DHT22 Causing Upload to Fail

Other Hardware Sensors
1

Hi all. In trying to make a little humidity control device, I have an Arduino Uno hooked up to an LCD keypad, Fan, RTC, SD card breakout board, and finally DHT 22 temperature/humidity sensor.

Code uploads and works fine when I have everything but the DHT22 power line connected, but when I try to upload with the DHT22 connected to 5v, I get the following error:

avrdude: stk500_set_extended_parms(): protocol error, expect=0x14, resp=0x00
avrdude: stk500_initialize(): failed
avrdude: initialization failed, rc=-1
         Double check connections and try again, or use -F to override
         this check.

avrdude: stk500_disable(): protocol error, expect=0x14, resp=0x00
Problem uploading to board.  See http://www.arduino.cc/en/Guide/Troubleshooting#upload for suggestions.

Anyone know what this means or how to fix it? Thanks!

2

Could be that all things together take too much current?
Do you have a Digital MultiMeter to check?

Or to which pin is the DHT22 powerline connected?
Or is it directly connected to 5V?

Have you tried only the DHT22 with a test sketch?
TO check it is not broken?

3

The current thing was my best guess too but I thought the DHT's current draw would be too small to have such a big effect.

I had tested the sensor itself with a test sketch but after your suggestion tried the same sketch with only the DHT connected and got the same error so I switched the signal pin and it worked.

Thanks for making me think robtillaart!

I guess you can't use pin 0 for the DHT signal? Do you know why that is? Is there a way to override whatever prevents this? I need to use every pin available for my project so very curious to figure that out.

4

Pin 0 is the serial RX (receive data) pin, that's whats goofing up your upload, do you have an unused analog (A0 - A5 pin)?

5

I do! and so I tried that out but then realized that my one unused analog pin A4 is somehow connected to my RTC which is hooked up to the Uno's SDA and SCL pins. So it uploaded, but my RTC stopped working (showed 2165/165/165 as the date).

Don't know how to get around this

6

Look up the default use of the pins of your Arduino.

Pin 0 and 1 are Serial.
Pin A4 and A5 are for I2C.

That still leaves another 18 or so pins available. You use them all?

Other devices (I've had LEDs connected to those without issues) may not affect TX/RX pins, so swapping out connections may also help.