October 17, 2011
about 8 months ago
I had a look at the Matrix Backpack Controller firmware, but it does not seem to support the % command. Am I right? I’m trying to have some text scroll on two display, but my code makes the display flicker. The reason is that every time I write to the display, what was in there shifts left, which generate the flickering. Any suggestions?
about 3 years ago
Thank you PharoahsMummy for your kind support. I think I sorted this out. It was not how long I was pulling down the data pin. It was the fact that my PIC was starting to ask for data too early. What happens is that the RHT03 not only do not respond to that inquiry, but will never respond in the future to any inquiry. The only way is to reset it, i.e. cut the power and the re-establish it. Instead if the PIC waits a couple of seconds (may be more, I’ve not measured exactly), then the RHT03 works beautifully. The data sheet mention this “When power is supplied to sensor, don’t send any instruction to the sensor
within one second to pass unstable status.”. What it does not mention is that, if you do, the RHT03 will never respond again. Bitchy device :-)
Well understood, but the 40us wait is to release control to the RHT03. With the oscilloscope, after I have have put the pin 2 to ground for 100ms and pulled it back up, I should see some set of high-low pulses… while instead I see nothing, but a high signal. Do you agree, there is something wrong or there are other things I should be checking? Thanks you very much for your council.
Thank you PharoahsMummy. I don’t have a digital analyzer, but I do have an oscilloscope that triggers on the rising edge of the signal. I tried setting the data pin low for over 100ms to allow the RHT03 to recognize the start signal, but after the rising edge I don’t see any response. The signal remains high. Does the low signal has to be exactly 18ms and if it is more or less won’t work? This is not what the doc says, but I can try as soon as I find a little bit of time for my hobby :-)
Thanks a bunch.
I got two of these few days ago. During the weekend I wanted to see how it worked. Connected pin 1 to 5V, pin 2 with 1K resistor to 5V, pin 3 and 4 to GND. Connected an oscilloscope to pin 2 and briefly brought pin2 to ground. I can see the rising edge, but just a flat solid 5V (i.e. high bit). I tried to pilot it using a digital line from a Flyport, but got same results. I tried to use the second RHT03 that I got, same behavior. Looks like they are not working. Any suggestions on what I’m doing wrong or how can I check if they are working? Thanks a lot.
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