ADS1256EVM Throughput: SYNC/PWDN Pin vs SPI SYNC/WAKEUP cmd

Daniel Vamos

Greetings!

I would like to cycle through ADS1256EVM AI channels (500SPS) as fast as possible. Base on the datasheet Page 21/ Table 14. With 500 SPS settings the max achievable throughput is 456Hz with SPI synchronization. In my solution the result is more or less equal to the values listed in the Table 14.

However, when I am not using SPI Synch/Wakeup commands for synchronization; only SYNC/PWDN pin tied to High (No toggling) in EVM and update the AI channel index when DRDY is in low state. I can achieve exactly the 500Hz rate.

If the precise sampling rate is achievable with the second method, why is the first one is recommended? (And not mentioned the 2nd one?)

Could someone explain this?

LogicData result is attachedThroughput Test.rar

over 10 years ago

0 Christopher Hall over 10 years ago

TI__Mastermind 44680 points

Hi Daniel,

Here's a quick answer for you before lunch...

Only the first conversion result is delayed! Consecutive conversions (of the same channel) should occur at the 500 SPS data rate.

In the 456 SPS case, you must be multiplexing between channels (i.e. restarting the conversion each time)
In the 500 SPS case, you're likely reading from the same channel each time.

Best Regards,
Chris

0 Daniel Vamos over 10 years ago in reply to Christopher Hall

Genius 3950 points

Thanks! Got It :)

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ADS1256EVM Throughput: SYNC/PWDN Pin vs SPI SYNC/WAKEUP cmd