Hello,
I would like to use the GPIO Clock method for XTAL trim calibration.
The production test document says: “To configure GPIO0 to output the clock signal, write 0x3 to GPIO_MODE register Reg_0x05:00”. And i should observe a 31.25 MHz signal.
By using the following code (modifying the gpio example) on DWM300EVB:
if (dwt_initialise(DWT_DW_IDLE) == DWT_ERROR)
{
test_run_info((unsigned char *)"INIT FAILED ");
while (1) { };
}
dwt_enablegpioclocks();
dwt_setgpiomode(GPIO0_BIT_MASK, 0x3);
I measure a very unstable clock on GPIO0 which vary from device to device.
For example on 1 device i measure 29.38MHz, on another 28.6MHz etc…
All the results are way off the 31.25MHz.
Is there any known issue with this calibration method or do I do something wrong?
Thank you