'  Name    : brushless_converter.BAS                                   
'  Author  : Christopher Good                    
'  Notice  : Copyright (c) 2010                                
'          : All Rights Reserved                               
'  Date    : 19 May 2010                                          
'  Version : 1.0                                               
'  Notes   : Free source code. Compile with Proton IDE Lite (also free).  Program your PIC with IC-Prog (also free). 
'          This code reads the gate input on the FETs on a Draganfly brushed quadcopter,
'          and scales the 0 to 5.8 ms high pulse to a servo nominal 1..2 ms PWM.                                          
' 
'          Pin8 = Ground                  - tie to common, connect to pin 1 via .1MF cap 
'          Pin7 = GPIO.0  - i/o           - PWM 1..2 ms output
'          Pin6 = GPIO.1  - i/o           -  
'          Pin5 = GPIO.2  - i/o           - 
'          Pin4 = GPIO.3  - input only    - FET gate #1 - tie to FET via 4.7k ohm resistor
'          Pin3 = GPIO.4  - i/o           - 
'          Pin2 = GPIO.5  - i/o           - 
'          Pin1 = Vcc                     - tie to +5v, connect to pin 8 via .1MF cap


Device 12C508
Config INTRC_OSC, MCLRE_OFF, WDT_OFF, CP_OFF        ' set config fuses
OPTION_REG.5 = 0                                    ' clock source internal(4 MHz)

xtal = 4 
PULSIN_MAXIMUM = 1200                               ' wait a maximum of 12 ms for a pulse                   
Dim S1         aS wORD
Dim Scaled_S1  AS Word
Clear                                               ' set all variables = 0

Start:

  S1 = Pulsin GPIO.3, High                          ' should be in range 0 to 580 (0 ...  5.8 ms)
  if S1 > 580 Then S1 = 580 
  Scaled_S1 = (S1 * 100) / 580                      ' scale to 0 .. 100 (0 ... 1 ms) 
  Low GPIO.0                                        ' set the output pin state to low
  PulsOut GPIO.0, Scaled_S1 + 100                   ' add 100 (1 ms) to get in range of 1 ... 2 ms

  'if s1 > 0 then delayms 12 else delayms 6         ' if the pulse exists at all, wait about 12 ms to get the next one
                                                    ' if there was no pulse, the code waited 12 ms, so wait another 6 to try again
                                                    
  DelayMS ( 11 - (S1 / 100) - (Scaled_S1/100))      ' make the frame rate >12 ms
 
  Goto Start