drivers: lora: LDRO and bandwith additions #100977
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Okay was able to cross check using force-ldro, sx1278, and LLCC68, as expected they cant talk to each others when only one is forced into ldro, assuming the maths for the 16 ms is correct everything should be good. |
Add missing values and replace arbitrary BW enum with actual value Signed-off-by: Camille BAUD <mail@massdriver.space>
VynDragon
changed the title
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Well and went and checked the possible edge results for the maths with this little program: #include <stdio.h>
int main()
{
for (int sf = 5; sf < 12; sf++) {
for (float bw = 1000.0; bw > 5.0 ; bw/=2.0) {
int t = (1 << sf) / (int)(bw);
if (t > 10 && t < 22) {
printf("bw: %f (%d), sf: %d, t:%d\n", bw, (int)(bw), sf, t);
}
}
}
}Gets all the same result as the calculator so all good. |
Enable LDRO when it should be enabled Signed-off-by: Camille BAUD <mail@massdriver.space>
Allows Enabling LDRO all the time via DTS Signed-off-by: Camille BAUD <mail@massdriver.space>
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| BW_500_KHZ = 500, /**< 500 kHz */ | ||
| BW_800_KHZ = 800, /**< 812 kHz */ | ||
| BW_1000_KHZ = 1000, /**< 1000 kHz */ | ||
| BW_1600_KHZ = 1600, /**< 1625 kHz */ |
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With the extra bandwidth options, whats the behaviour when an invalid bandwidth for the modem is selected? Does LBM reject it?
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I think it does (I think i tried it once? but LBM doesnt know about LLCC68 for example sooo), but it doesn't matter, I was working on this to solve those kind of possible issues: #100989
3 participants
Add missing bandwidths, set enum to be value in khz, add missing sf
use enum value in khz to calculate approximate symbol time
use symbol time to determine if ldro should be enabled
add option to always enable ldro regardless of symbol time
symbol time checked against lora calculator https://www.semtech.com/design-support/lora-calculator, formula is good enough to match without using floats.
See any modem datasheet for 16ms/16.38ms times and the symbol rate / symbol time formulas