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Update drv_pwm.c #153

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Update drv_pwm.c #153

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544bb17
Update drv_pwm.c
Crashpilot1000 Jul 31, 2014
91761fc
Update drv_pwm.c
Crashpilot1000 Jul 31, 2014
5a9468c
Update drv_pwm.c
Crashpilot1000 Aug 1, 2014
7654af3
Update drv_pwm.c
Crashpilot1000 Aug 2, 2014
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37 changes: 30 additions & 7 deletions src/drv_pwm.c
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Original file line number Diff line number Diff line change
Expand Up @@ -281,19 +281,42 @@ static void failsafeCheck(uint8_t channel, uint16_t pulse)
}
}

// Contains detection & fix for the "8 channels in 18ms Frsky problem" see:
// http://diydrones.com/profiles/blogs/why-frsky-cppm-signal-is-so-disappointing
// http://forums.openpilot.org/topic/16146-cc3d-with-frsky-8-channels-in-cppm-mode/
// Tested on: Frsky D8R-II and Frsky D4FR
static void ppmCallback(uint8_t port, uint16_t capture)
{
(void)port;
uint16_t diff;
static uint16_t now;
uint16_t newval = capture;
static uint16_t last = 0;
static uint16_t frametime = 0;
static uint8_t chan = 0;
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this is here from beginning, but if youre updating this part of code might as well make chan as int.

static uint8_t frsky_errcnt = 0;
static bool frsky_18patch = false;
uint16_t diff = newval - last;
bool sync = diff > 2700; // rcgroups.com/forums/showpost.php?p=21996147&postcount=3960 "So, if you use 2.5ms or higher as being the reset for the PPM stream start, you will be fine. I use 2.7ms just to be safe."
last = newval;

if(frsky_18patch) {
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spacing between if and (

sync |= chan == 8; // FrSky 18ms Fix, force sync after 8 channels
} else {
frametime += diff;
}

last = now;
now = capture;
diff = now - last;

if (diff > 2700) { // Per http://www.rcgroups.com/forums/showpost.php?p=21996147&postcount=3960 "So, if you use 2.5ms or higher as being the reset for the PPM stream start, you will be fine. I use 2.7ms just to be safe."
if (sync) {
if(!frsky_18patch) {
if(frametime < 18300 && chan == 8) {
frsky_errcnt++;
} else {
frsky_errcnt = 0;
}
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no need for braces for single line if () conditions

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I thought BF wants it that way because here: https://github.com/multiwii/baseflight/blob/master/src/mw.c#L108

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left overs of original code.
coding styles doc says otherwise.
that's usually authoritative reference.
On Jul 31, 2014 5:54 PM, "Crashpilot1000" [email protected] wrote:

In src/drv_pwm.c:

  • last = now;
  • now = capture;

- diff = now - last;

I thought BF wants it that way because here:
https://github.com/multiwii/baseflight/blob/master/src/mw.c#L108

—
Reply to this email directly or view it on GitHub
https://github.com/multiwii/baseflight/pull/153/files#r15631816.

if(frsky_errcnt == 30) {
frsky_18patch = true; // Condition must be true 30 times in a row before we enable the FrSky fix
} else {
frametime = 0;
}
}
chan = 0;
} else {
if (diff > PULSE_MIN && diff < PULSE_MAX && chan < MAX_INPUTS) { // 750 to 2250 ms is our 'valid' channel range
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