Howdy,
I recently found a pretty cool site, Circuito, which, according to the site, is 'a circuit design app for makers.' You basically pick the parts and the app wires it for you. When I was playing around with it, I added a DHT22, RTC, and SD Module to see what it would do. The main difference I noticed between the circuito diagram and the way my project is set up, is that it has pullup resistors between the VCC and Data pins on the DHT22 and the SD Module.
It says to use a 330 ohm Resistor with the SD module, which I have... But that's the only value resistor I have atm. It also says to use a 10K ohm Resistor with the DHT22, which I don't have. I talked to someone on the Hackaday Google plug group that said 'the DHT libraries use the uno's internal 20k pull-up and those should be fine, but if you find yourself having random communication issues, you may have to add external ones.'
I'm occasionally getting 'nan' for the first reading on my data logger, would this be a result of not using an external pullup? I have some 330 ohm for the SD Module, I think I'll add one to my project and see if it doesn't help with the 'nan' I keep getting.
Any help is appreciated, have a good one, y'all!!!
If you get "nan" on the first reading but good readings after that, then it can't be the pull-ups. Just a timing thing. Try putting a delay(1000); in setup();.
That's not a pull up resistor. A pull up resistor goes to the +ve supply rail.
You need to give full details of all the hardware you have, vague phrases like "SD card module"
are no use when there are many many different ones out there, the details always are crucial.
If the SDcard module doesn't have level conversion on-board, then you must never connect
it directly to a 5V Arduino, this could fry every SDcard you plug into it.
I realized that after I had already posted it. But the 10K is a pullup? I'm still learning, it's alot to take in lol
MarkT:
You need to give full details of all the hardware you have, vague phrases like "SD card module"
are no use when there are many many different ones out there, the details always are crucial.
If the SDcard module doesn't have level conversion on-board, then you must never connect
it directly to a 5V Arduino, this could fry every SDcard you plug into it.
I couldn't find any specifics for the SD module I have, but it's THIS ONE HERE
