ESP8266 Community Forum

- Sat Jan 03, 2015 3:00 pm #6190 No, this is just a missunderstanding.
I have 1 of the very first ESP-01 modules and this one has actualy 2 unconnected pins - GPIO0 and GPIO2 are not connected.
I just wanted to make sure you are not one of the unlucky first explorers with such a module
Should your LED work, you have the "correct" ESP-01.

- Sat Jan 03, 2015 4:17 pm #6195 Got it working. Timing was so tight it almost doesn't work. Good luck, and I hope someone can clean it up a bit. Just be cautious of modifying the acquisition loop.

Code: Select all--Works for DHT11 on ESP-07 (version w/16pins)
--Only 20141219 firmware tested.

--Data stream acquisition timing is critical. There's
--barely enough speed to work with to make this happen.
--Pre-allocate vars used in loop.
bitStream = {}
for j = 1, 40, 1 do
     bitStream[j]=0
end
bitlength=0

pin  = 4;
gpio.mode(pin, gpio.OUTPUT)
gpio.write(pin, gpio.LOW)
tmr.delay(20000)
--Use Markus Gritsch trick to speed up read/write on GPIO
gpio_read=gpio.read
gpio_write=gpio.write

gpio.mode(pin, gpio.INPUT)

--bus will always let up eventually, don't bother with timeout
while (gpio_read(pin)==0 ) do end

c=0
while (gpio_read(pin)==1 and c<100) do c=c+1 end

--bus will always let up eventually, don't bother with timeout
while (gpio_read(pin)==0 ) do end

c=0
while (gpio_read(pin)==1 and c<100) do c=c+1 end

--acquisition loop
for j = 1, 40, 1 do
     while (gpio_read(pin)==1 and bitlength<10 ) do
          bitlength=bitlength+1
     end
     bitStream[j]=bitlength
     bitlength=0
     --bus will always let up eventually, don't bother with timeout
     while (gpio_read(pin)==0) do end
end

--DHT data acquired, process.

Humidity = 0
HumidityDec=0
Temperature = 0
TemperatureDec=0
Checksum = 0
ChecksumTest=0

for i = 1, 8, 1 do
     if (bitStream[i+0] > 2) then
          Humidity = Humidity+2^(8-i)
     end
end
for i = 1, 8, 1 do
     if (bitStream[i+8] > 2) then
          HumidityDec = HumidityDec+2^(8-i)
     end
end
for i = 1, 8, 1 do
     if (bitStream[i+16] > 2) then
          Temperature = Temperature+2^(8-i)
     end
end
for i = 1, 8, 1 do
     if (bitStream[i+24] > 2) then
          TemperatureDec = TemperatureDec+2^(8-i)
     end
end
for i = 1, 8, 1 do
     if (bitStream[i+32] > 2) then
          Checksum = Checksum+2^(8-i)
     end
end
ChecksumTest=(Humidity+HumidityDec+Temperature+TemperatureDec) % 0xFF

print ("Temperature: "..Temperature.."."..TemperatureDec)
print ("Humidity: "..Humidity.."."..HumidityDec)
print ("ChecksumReceived: "..Checksum)
print ("ChecksumTest: "..ChecksumTest)


screenshot.38.png (1.56 KiB) Viewed 4514 times

Last edited by Pigs Fly on Sat Jan 03, 2015 4:21 pm, edited 1 time in total.

- Sat Jan 03, 2015 4:20 pm #6196 Thanks for that, as soon as my DHT arrive, I'll test the code of yours.

- Sat Jan 03, 2015 6:13 pm #6201 It's encouraging that so far the code has worked on 10 different DHT11 modules and three ESP modules. Apparently there's little variation because they all work. I have DHT22's on order - will someone port/test this with a DHT22 if you have one? Looks like the same acquisition routine, just different processing of the data,