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Turn some variables to local 

ake some adjustments because of the optimization using local variables
This commit is contained in:
Javier Yáñez 2015-01-25 20:13:07 +01:00
parent 3ede2de2ea
commit 71dd55ba45
1 changed files with 12 additions and 13 deletions
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25
lua_modules/dht22/dht22.lua
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@ -13,23 +13,22 @@ _G[moduleName] = M
local humidity local humidity
local temperature local temperature
local checksum
local checksumTest
function M.read(pin) function M.read(pin)
local checksum
local checksumTest
humidity = 0 humidity = 0
temperature = 0 temperature = 0
checksum = 0 checksum = 0
-- Use Markus Gritsch trick to speed up read/write on GPIO -- Use Markus Gritsch trick to speed up read/write on GPIO
gpio_read = gpio.read local gpio_read = gpio.read
gpio_write = gpio.write
bitStream = {} local bitStream = {}
for j = 1, 40, 1 do for j = 1, 40, 1 do
bitStream[j] = 0 bitStream[j] = 0
end end
bitlength = 0 local bitlength = 0
-- Step 1: send out start signal to DHT22 -- Step 1: send out start signal to DHT22
gpio.mode(pin, gpio.OUTPUT) gpio.mode(pin, gpio.OUTPUT)
@ -43,13 +42,13 @@ function M.read(pin)
-- Step 2: DHT22 send response signal -- Step 2: DHT22 send response signal
-- bus will always let up eventually, don't bother with timeout -- bus will always let up eventually, don't bother with timeout
while (gpio_read(pin) == 0 ) do end while (gpio_read(pin) == 0 ) do end
c=0 local c=0
while (gpio_read(pin) == 1 and c < 100) do c = c + 1 end while (gpio_read(pin) == 1 and c < 500) do c = c + 1 end
-- bus will always let up eventually, don't bother with timeout -- bus will always let up eventually, don't bother with timeout
while (gpio_read(pin) == 0 ) do end while (gpio_read(pin) == 0 ) do end
c=0 c=0
while (gpio_read(pin) == 1 and c < 100) do c = c + 1 end while (gpio_read(pin) == 1 and c < 500) do c = c + 1 end
-- Step 3: DHT22 send data -- Step 3: DHT22 send data
for j = 1, 40, 1 do for j = 1, 40, 1 do
while (gpio_read(pin) == 1 and bitlength < 10 ) do while (gpio_read(pin) == 1 and bitlength < 10 ) do
@ -63,17 +62,17 @@ function M.read(pin)
--DHT data acquired, process. --DHT data acquired, process.
for i = 1, 16, 1 do for i = 1, 16, 1 do
if (bitStream[i + 0] > 2) then if (bitStream[i] > 4) then
humidity = humidity + 2 ^ (16 - i) humidity = humidity + 2 ^ (16 - i)
end end
end end
for i = 1, 16, 1 do for i = 1, 16, 1 do
if (bitStream[i + 16] > 2) then if (bitStream[i + 16] > 4) then
temperature = temperature + 2 ^ (16 - i) temperature = temperature + 2 ^ (16 - i)
end end
end end
for i = 1, 8, 1 do for i = 1, 8, 1 do
if (bitStream[i + 32] > 2) then if (bitStream[i + 32] > 4) then
checksum = checksum + 2 ^ (8 - i) checksum = checksum + 2 ^ (8 - i)
end end
end end