'sweeplf' tells us antenna's resonant frequency

diff --git a/armsrc/appmain.c b/armsrc/appmain.c
index 27a7551d55d06b680b35999321f6b072b3d1a55a..e7b868bd811dc5044a3661c5e47184b5c8d48b98 100644 (file)
--- a/armsrc/appmain.c
+++ b/armsrc/appmain.c
@@ -241,7 +241,9 @@ static int AvgAdc(int ch)
 void SweepLFrange()
 {
        BYTE *dest = (BYTE *)BigBuf;
-       int i;
+       BYTE dummy[12];
+       int i, peak= 0, ptr= 0;
+       double freq;
 
        // clear buffer
        memset(BigBuf,0,sizeof(BigBuf));
@@ -251,7 +253,28 @@ void SweepLFrange()
                FpgaSendCommand(FPGA_CMD_SET_DIVISOR, i);
                SpinDelay(20);
                dest[i] = (137500 * AvgAdc(ADC_CHAN_LF)) >> 18;
+               if(dest[i] > peak) {
+                       peak= dest[i];
+                       ptr= i;
+                       }
        }
+       dummy[11]= '\0';
+       dummy[10]= 'z';
+       dummy[9]= 'H';
+       dummy[8]= 'k';
+       dummy[7]= ' ';
+       freq= 12000000/(ptr + 1);
+       for(i= 6; i > 3 ; --i) {
+               dummy[i]= '0' + ((int) freq) % 10;
+               freq /= 10;
+               }
+       dummy[3]= '.';
+       for(i= 2; i >= 0 ; --i) {
+               dummy[i]= '0' + ((int) freq) % 10;
+               freq /= 10;
+               }
+       DbpString("Antenna resonates at:");
+       DbpString(dummy);
 }
 
 void MeasureAntennaTuning(void)