Simple explanation of channels

Question

Hello people,

I am having an already existent Quartus II project with my custom code and I want to implement a floating point control structure with DSP builder and use it inside the custom project as a black box, trigger its execution and takes its outputs.

My custom project has some ADC interface logic (SPI protocol for example) that works on 100kHz (so Sample rate of 100kHz) and a system clock of 150MHz (50MHz input to the Cyclone IV and with a PLL stepped up to 150MHz).

The control structure will accept the ADC integer data as input (something like 10 variables) and it will produce 3 to 4 integer outputs.

I havent understood the concept of channels though. In order to pass the input variables to the block do I have to use the channel feature or can I just create 10 data inputs?

P.S. My clock-to-sample rate is 150MHz/100kHz=1500 so i also prefer to use folding(resource sharing) because my FPGA is not that big.

Thanks!

altera_forum · Answer

in general a channel in DSPBuilder means a specific sequence of samples that represent a signal. I believe the folding option = floor[Fclk/(Fs per channel * number of channels)]

altera_forum · Answer

Hey thanks for the answer.  But why would somebody want to represent one signal in multiple channels?

altera_forum · Answer

who wants to do that. one signal is one channel. one adc output is one channel to begin with but you may have a composite adc signal e.g. carrying 5 cdma carriers separated in frequency. If you then separate them into 5 cdma signals then each is one channel.

altera_forum · Answer

Hmmm. By reading a bit of the DSP Builder documentation I suspect that channels are samples that are fed through the same arithmetic processes but are individual to each other. For example I need the control system for a power electonics application and for this I need some current and voltage samples to be fed into some control structure. Since the current and voltage are combined inside the arithmetic process I cannot combine them into one datapath as two channels. Is it so?

altera_forum · Answer

--- Quote Start ---

Hmmm. By reading a bit of the DSP Builder documentation I suspect that channels are samples that are fed through the same arithmetic processes but are individual to each other. For example I need the control system for a power electonics application and for this I need some current and voltage samples to be fed into some control structure. Since the current and voltage are combined inside the arithmetic process I cannot combine them datapath as two channels. Is it so?

--- Quote End ---

if current signal is separate from voltage signals then in theory it is two information channels. When it comes to processing then if you are targeting same identical processing on each then you can use two channel settings. but if at some point you need to process them together then naturally it is one channel from processing perspective.

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Simple explanation of channels

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