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analog-io/si7020_fixed.lua

Created April 10, 2015 15:55
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Fixed point Si7020 Math
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si7020_fixed.lua
local rh = read_reg(0x40,0xE5,true)
local t = read_reg(0x40,0xE0,false)
rh = string.byte(rh,1)*256+string.byte(rh,2)
t = string.byte(t,1)*256+string.byte(t,2)
t=(17572*t)/65536-4685
t=tostring(t*18+32000)
rh=tostring(rh*12500/65536-600)
t=t:sub(1,t:len()-3).."."..t:sub(t:len()-2,t:len())
rh=rh:sub(1,rh:len()-2).."."..rh:sub(rh:len()-1,rh:len())
print(t.." : "..rh)
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