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Improve BME280 code samples for negative values (#1794)

This commit is contained in:
vsky 2017-02-12 17:08:02 +01:00 committed by Marcel Stör
parent b26ed97246
commit 0349c1e004
1 changed files with 16 additions and 35 deletions
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51
docs/en/modules/bme280.md
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@ -137,27 +137,20 @@ QNH = bme280.qfe2qnh(P, alt)
print(string.format("QNH=%d.%03d", QNH/1000, QNH%1000))
H, T = bme280.humi()
if T<0 then
print(string.format("T=-%d.%02d", -T/100, -T%100))
else
print(string.format("T=%d.%02d", T/100, T%100))
end
local Tsgn = (T < 0 and -1 or 1); T = Tsgn*T
print(string.format("T=%s%d.%02d", Tsgn<0 and "-" or "", T/100, T%100))
print(string.format("humidity=%d.%03d%%", H/1000, H%1000))
D = bme280.dewpoint(H, T)
if D<0 then
print(string.format("dew_point=-%d.%02d", -D/100, -D%100))
else
print(string.format("dew_point=%d.%02d", D/100, D%100))
end
local Dsgn = (D < 0 and -1 or 1); D = Dsgn*D
print(string.format("dew_point=%s%d.%02d", Dsgn<0 and "-" or "", D/100, D%100))
-- altimeter function - calculate altitude based on current sea level pressure (QNH) and measure pressure
P = bme280.baro()
curAlt = bme280.altitude(P, QNH)
if curAlt<0 then
print(string.format("altitude=-%d.%02d", -curAlt/100, -curAlt%100))
else
print(string.format("altitude=%d.%02d", curAlt/100, curAlt%100))
end
local curAltsgn = (curAlt < 0 and -1 or 1); curAlt = curAltsgn*curAlt
print(string.format("altitude=%s%d.%02d", curAltsgn<0 and "-" or "", curAlt/100, curAlt%100))
```
Or simpler and more efficient
@ -167,29 +160,20 @@ alt=320 -- altitude of the measurement place
bme280.init(3, 4)
T, P, H, QNH = bme280.read(alt)
if T<0 then
print(string.format("T=-%d.%02d", -T/100, -T%100))
else
print(string.format("T=%d.%02d", T/100, T%100))
end
local Tsgn = (T < 0 and -1 or 1); T = Tsgn*T
print(string.format("T=%s%d.%02d", Tsgn<0 and "-" or "", T/100, T%100))
print(string.format("QFE=%d.%03d", P/1000, P%1000))
print(string.format("QNH=%d.%03d", QNH/1000, QNH%1000))
print(string.format("humidity=%d.%03d%%", H/1000, H%1000))
D = bme280.dewpoint(H, T)
if D<0 then
print(string.format("dew_point=-%d.%02d", -D/100, -D%100))
else
print(string.format("dew_point=%d.%02d", D/100, D%100))
end
local Dsgn = (D < 0 and -1 or 1); D = Dsgn*D
print(string.format("dew_point=%s%d.%02d", Dsgn<0 and "-" or "", D/100, D%100))
-- altimeter function - calculate altitude based on current sea level pressure (QNH) and measure pressure
P = bme280.baro()
curAlt = bme280.altitude(P, QNH)
if curAlt<0 then
print(string.format("altitude=-%d.%02d", -curAlt/100, -curAlt%100))
else
print(string.format("altitude=%d.%02d", curAlt/100, curAlt%100))
end
local curAltsgn = (curAlt < 0 and -1 or 1); curAlt = curAltsgn*curAlt
print(string.format("altitude=%s%d.%02d", curAltsgn<0 and "-" or "", curAlt/100, curAlt%100))
```
Use `bme280.init(sda, scl, 1, 3, 0, 3, 0, 4)` for "game mode" - Oversampling settings pressure ×4, temperature ×1, humidity ×0, sensor mode: normal mode, inactive duration = 0.5 ms, IIR filter settings filter coefficient 16.
@ -199,11 +183,8 @@ Example of readout in forced mode (asynchronous)
bme280.init(3, 4, nil, nil, nil, 0) -- initialize to sleep mode
bme280.startreadout(0, function ()
T, P = bme280.read()
if T<0 then
print(string.format("T=-%d.%02d", -T/100, -T%100))
else
print(string.format("T=%d.%02d", T/100, T%100))
end
local Tsgn = (T < 0 and -1 or 1); T = Tsgn*T
print(string.format("T=%s%d.%02d", Tsgn<0 and "-" or "", T/100, T%100))
end)
```