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APM_RC: fixed noisy PWM output on startup for APM2 

This reduces the number of rubbish pulses on the APM2 PWM output pins
on startup, which should help with booting some cheaper ESCs.

Thanks to Randy for the idea!
This commit is contained in:
Craig Elder 2012-09-10 08:07:50 +10:00 committed by Andrew Tridgell
parent 8f993cde2b
commit b667c6eb8c
1 changed files with 21 additions and 0 deletions
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21
libraries/APM_RC/APM_RC_APM2.cpp
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@ -81,8 +81,12 @@ APM_RC_APM2::APM_RC_APM2()
void APM_RC_APM2::Init( Arduino_Mega_ISR_Registry * isr_reg )
{
// --------------------- TIMER1: OUT1 and OUT2 -----------------------
digitalWrite(12,HIGH); // pulling high before changing to output avoids a momentary drop of the pin to low because the ESCs have a pull-down resistor it seems
digitalWrite(11,HIGH);
pinMode(12,OUTPUT); // OUT1 (PB6/OC1B)
pinMode(11,OUTPUT); // OUT2 (PB5/OC1A)
digitalWrite(12,HIGH); // pulling high before changing to output avoids a momentary drop of the pin to low because the ESCs have a pull-down resistor it seems
digitalWrite(11,HIGH);
// WGM: 1 1 1 0. Clear Timer on Compare, TOP is ICR1.
// CS11: prescale by 8 => 0.5us tick
@ -93,9 +97,15 @@ void APM_RC_APM2::Init( Arduino_Mega_ISR_Registry * isr_reg )
OCR1B = 0xFFFF;
// --------------- TIMER4: OUT3, OUT4, and OUT5 ---------------------
digitalWrite(8,HIGH);
digitalWrite(7,HIGH);
digitalWrite(6,HIGH);
pinMode(8,OUTPUT); // OUT3 (PH5/OC4C)
pinMode(7,OUTPUT); // OUT4 (PH4/OC4B)
pinMode(6,OUTPUT); // OUT5 (PH3/OC4A)
digitalWrite(8,HIGH);
digitalWrite(7,HIGH);
digitalWrite(6,HIGH);
// WGM: 1 1 1 0. Clear Timer on Compare, TOP is ICR4.
// CS41: prescale by 8 => 0.5us tick
@ -107,9 +117,15 @@ void APM_RC_APM2::Init( Arduino_Mega_ISR_Registry * isr_reg )
ICR4 = 40000; // 0.5us tick => 50hz freq
//--------------- TIMER3: OUT6, OUT7, and OUT8 ----------------------
digitalWrite(3,HIGH);
digitalWrite(2,HIGH);
digitalWrite(5,HIGH);
pinMode(3,OUTPUT); // OUT6 (PE5/OC3C)
pinMode(2,OUTPUT); // OUT7 (PE4/OC3B)
pinMode(5,OUTPUT); // OUT8 (PE3/OC3A)
digitalWrite(3,HIGH);
digitalWrite(2,HIGH);
digitalWrite(5,HIGH);
// WGM: 1 1 1 0. Clear timer on Compare, TOP is ICR3
// CS31: prescale by 8 => 0.5us tick
@ -123,8 +139,13 @@ void APM_RC_APM2::Init( Arduino_Mega_ISR_Registry * isr_reg )
//--------------- TIMER5: PPM INPUT, OUT10, and OUT11 ---------------
// Init PPM input on Timer 5
pinMode(48, INPUT); // PPM Input (PL1/ICP5)
digitalWrite(45,HIGH);
digitalWrite(44,HIGH);
pinMode(45, OUTPUT); // OUT10 (PL4/OC5B)
pinMode(44, OUTPUT); // OUT11 (PL5/OC5C)
digitalWrite(45,HIGH);
digitalWrite(44,HIGH);
// WGM: 1 1 1 1. Fast PWM, TOP is OCR5A
// COM all disabled.