIME);
00062     if (hold) return;  // still waiting for release
00063     hold=1;            // we will be waiting for release from now on
00064     if (newbtn==-1||newbtn==candidate)   // if no touch or button is the same, the candidate is the button
00065     {
00066         realbtn=candidate; 
00067         return;
00068     }
00069     // Otherwise we are swiping either left or right
00070     if (candidate<newbtn) realbtn=SWIPE_L; else realbtn=SWIPE_R;
00071     return;
00072 }
00073  
00074 // This is the main API
00075 // Call it to get a button code (0-3 or 256 or 512)
00076 // You can block or not (default is to block)
00077 int getbtn(bool kwait=true)
00078 {
00079     while (hold)  // if holding, either wait or return
00080     {
00081         if (!kwait) return -1;
00082     }
00083     realbtn=-1;    // mark that we don't know
00084     do
00085     {
00086         candidate=getrawbtn();   // get a candidate (or return if not waiting)
00087     } while (candidate==-1 || !kwait);
00088     if (candidate==-1) return -1;
00089     scan.attach(checkbtn,SWIPETIME);  // schedule the checkbtn routine
00090     while (realbtn==-1);    // wait for realbtn to get set
00091     return realbtn;   // return it
00092 }
00093  
00094 // Simple test program
00095 int main(void) {
00096      
00097     while (true) {
00098        pc.printf("Button %d\r\n",getbtn());
00099     }
00100 }