When booting in QSPI mode, what is theQSPI interface clock frequency while the FSBL (14.3) is executing?
What if I want to increase that frequency because my board is capable of higher frequency on the QSPI interface clock?
XPS lets you choose the QSPI reference clock (maximum frequency is 200 MHz).
The FSBL in the function InitQspi() in the module qspi.c sets the following defaults:
- Change the baud rate to DIV/8 prescaler value
- Set the USE loopback bit ( but the loopback is actually disabled because the prescaler is not DIV/2 )
For Example, if the QSPI reference clock is 200 MHz, the default QSPI interface clock will be 25 MHz.
If you want to speed up the QSPI interface clock, simply change the divider prescaler to DIV/4 or DIV/2 in your FSBL.
Note: If DIV/2 is selected, the loopback automatically enables because the loopback bit is set.