MCF52211 & MCF52223 documentation questions

[MrBean]

We are designing a board with an MCF52223 (possibly an MCF52211)

The MCF52223 Reference Manual is very bad.

I think it is a must to overlay the MCF52211 Reference Manual on it.

Questions remaining:

The MCF52223 Reference Manual states that the reference  crystal is 1-16MHz (par 5.2)

The MCF52223 Reference Manual uses an 8MHz reference  crystal (figure 5.11)

The MCF52211 Reference Manual states that the reference  crystal is 1-48MHz (par 6.2)

The MCF52211 Reference Manual uses a 48MHz reference  crystal (figure 6.12)

The MCF52223EVB schematic (that is not provided by FreeScale but by Axiom altough it is a FreeScale product, not an Axiom product) uses an 48MHz crystal...

Does the MCF52223 need a 48MHz crystal or an 8MHz crystal ?

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The pin function desriptions of the MCF52223 Reference Manual (par 2) show USB pin function in the quad function selections.

The pin desriptions of the MCF52223 Reference Manual (par 2.4 and on) show *no* USB pins.

(Not even USB_DP and VDD_USB).

The MCF52211 Reference Manual shows removal of the USB function pins in the Revision history (Appendix B.1)

What should i connect VDD_USB to ? Just to Vdd ?

Does the MCF52223 actually have the quaternary USB pin functions ?

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PTDPAR (0x1000_0070) is not present (Reserved) in the MCF52223 RM ....

Altough page 2-5 and chapter 21 make me doubt that.

Do the MCF52223 and/or the MCF52211 have a working PTDPAR ? 

Header files i found after a long search seem to disagree.

Not only about PTDPAR but also about bits in it (eg. PWM2/PWM3)

(*sigh* why is it a puzzle, *not* documentation?)

[RichTestardi]

> Does the MCF52223 need a 48MHz crystal or an 8MHz crystal ?

I believe you can use either.

I have run the part with just the internal 8MHz relaxation oscillator, and it seems to work just fine on USB; however, I would not recommend this except in prototype applications since the USB full speed spec requires a 2500ppm clock tolerance, and the relaxation oscillator has a 20,000ppm tolerance.

The disadvantage of using an 8MHz crystal is that USB *has* to run at 48MHz, so you have to PLL from 8MHz to 48MHz and set USB_CTRL:CLK_SRC to 3, limiting the CPU speed to the same speed as USB (48MHz); the advantage of using an 8MHz crystal is that you can run the exact same SW (PLL dividers, etc.) as with the relaxation oscillator, with just a change of the CLKMOD0 pin.

The advantage of using a 48MHz crystal, on the other hand, is you can drive USB directly from the oscillator by setting USB_CTRL:CLK_SRC to 1, and then you can PLL the CPU up to 64MHz or 80MHz, depending on the part (I do this).

> What should i connect VDD_USB to ? Just to Vdd ?

I connect it to VDD, but I just followed the DEMO board schematic.

-- Rich

[MrBean]

The MCF52223DS par 2.7 page 33 states that the crystal reference frequency is min 2MHz and max 10MHz.

48MHz is right out .. (holy handgrenade, anyone ? )

The MCF52211DS states the same btw, max 10MHz ....

PS: I see now that it is not the crystal frequency that is meant here, but the frequency after the predivider.

Message Edited by MrBean on 2008-12-04 08:38 PM

[RichTestardi]

> The MCF52223DS par 2.7 page 33 states that the crystal reference freqency is min 2MHz and max 10MHz.

I think that's the limit for the PLL input when driven (indirectly) by the crystal.

But the PLL gets the input *after* the pre-divider.

So when you run a 48MHz crystal (like all the DEMO boards do), the pre-divider divides by 6 (which is actually its default setting).

This results in 8MHz to the PLL input, which is within spec.

The diagram I always send folks to is figure 5-1 in MCF52223RM.pdf.

-- Rich

[MrBean]

I will assume for now that this (from MCF52223RM) is utterly wrong:

5.2 Features

Features of the clock module include the following:

• 1- to 16-MHz crystal, ......

I'll take a 48MHz crystal as it seems to help the usb controller.

(there is a note added on the bottom of the clock figure MCF52211RM)

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Found Vdd_USB in the 52223DS -> Vdd

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That leaves the USB alternate pin functions and PTDPAR as remaining questions.