The low power 2.7V version of the chip I have specifies a maximum of 75Ksps with a 1.2MHz clock, however higher voltage versions of the chip support up to 200Ksps with a 3Mhz clock.
After I posted the 75Ksps v2.0 of the object last night, I experimented… and I was able to significantly exceed the specifications of my low voltage chip! This probably means reduced lifetime for it, and some loss of accuracy, but … I wanted the speed!
On the Parallax Propeller forum, bambino asked why I was not running at 200ksps… and given that I significantly exceeded that speed in some experiments, also given other people may also want to run at 200ksps, I re-wrote the assembly driver for an exact 200ksps sampling rate at 12 bits per sample. As my driver allows you to set the precision at which sampling will occur, this actually gives a nice range of sampling rates, so you can trade off accuracy for speed.
The following rates are available:
- 200,000 samples/sec @ 12 bits
- 222,000 samples/sec @ 11 bits
- 238,095 samples/sec @ 10 bits
- 250,000 samples/sec @ 9 bits
- 277,777 samples/sec @ 8 bits
- 294,118 samples/sec @ 7 bits
- 333,333 samples/sec @ 6 bits
Needless to say, I am VERY pleased with the ADS7822P’s I purchased!
Click on the link to download the new archive: ADS7822P 200Ksps-333Ksps Driver
Let me know what you think…