exxos's Atari, Amiga & retro forum

I'm looking at how to do clock generation for the next revision of the TF360....

I'd like to be able to get a bunch of frequencies out selectable by something simple. I spotted this one but i'm not dead set on it..

https://uk.rs-online.com/web/p/pll-freq ... s/1703521/

I'm open to opinions on this but i'm not going to use a chip that needs programmed via SPI/I2C etc. Thats too complex to do in the CPLDs.

EDIT: This one is also good

https://uk.rs-online.com/web/p/pll-freq ... s/1628970/

With 25Mhz crystal input we could have the TF360 boot at 50Mhz by default but then have a command line app that could ramp you up to a bunch of options such as..

62Mhz
75Mhz
78Mhz
80Mhz
100Mhz

This would be excellent. Especially when most of the time the higher clock speeds are not needed (ie a WHDLoad gaming session with 2D based games). This also would certainly help with heat on the A1200 application. This would also solve the "I bought the 78Mhz version but my 060 wont do that, can I send back my TF360 for 50Mhz version".
Superduper etc can then guarantee a card that will work at 50Mhz but depending on setup 100Mhz is possible.

The Warp1260 guys said they were also having adjustable clock speed, dont know how they are doing it though. A picture of their populated PCB might yield the answer.

i do remember that ive thinkered with IDT ICS 570AILF, it's 5V chip so may be perfect for retro hardware
https://www.idt.com/document/dst/570-datasheet
Digi-Key part numper: 800-2373-5-ND
this multiplier can also have several profiles switched by resistor/jumper settings,
don't know will it fit Your needs or not..

"I bought the 78Mhz version but my 060 wont do that, can I send back my TF360 for 50Mhz version".

I will never sell an option like that. Its my idea of hell.

The Warp1260 guys said they were also having adjustable clock speed, dont know how they are doing it though. A picture of their populated PCB might yield the answer.

They're using an FPGA which probably has a clock generator tile in the fabric.

8 Bit Dreams wrote: 08 Sep 2019 13:42 i do remember that ive thinkered with IDT ICS 570AILF, it's 5V chip so may be perfect for retro hardware
https://www.idt.com/document/dst/570-datasheet
Digi-Key part numper: 800-2373-5-ND
this multiplier can also have several profiles switched by resistor/jumper settings,
don't know will it fit Your needs or not..

Yeah i didnt get on well with that chip for some reason. I cant remember why.

I dont actually need the zero delay part because the reference clock is fed into the CPLD and it does complex clock generation from there.

EDIT: I remember why i didnt like that chip.. when connected to a tri-stated pin the M value in that truth table didnt work.

There is also "B" version of this chip with the only difference that it runs with 3.3V instread of 5V..

need to admit this would be very nice feature - to make clock switchable, will save a lot of hassle and headache

So I’ve thought about this a little...

The TF360 will default to 50Mhz... I will provide a tool to let you change it and a library module that will read the settings from nvram and update during boot.

This is likely to mean you’ll need a new ROM to take advantage of this unless I can squeeze a module into the cpld

Basically your TF360 settings will look like a game slot.

Looks like a feature creep...

I’m balancing this against the sodomization that will occur to boards if end users have to do smd soldering to change speed.

terriblefire wrote: 09 Sep 2019 10:23 I’m balancing this against the sodomization that will occur to boards if end users have to do smd soldering to change speed.

How about adding a few jumpers instead?

Yeah...
or blobs of solder