How much is the maximum speed one can get from GPIO pins in Cubieboard2. I have tried several C codes that can access (write) into memory address of the GPIO pins, but I could not get the speed more than 2MHz. Is there anybody who could get a more speed over GPIOs?
I need the speed of 12 Mhz and so I will be very thankful if someone can share experiences..
On an A20-OLinuXino-MICRO-4GB board https://www.olimex.com/Products/OLinuXino/A20/A20-OLinuXino-MICRO-4GB/ I got to just under 8 MHz bit-banging a port through mmap. Same chip, I think the same speeds. Solid 8MHz running standalone code.
After configuring all pins of PI to be outputs:
volatile uint32_t tstVal = 0;
tstVal ^- 0xffffffff;
*PI_Data = tstVal;