#57 PPMOut bugs

[dvdouden]

"Hi,
first of all thanks for the code. As i intend to build an RC Transmitter myself, this is exactly what i was looking for.
I tried the example code for PPM_out on an arduino Nano. As it did not work as expected, i looked at the library's PPMout.cpp code.
I came across the recomendation of pin 9 and 10 as output, as these can be configured to toggle automaticly on an output compare event. The problem i found is, pin 10 is OC1B in AVR-Terms. You configure it to toggle on an output compare event, but always use OCR1A to generate the event. If you wan't to use the toggle mode of pin 10, you will have to use OCR1B instead...
... or did i miss something ?

Furthermore the m_port member of PPMout-class is uninitialized, which might lead to an unwanted modification of some random port in the isr-subroutine when using pin 9 or 10.

Thanks again, and keep up the good work!
Sven"

[dvdouden]

"Your welcome...
... may i add another fix then ? The computation of
define PPMOUT_WORK_SIZE(channels) ((channels) + (((channels) + 1) * 4))

should be
define PPMOUT_WORK_SIZE(channels) ((channels)*2 + (((channels) + 1) * 4))

or to make it more intuitive
define PPMOUT_WORK_SIZE(channels) (((channels) + ((channels) + 1) * 2) * sizeof(uint16_t))

as all the data you're gonna store in those fields is uint16_t!

After fixing this, my PWM output is finally stable! Before it flickered an then crashed, i just wasn't sure if it was my code or yours. Your example might have worked because there were no globals after the definition of g_work, so nobody got hurt.

Sven"

[dvdouden]

Also add support for fixed frame width

https://sourceforge.net/p/arduinorclib/discussion/features/thread/de1323b9/