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reading from adc with 1mhz speed

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hamid.abbaszadeh

hamid.abbaszadeh

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i am working on xmega128a1 with an external adc that has more than 1mhz speed.
i want to read from adc and show data on lcd. but during to show it lose adc data.
also i use dma and save data and then show them.but for save data with this speed need to big memory and idont want to use external memory.please help me
 

At this rate, you should necessarily compress the data to fit at the LCD viewable area.
The most intuitive way to do that could be by taking the average value, or even interleaving samples.
 

i wanted to take average but this claculating use clock time and we lose some data
 

Hi,

Please be more descriptive.

1 mHz or 1 MHz? It's different if you mean milli or mega.

Do you want to display a number or do you want to display a graph, like a scope?
What update rate do you want for your display?

*****
I assume you mean 1MHz.. may I sak, why you don't use a slower conversion rate?

Tell us about your application. What analog input signal, where does it come from, is waveform or frequency of interest?

Klaus
 

hi dear ofcourse 1Mhz-whats difference between gragh and number-i want both-but graph is better-accuracy is very important for me so i need 1Mhz rate-analog signal is near 200khz with noise-
 

Hi,

For graph you need to calculate hundreds of different points and their position. This needs a lot of processing power.

For displaying a number -let's say every 300ms- you need low processing power.
Also you say averaging...If you just average the ADC values, you should consider using an analog low pass filter (doing some averaging for you - and use a much smaller sample rate. The result will be the same.

A higher sampling rate does not increase accuracy, especially not when you average the values.

Klaus
 

hamid.abbaszadeh said:
i need 1Mhz rate-analog signal is near 200khz with noise-
Click to expand...

If the signal bandwidth is 200KHz, a sample rate 4x of this ( 800KHz ) instead of 1MHz could save a lot of the core processing, and in addition would even exhibit a slightly better low pass filtering performance for the acquired signal, and noise.
 

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