I am working with a 28035 piccolo, using CCS4 on a Control Card. The SYSCLOCK is set to 60 MHz and is based on the internal clock (verified through the SYSCLOCKOUT output).
I have assigned GPIO17 as a discrete output, and configured it accordingly.
I want to test the response time of this IO, and run the following routine:
GpioDataRegs.GPATOGGLE.bit.GPIO17 = 1;
GpioDataRegs.GPATOGGLE.bit.GPIO17 = 1;
GpioDataRegs.GPATOGGLE.bit.GPIO17 = 1;
GpioDataRegs.GPATOGGLE.bit.GPIO17 = 1;
GpioDataRegs.GPATOGGLE.bit.GPIO17 = 1;
GpioDataRegs.GPATOGGLE.bit.GPIO17 = 1;
GpioDataRegs.GPATOGGLE.bit.GPIO17 = 1;
GpioDataRegs.GPATOGGLE.bit.GPIO17 = 1;
I get the output on an oscilloscope. I expected a square wave consisting of several pulses of approximate width 16.6 nSec.
Instead, the pulse train I see consists of 100 nSec. wide pulses (corresponding to about 10 MHz instead of 60 MHz).
How can I achieve the maximal output response from the digital outputs?
