Hi Matt,
On 10/09/27 15:06, mattschinkel wrote:
Thanks Rob, after much guessing values, I got it to work with serial.
I hope it is an educated guess! I would agree with you that the oscillator(s) are pretty complicated (to configure). But when you take the time to read chapter 2 of the datasheet or study the schematics (Figure 2-1) you should be able to select the proper settings (I'm pretty sure I'm not over-estimating your intellectual capabilities). Don't you have a suitable scope or frequency meter to measure the resulting frequency?
I'll try USB soon. The device file is ok, sorry about that I must have misread something. How is the OSC is calculated with these working values? Why is there P1(no devide) on CPUDIV, when on 18F4550 it is P2(div 2)?
The PLL module requires a 4 MHz input and produces 96 MHz output. So when you want to use the PLL module you must reduce the actual oscillator frequency to 4 MHz.
In figure 2-1 you can see that the 18f4550 taps the CPU frequency directly after the PLL module while the 18f6750 taps it after a [1:2] divider. Since both processors can run up to 48MHz for the 18f4550 you have 1:1 (P1), but for the 18f67j50 you'll 1:2 (P2).
Don't ask me why all PICs are different!
Can I use Internal Oscillator for USB? What settings can I use?
Yes, why not, see fig 2-1. pragma fuse_def OSC INTOSC_NOCLKOUT_PLL INTOSC gives 8 MHz, so PLLDIV should be P2 [1:2] Maybe also needed: OSCCON_SCS = 0b00 Rest is the same as for HS_PLL Note: I have not tested this!
include 18f67j50 -- target PICmicro -- include chip pragma target clock 48_000_000 -- oscillator frequency -- configuration memory settings (fuses) pragma target WDT disabled -- no watchdog pragma target PLLDIV P5 -- divide by 5 - 20MHZ_INPUT pragma target CPUDIV P1 -- no cpu system clock divide pragma target OSC HS_PLL -- HS crystal or resonator OSCTUNE_PLLEN = 1 -- set 96mhz pll _usec_delay(1_000) -- wait for OSC PLL to settle
Seems OK to me (with a 20 MHz crystal/resonator!). But you might specify more config bits, esp. IESO and FCMEN. Regards, Rob. -- R. Hamerling, Netherlands --- http://www.robh.nl -- You received this message because you are subscribed to the Google Groups "jallib" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/jallib?hl=en.
