Re: [ts-7000] TS-ADC24 max sample rate?

[mike ingle <>]

You are seeing the result of linux being a multi-tasking OS.  Your application runs for xxx cycles the gets switched from to some other task.  You need to use a device driver and interrupts to get the data off the adc card before the buffer overflows. 

 

ftp://ftp.embeddedarm.com/pc104-peripherals/ts-adc24/   has .lib files I am not sure where the expected .o files and the api description is.  You should contact technologics.

 

 

On Mon, Sep 7, 2009 at 9:44 AM, bburtan65 <> wrote:

 

Okay, so Technologic states several times in the literature for the ADC24 board that it has a 1Msps sample rate. However, in my experience so far just sampling the minimum four channels, the absolute best I seem to be able to do is 100ksps before the buffer overflows and the ADC stops.

Here is a code snippet:

adc = (ADC_Data_Type *)mmap(0, getpagesize(), PROT_READ|PROT_WRITE, MAP_SHARED, fd, IO_BASE);
adc += (ADC_OFFSET)/sizeof(ADC_Data_Type);
adc_channel_address = adc + 0x4; // For slightly faster access to the channel register
adc_data_address = adc + 0x5; // For slightly faster access to the sample data

ADC(2) = 0; // Reset the ADC
configuration = configuration | diff_mode;
if (diff_mode == kDiff_Mode_Single_Ended)
configuration = configuration | kDiff_Mode_Single_Ended_8bit;
configuration = configuration | input_range;
configuration = configuration | ((num_channel_blocks-1) << 1);
num_channels = num_channel_blocks * 4;
ADC(2) = configuration | 1;

The main loop is here:

do {
current_channel = ((*(adc_channel_address)) >> 1) & 0x1f;
sample_data = (*(adc_data_address));
} while (current_channel != 0);

adcValue = (sample_data & 0x07ff) + (!(sample_data & 0x800)*0x800);

If I do nothing else but the above do/while and adcValue lines, 100ksps is about the maximum. If I'm running other threads that slows way down. So why can I never get 1Msps?

__._,_.___

Your email settings: Individual Email|Traditional
Change settings via the Web (Yahoo! ID required)
Change settings via email: =Email Delivery: Digest | m("yahoogroups.com?subject","ts-7000-fullfeatured");=Change Delivery Format: Fully Featured">Switch to Fully Featured
Visit Your Group | Yahoo! Groups Terms of Use | =Unsubscribe

__,_._,___