ColdFire/68K Microcontrollers and ProcessorsのトピックRe: MCF548x CLKIN to PLL?

MCF548x CLKIN to PLL?

zwilcox — Fri, 19 Oct 2018 22:01:03 GMT

I'm trying to hook up a crystal to the MCF5484.

There's a CLKIN line where it looks like the crystal hooks up to. Usually there's like a CLKOUT or osc_out, xtal_out or something but I'm not seeing that.

This is what I have so far:

Am I missing something?

Thanks in advance
Zach

Edit: Here's the full module for the Test, Reset, and Clock portion

Re: MCF548x CLKIN to PLL?

miduo — Wed, 24 Oct 2018 08:09:13 GMT

Hello,

Please see our evaluation board for the clock scheme:

Re: MCF548x CLKIN to PLL?

TomE — Thu, 01 Nov 2018 05:32:21 GMT

The Data Sheet has a section on the PLL detailing the CLKIN signal in "Table 7. Clock Timing Specifications". The levels and rise time can only be obeyed with an external hybrid oscillator, not a crystal.

In the Reference Manual:

10.1.2 Clocking Overview
The MCF548x requires a clock generated externally to be input to the CLKIN signal.

Tom

Re: MCF548x CLKIN to PLL?

zwilcox — Thu, 01 Nov 2018 23:23:46 GMT

Ahh ok. Cool thanks. I'll need to fix this. That helps.

Re: MCF548x CLKIN to PLL?

zwilcox — Thu, 01 Nov 2018 23:35:33 GMT

Hey miduo‌!

Would you be able to provide the schematic for the eval board?
I don't see it listed here MCF5485 Evaluation Board|NXP

Thanks :smileyhappy:

Re: MCF548x CLKIN to PLL?

TomE — Fri, 02 Nov 2018 02:57:59 GMT

I've just received email on this thread from you (Zachary) asking for the schematics for the ref board. As of this time the post isn't visible here, so I guess it'll get there before this one does.

Anyway...

On the NXP MCF5485 Page under the "Software and Tools" tab there are two "Reference Board" packages. These contain schematics.

Tom

Re: MCF548x CLKIN to PLL?

miduo — Sun, 04 Nov 2018 15:06:32 GMT

Hello,

Actually the M5485EVB is not designed by NXP(Freescale). It was developed by LogicPD. However we had an internal evaluation board which was for internal test. The above schematic is from this board.