rx stick calibration

[alll]

Happy new year!

Idea is to avoid setting the endpoints of transmitter to "1000" ... "2000" in the gui.
We “assume” then throttle(1000)-pitch(1500)=500 msec, read the real values, make the ratio...

To do so, a transmitter calibration has to be done once.
During calibration, throttle at low position (=1000), yaw, pitch and elevator at center (=1500). The calibration procedure reads the rx values, calculates the offset and stores the rx ratio. Later, this ratio is multiplied with the read rx-values.
This way, in code we can assume 1000-2000 rx inputs.

Manu

[Hamburger]

probably not good. For experiment make up a number out of [1000;2000] and then try to move any of your tx sticks until the corresponding value in the MWii gui is equal to that number.
Soem things to consider:
- you want maximum resolution (distinguishable steps) on the tx-rx side; if your tx emits only say [1300;1700] and your modified software in MWii would map that to the [1000;2000] range you would have even less resolution than you have nowadays.
- you must not exceed this [1000;2000] range, otherwise it may corrupt the joint wireless signal, making separate channels no longer distinguishable; then you have a failsafe condition.

I agree it is tedious to setup properly; but with typical limited hardware it is worth it.

[alll]

Thanks for your input,

We assume the transmitter as a reference for rx signal lengths. This suppose that transmitter has all values by default, so we will "never" exceed the "1000" msec range!
So for example throttle reads 1020, pitch/roll/yaw averaged 1530 => diff=510 (if the difference between throttle and p/r/y not near +-500, or throttle +-1000, you have a problem with your transmitter anyway!).

Calibration :
check throttle = "1000" (+-20)
check thr-avg(r/p/y)="500" (+-20)
ratio ("500"/(1530-1020))
rx p/r/y = rxvalue*ratio-"500"
rx offsets thr = rxvalue*ratio-"1000"


If mwii does not support signals longer then 2000 msec, a proper rx calibration would be a nice to have.
* power up board,
* wait for rx inputs 1000-2000 (+-20) for all channels (loop until no stick movement and all channels +-1000 range),
* calibrate rx
* ready to arm

manu
PS: taking the rx as a clock reference, we could overclock the mcu, and multiply all read rx timings by the ratio..., your radio is the "clock reference"

[alll]

I really want to get my esc's calibrated correctly BASED ON THROTTLE STICK POSITION and not on "real" timings !!!...

If in the gui i see for throttle min:1065 and max:2003
Then i set ?:

Code: Select all

    #define MINTHROTTLE 1000
    #define MAXTHROTTLE 1997
    #define MINCOMMAND  935

And apparently the rx setup in gui you are suppose NEVER to get lower then 1000 or higher then 2000!

Sorry to say, but it is really confusing, i really need to have a better understanding of the code logic (main loop).

manu

[sorg]

Happy new year!

Idea is to avoid setting the endpoints of transmitter to "1000" ... "2000" in the gui.
We “assume” then throttle(1000)-pitch(1500)=500 msec, read the real values, make the ratio...

To do so, a transmitter calibration has to be done once.
During calibration, throttle at low position (=1000), yaw, pitch and elevator at center (=1500). The calibration procedure reads the rx values, calculates the offset and stores the rx ratio. Later, this ratio is multiplied with the read rx-values.
This way, in code we can assume 1000-2000 rx inputs.

Manu

I support this idea.

I have a crappy transmitter with some channels shifted (fo example throttle cover a range from 900 to 1850... even with maximum trimming...). That means that i have a dead zone at low throttle, and i can't reach maximum throttle. That would be good to be able to compensate that on multiwii side.

[Mis]

This is not standard behaviour. Do it yourself in Your private code.
In RX.ino in function "uint16_t readRawRC(uint8_t chan)" add few lines just lines before "return data; // We return..."

Code: Select all

if(chan == THROTTLE) data += 125;      // add 125 to throttle
if(chan == ROLL)     data -= 25;       // substract 25 from ROLL channel

ect, ect.