3 replies to this topic

[tridy]

Hi.
I am trying to read the signal from a RF 433.92 receiver module via AnalogInput (A0) and I am looking at Arduino library that has the implementation of sending RF signal. There it writes the data at the rate of 250 microseconds. The documentation says Arduino can read at the rate of 100 microseconds.

My question is if Netduino can read via AnalogInput at the rate of 100 microseconds?

Thanks.

[tridy]

Ok, I did not do my homework.

 

http://forums.netdui...og-io/#entry249

http://blog.devmobil...put-read-rates/

 

so, using .net framework (non-realtime) slows down analog readings a bit and when talking in terms of 250 microseconds, it is not enough. Here is an example where the values from the same RF 433.92 module were read using oscilloscope and then using Netduino:

 

 rf_readings.png   213.5KB   1 downloads

 

and as you can see Netduino does not get enough samples to create the same picture.

 

So, I need a lower-level C++ implementation of the reading and writing functionality. I will try doing it in Arduino UNO and then hopefully be able to switch to a small Arduino Mini and connect it to Netduino from there.

 

and I was thinking either it's me reading the data the wrong way or Excel that does not have the correct chart type for Netduino generated data .

 

 

[KiwiDev]

Hi Tridy,

 

Could you tell us a bit more about your application (what you are trying to achieve) and some information about the modules you are using?

 

A period of 250 Microseconds means a frequency of 4000Hz which a Netduino should be able to read (assuming you are not doing "too much" with the measurement).

 

Are you trying to recover a bitstream, then Nyquist-Shannon means you need to sample at a 2x the frequency..

 

If the values could be treated as "digital" then an InterruptPort based approach might be possible.

 

@KiwiBryn

blog.devmobile.co.nz

[tridy]

Hi.

I am basically implementing RF 433.92 remote control repeater and temperature/humidity sensor readers, without using any additional libraries. It is reading the pin when it is in the HIGH and LOW states if we talk Arduino language. Then to repeat, setting HIGH and LOW on the pin for certain periods of time. When setting values on the pins, the minimum timing used there between the changes is 250 microseconds. When reading the values, [I haven't really measured it, but] according to documentation, it can do 100 microseconds, which is sufficient for what I do. From what I understand, it is the real-lime readings, which is not achievable by Netduino that matters a lot (but it might be coming soon ???).

 

regards