Lattice MachX02 using crystal oscillator

Hello to all,

I'm developing on a Lattice "MachX02 control development kit"(MachXO2 Control Development Kit - Lattice Semiconductor) . On the board there is a crystal connected to PCLKT5_0. I want to use it instead of the build-in oscillator but I can't find any reference on how to use it. On Spartan I just have to use the pin in my source but doing so with the MachX02 don't give me a clock signal. When I inspect the x-tall with a scope I even don't see a signal.

Is there something I have to do to make in oscillating? Can someone give a hint where to look? The documentation on sysCLOCK and PLL design mentions only PCLKT0 to 3 to bee connected to the Center Switch Box.

Greets an hoping on a tip

Jean Paul

Top Replies

on7ami over 11 years ago in reply to michaelkellett +1

Michael, As promised, the results. The TN8080 document did the work. coupling the X-Tal in pin to the in of an inverter and the X-tal out port to the output of the inverter, disabling all pull-up or pull…

michaelkellett over 11 years ago

Looking at the Lattice document "MachXO2-1200HC Control Development Kit" I can't locate PCLKT5 on the schematic (either by looking or by search function in PDF). Where on the schematic are the connections and what is the reference to the crystal.
Crystal X2 on page 7 is connected to PL3A and B on page 14 which is CLKT3_2 and CLKC3_2.

MK
Cancel
Vote Up 0 Vote Down

Sign in to reply

Cancel
on7ami over 11 years ago in reply to michaelkellett

Michael,

Well, I have the MachX02-4000 on my dev-board, but looking at the documentation of the old dev board with the MachX02-1200, I found a remark on the schematics (that disappeared on the newer documentation) where the constructor is referring to a document AN8080 "Using a Discrete Crystal as a PLD Clock Source" that cleared the whole thing out. Seems you have to make your own oscillator with a not port between the x-tal pins. I'l give it a try and come to tell you if it works.

Greets
Jean Paul
Cancel
Vote Up 0 Vote Down

Sign in to reply

Cancel
michaelkellett over 11 years ago in reply to on7ami

Good luck - I downloaded the first board manual I found on the web site - luckily I didn't think to check if there were others.

MK
Cancel
Vote Up 0 Vote Down

Sign in to reply

Cancel
on7ami over 11 years ago in reply to michaelkellett

Michael,

As promised, the results. The TN8080 document did the work. coupling the X-Tal in pin to the in of an inverter and the X-tal out port to the output of the inverter, disabling all pull-up or pull-down on both pins then using the input pin as the oscillator and he did it.

grts,
JP
Cancel
Vote Up +1 Vote Down

Sign in to reply

Cancel
michaelkellett over 11 years ago in reply to on7ami

Great - thanks for the feedback. I normally use complete oscillators having has so much trouble with processor external crystal oscillators but there are some applications where the extra cost is too much.

MK
Cancel
Vote Up 0 Vote Down

Sign in to reply

Cancel