Observation: Firefox does not allow me to submit the post all the time, but with IE there is no problem.
For my curiosity I have tested also non-PLL with 20MHz external crystal with a simple 1s on/off blinking LED and a counter 0-59s displayed on 2x16 LCDThe settings are:
A = 20MHz
B = div by 5
C = USB-HS = HS = FOSC3:FOSC0 = C2
D = no divide = CPUDIV1:CPUDIV0 = OSC1/OSC2 Src: /1
E = 20MHz = Clock speed (20000000 Hz)
F = USB Clock Selection as 96MHz PLL/2
In the above configuration the CPU receive 20MHz clock directly, non-PLL, and USB clock is PLL and receive 48MHz when FSEN=1 or 6MHz when FSEN=0.
It works fine, but I do not know now about the USB clock synchronization with other devices if I choose such frequency also for USB clock.
If we decide for non-PLL also for USB clock then I suppose we have to choose the external crystal 48MHz in order to get full USB speed.
I really do not know how USB will behave, maybe later I will make some tests, when I choose non-PLL for USB clock, then 20MHz crystal and FSEN=1. I expect will be directly 20MHz for USB clock. Does that frequency allow USB sync and data transfer between PIC18F4550 and other UDB devices as a PC? Or must be always 48MHz? Or generally speaking may be anything between 6MHz and 48MHz?
It is not so important to change 48MHz to 20MHz as long as 48Mhz or 6Mhz from PLL assures the USB communication compatibility, but I ask only for my understating.
The idea is to make next settings, for test and understanding purpose only:
A = 20MHz
B = not important, because PLL will not be sued at all.
C = USB-HS = HS = FOSC3:FOSC0 = C2
D = no divide = CPUDIV1:CPUDIV0 = OSC1/OSC2 Src: /1
E = 20MHz = Clock speed (20000000 Hz)
F = USB Clock Selection as OSC1/OSC2
So, it is 20MHz external crystal, the CPU clock will get directly, non-PLL, the 20MHz, the USB clock will also jump the PLL and get 20MHz, suppose setting FSEN=1.
Would such kind of setting work for USB clock?
For my curiosity I have tested also non-PLL with 20MHz external crystal with a simple 1s on/off blinking LED and a counter 0-59s displayed on 2x16 LCDThe settings are:
A = 20MHz
B = div by 5
C = USB-HS = HS = FOSC3:FOSC0 = C2
D = no divide = CPUDIV1:CPUDIV0 = OSC1/OSC2 Src: /1
E = 20MHz = Clock speed (20000000 Hz)
F = USB Clock Selection as 96MHz PLL/2
In the above configuration the CPU receive 20MHz clock directly, non-PLL, and USB clock is PLL and receive 48MHz when FSEN=1 or 6MHz when FSEN=0.
It works fine, but I do not know now about the USB clock synchronization with other devices if I choose such frequency also for USB clock.
If we decide for non-PLL also for USB clock then I suppose we have to choose the external crystal 48MHz in order to get full USB speed.
I really do not know how USB will behave, maybe later I will make some tests, when I choose non-PLL for USB clock, then 20MHz crystal and FSEN=1. I expect will be directly 20MHz for USB clock. Does that frequency allow USB sync and data transfer between PIC18F4550 and other UDB devices as a PC? Or must be always 48MHz? Or generally speaking may be anything between 6MHz and 48MHz?
It is not so important to change 48MHz to 20MHz as long as 48Mhz or 6Mhz from PLL assures the USB communication compatibility, but I ask only for my understating.
The idea is to make next settings, for test and understanding purpose only:
A = 20MHz
B = not important, because PLL will not be sued at all.
C = USB-HS = HS = FOSC3:FOSC0 = C2
D = no divide = CPUDIV1:CPUDIV0 = OSC1/OSC2 Src: /1
E = 20MHz = Clock speed (20000000 Hz)
F = USB Clock Selection as OSC1/OSC2
So, it is 20MHz external crystal, the CPU clock will get directly, non-PLL, the 20MHz, the USB clock will also jump the PLL and get 20MHz, suppose setting FSEN=1.
Would such kind of setting work for USB clock?