TF330 Clock Crystals

68030 + SDRAM + IDE

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terriblefire
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TF330 Clock Crystals

Post by terriblefire » Sat Mar 30, 2019 9:45 am

Since a wider audience has started building the TF330 I've had a few enquiries about TF330 clock frequencies....

The TF330 CPU is LOCKED to 50mhz.

It will not work reliably at any other speed. There are tricks in the CPLD that rely on at least a 100Mhz crystal.

It uses a few clever tricks to keep the CPU cool (that i've gone over in my videos) to make sure that pretty much any 030 rated 33Mhz or higher will work at this speed. That said a small heatsink is maybe a good idea since its an enclosed space.

Why have I done this? Well 2 reasons.

1. Basically since we can get 50Mhz out of cheaply available 030s it doesnt make sense to do any other speed. I had originally intended to have a 25Mhz option but that seems dumb when for £10 you can get a 50Mhz capable CPU.

2. I dont want to support all the different combinations. With the TF530 i have 4 boards built with different clock speeds etc. It ate a year of my time and there are enough other permutations to test (AKiko revisions, CPU versions) without having to check all these clock speeds.

In short. Use a 100Mhz crystal otherwise I expect it will not work. There is no reason to use less than 100Mhz, If you push beyond 100Mhz your mileage will vary. 110Mhz would be the absolute limit.
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