Hey guys ! As long as we are talking about serial interface, I am having a strange problem with my netduino + I am using serial to send data back and forth from a PC (very standard), using sparkfuns FTDI board. The netduino can receive data no problem (test was to turn on/off the on board LED on command) however it cannot send any data to the PC. I am sure I have the wiring right, I am sure I have the Jumper on the FTDI board set to 3.3 V (even measured voltage with meter). I was so frustrated that I had the netduino send data on interrupt from SW and scoped Tx ( on COM1 thats D1) ... There was nothing on the scope ... D1 is dead !! It works fine as an Inputport/OutputPort/InterruptPort but no serial. (same case for COM2 ie: D3) Am I missing something ? Do I need to enable something ? Please advise ANY help is appreciated !!! Even if its a confirmation that my Netduino+ is broken and needs to be replaced, I am going nuts here !!! Thanks alot !!! Ahmed

My interest is in learning how to design and write VHDL code. There are many quadrature encoder routines available for download on the web, but grabbing code which someone else has written does not teach you very much.

Well, I understand the concept and I dont have a problem writing the code for say a 2.4GHz processor x86 with a 4 GBs of ram sampling time of around 1e-6 second easily, the problem I had over here was using this high resolution encoder with a netduino thats all. Just to put things in perspective, if the shaft is rotating at 3 revs/second (180 rpm which is not much )thats 1200*3 = 3600 interrupts/second. I just need help on generating an efficient enough code for the netduino to be able to handle all that along side of some computation thats all. Like I said I am just not used to micro-framework.

Hey guys !
I am new here, first post ! I am a meng, so code and electronics are not really my strengths, but I know a few things from research and several projects. I am using a Netduino Plus for this project. It has some PID control and DAQ.

The Problem

I am currently stuck with a 1200 dots per rev shaft encoder. Its a quadrature encoder, giving a phase A and B. I managed to build a decoding circuit (flip-flops,AND & NOR gates) and now I have 2 wires that give pulses for each direction of rotation. I do NOT have a dedicated counter so I am using the pulses to interrupt on GPIO of the netduino (is that wrong? ). Interrupt ports work fine ( position ++; ) however, I need the netduino to be constantly monitoring the process set value through the ADC. That means a while(true) loop and here is where the interrupts from the encoder stop working because the processor is stuck in the loop. If I break the loop, interrupts work fine, but it is no longer monitoring the set value.
I also run into ALOT of out of memory exceptions ( without even adding the print to console to start graphing), specially when the motor starts going fast ( crashes asa duty cycle goes above 45).

Options I tried to consider with no luck:

1) send the the required set values through USB instead of an Analog signal

2) send the values over TCP :
Would love to, as it adds wireless control feature, easily interface with matlab DAQ and simulink. However, I need alot of help coding that (code examples appreciated). Also I was advised that this will consume memory very fast.


I think my major problem is that I am used to matlabs xpc, so memory and sampling times were almost never an issue, plus multi tasking and threading / multi core support was also available so monitoring multiple variables and updating multiple varriables at the same time was not an issue either.

Please help, any advice is much appreciated and welcomed !!
Thanks in advance !!