the internal clock oscilator/circuitry depends on the supply voltage.
For 5V (>4.5V) application it works up to 48MHz, while for 3V3 (<4.5V) the clock circuitry runs up to 20Mhz.
Anyhow, we suggest to use a 'low-frequency' crystal, e.g. 4MHz and using the internal PLL. That gives better EMI result for your system.
I want to know what should using P61/UHCONX pin control UDP (D+) high/low?
And what is the UDP (D+) high and low status?
Hi, please see the 32 Bit Microcontroller FM4 Family Peripheral Manual Communication Macro Part.pdf, CHAPTER 3-1: USB Device (USB Function)
Here a schematic extract form our starter kit
Does this answer your question?
I understand the USB D+ pull-high which is Full Speed. Does this MCU on USB programming mode when USB D+ no level(UHCONX pull-up)?