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ArduPPM: PWM to PPM mode

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PPM polarity reversing was not working when changing the Output PPM pin level before timer 1 / output compare init. The compare generator initialization was reverting the pin to low level. Instead of that a force match compare is used after timer / compare generator init to set the PPM output to high level.
This commit is contained in:
Olivier ADLER 2012-11-03 00:54:57 +01:00
parent c5b68b17cd
commit 70c6739fbf
1 changed files with 7 additions and 5 deletions
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12
Tools/ArduPPM/Libraries/PPM_Encoder.h
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@ -259,6 +259,7 @@ const uint16_t failsafe_ppm[ PPM_ARRAY_MAX ] =
#define PPM_COMPARE OCR1A
#define PPM_COMPARE_FLAG COM1A0
#define PPM_COMPARE_ENABLE OCIE1A
#define PPM_COMPARE_FORCE_MATCH FOC1A
#define USB_DDR DDRC
#define USB_PORT PORTC
@ -312,6 +313,7 @@ void EVENT_USB_Device_Disconnect(void)
#define PPM_COMPARE OCR1B
#define PPM_COMPARE_FLAG COM1B0
#define PPM_COMPARE_ENABLE OCIE1B
#define PPM_COMPARE_FORCE_MATCH FOC1B
#else
#error NO SUPPORTED DEVICE FOUND! (ATmega16u2 / ATmega32u2 / ATmega328p)
@ -343,13 +345,8 @@ void ppm_start( void )
// Stop interrupts
cli();
#if defined (_POSITIVE_PPM_FRAME_)
// Make sure initial output state is high
PPM_PORT |= (1 << PPM_OUTPUT_PIN);
#else
// Make sure initial output state is low
PPM_PORT &= ~(1 << PPM_OUTPUT_PIN);
#endif
// Wait for output pin to settle
//_delay_us( 1 );
@ -363,6 +360,11 @@ void ppm_start( void )
// Set TIMER1 8x prescaler
TCCR1B = ( 1 << CS11 );
#if defined (_POSITIVE_PPM_FRAME_)
// Force output compare to reverse polarity
TCCR1C |= (1 << PPM_COMPARE_FORCE_MATCH);
#endif
// Enable output compare interrupt
TIMSK1 |= (1 << PPM_COMPARE_ENABLE);