Diff: throttle.cpp

Revision:

1:8ef34deb5177

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/throttle.cpp	Mon Nov 13 09:53:00 2017 +0000
@@ -0,0 +1,56 @@
+/*
+This file about using model control servo to drive the throttle of Honda GX120 engine
+
+Using a model control servo to set the throttle of Honda GX120 petrol engine
+First thoughts  12 Nov 2017.
+
+Servo driven by positive pulse of duration 1000 to 2000 micro sec. Repetition rate 50Hz
+Will first try repeating in 32ms loop giving repetirion rate approx 30 Hz.
+Pos pulse generated by setting to 1 in 32ms handler and starting a 'timeout'
+
+    ... as part of 32ms code
+    if  (torque_demand < 0.01)  {
+        throttle    (TICKOVER);
+    }
+    else    {   //  got positive torque demand
+        throttle    (MID_REVS);
+    }
+    throttle_servo_pulse_out = 1;
+    throttle_servo_pulse_width.attach_us    (&servo_pulse_lo, global_throttle_us);
+*/
+#include "mbed.h"
+#include "Electric_Loco.h"
+
+static const   int
+    SERVO_RANGE     = 1000, //  micro sec difference between max and min
+    SERVO_OFFSET    = 1000, //  min servo pulse width micro sec
+    TICKOVER        = SERVO_OFFSET + 0,
+    MID_REVS        = SERVO_OFFSET + 500,
+    RANGE_MULTIPLIER    = SERVO_RANGE + SERVO_OFFSET - MID_REVS;
+
+DigitalOut  throttle_servo_pulse_out    (D8);   //  now defined in throttle.cpp
+
+Timeout throttle_servo_pulse_width;
+
+void    throttle_servo_pulse_lo  ()  {   //  Interrupt handler called at end of 'Timeout'
+    throttle_servo_pulse_out = 0;   //  end servo positive pulse
+}
+
+int throttle    (double torque_demand, double speed_mph)    {   //  called from main every 31ms
+    int duration_us;
+    if  (throttle_servo_pulse_out != 0)
+        return  -1; //  pulse positive already
+    if  (torque_demand < 0.01)  {
+        duration_us = TICKOVER;
+    }
+    else    {   //  got positive torque demand
+        double  tmpd = torque_demand * RANGE_MULTIPLIER;
+        duration_us = MID_REVS + (int) tmpd;
+    }
+    throttle_servo_pulse_out = 1;   //  start servo positive pulse
+    throttle_servo_pulse_width.attach_us    (&throttle_servo_pulse_lo, duration_us);
+    return  0;
+}
+//  endof New Nov 2017    Controlling throttle of Honda engine
+
+