Hi, I adapted the code from Derek Molloy example - http://exploringbeaglebone.com/chapter13/ - https://github.com/derekmolloy/exploringBB/tree/master/chp13/adc - to read this adc - ad4000 - http://www.analog.com/media/en/technical-documentation/data-sheets/AD4000.pdf with a 500kHz sampling. The only thing i changed, according to communicate with this adc, is that i read 16 bits on the PRUADC.p and TIME_CLOCK is 1 (12.5Mhz for SPIclock). I'm not an assembly expert, so i really can't figure out the problem.
I tried read the this adc from the SPI0 of BBB(using Derek Molloy exampels too http://exploringbeaglebone.com/chapter18/) , of course not with a 500kHz sampling, just for test, but the problem is the same, i'm working on this for more than 4 weeks, and i can't solve the problem, and is not a hardware problem. In this examples, i have in the analog input of the adc, a square wave(3.3 V), and 3 constantes voltages(680mV,1.8V,3.3V), all examples done on PRU, and this are the results: - Y axis -> Volts - X axis -> Number of sample - Vref of the adc is 4V. <https://lh3.googleusercontent.com/-XwrjqFvVtGg/WJsEk4j8sKI/AAAAAAAAABs/syvlHagqHk0CB5y-At3JbOmMsNLpl5n3gCLcB/s1600/pwm.jpg> <https://lh3.googleusercontent.com/-80w756WyytI/WJsEsYqOe9I/AAAAAAAAABw/h0BMszD018gyhgLIMas88OlLQnqCDESvwCLcB/s1600/0.68.jpg> <https://lh3.googleusercontent.com/-r4FQ7bbvFB0/WJsEvqIAe8I/AAAAAAAAAB0/0CGjj9MW2iMwUHA3KXuos2TumCYwEONtgCLcB/s1600/1.8.jpg> <https://lh3.googleusercontent.com/-_5RdOLgXL6E/WJsEyV_cEnI/AAAAAAAAAB4/RzwEyv3SBPM6hUX1LT6yNFbJJ0bk-gB2ACLcB/s1600/3.3.jpg> Any help would be aprecciated. Best Regards, David -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/a69a32ff-0e75-43d7-ba62-88dca26814e3%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
