Testing various ATMegas in the Uzebox

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Jubatian
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Re: Testing various ATMegas in the Uzebox

Post by Jubatian » Tue Feb 20, 2018 10:43 am

nicksen782 wrote:
Tue Feb 20, 2018 5:10 am
The following is just my two cents as i continue to watch this thread:

I like the idea of a drop-in replacement for the ATMEGA644. However, isn't it important to have a stable and repeatable product?

The goal is to just replace the ATMEGA644 DIP, right? What if it could be an entire circuit board (mini of course) that is made to have a compatible pin-out? That seems like a better idea. This 1284 idea has been up and down for years and always with the same result: inconsistent or not working well.
I rather posted this for the ATmega644A and ATmega644PA which weren't tried (or told about) in Uzeboxes before, confirming that they might also work well. The 1284 from my part was just a curiosity (and that I am experimenting with the idea of a different console design with two of these, non-overclocked).

nono34
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Re: Testing various ATMegas in the Uzebox

Post by nono34 » Tue Jun 05, 2018 10:22 am

HI
I AM new on this forum and also i don t know how to code game . but i code in basic for avr. and i am interested to create game.

well i use atmega128A THAT WORK AT 40MHZ

i don t know it it can be usefull for the UZEBOX and if it will work properly.

how to do that

simpli use a external oscillator on one of xtal pin depending on the micro .

set the fuse bit of the micro to external oscillator .

you can use a metalic ttl oscillator with 5 volt . in fact it is a quartz with ttl output signal supplyed in 5volt


BE CAREFULL to have for exemple the same oscillator at 20MHZ FOR EXEMPLE BECAUSE IF IT DON T WORK AT 40MHZ YOU CAN SWITCH THE OSCILLATOR TO 20 MHZ FOR REPROGRAM THE AVR OTHERWIZE THE AVR WILL NOT RESPOND TO PROGRAMMER BECAUSE THE CLOCK IS NOT GOOD

DID anyone can tell me if uzebox work at 40mhz and what will be the possible enancement

thank you

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Jubatian
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Re: Testing various ATMegas in the Uzebox

Post by Jubatian » Tue Jun 05, 2018 4:43 pm

nono34 wrote:
Tue Jun 05, 2018 10:22 am
HI
I AM new on this forum and also i don t know how to code game . but i code in basic for avr. and i am interested to create game.
Hi! We don't have a Basic interpreter at the moment, you would have to learn C, which is an useful skill to have. There are some games and tutorials on the Uzebox master repository, it is all open source, so you can experiment with them!
nono34 wrote:
Tue Jun 05, 2018 10:22 am
well i use atmega128A THAT WORK AT 40MHZ

i don t know it it can be usefull for the UZEBOX and if it will work properly.
I guess you are building your own then. If you had indeed seen it running at 40MHz, that's nice, it should work fine within Uzebox. You will have to use a 28.636363 MHz crystal (NTSC colorburst * 8), which is required due to the video: Uzebox needs to produce that exact timing defined in the NTSC standard, and of course, audio likewise demands exactly this frequency. So pick up a 28.636363 MHz oscillator!

You will likely have difficulties with the bootloader with that ATmega128A as it has 128Kbytes Flash, so the bootloader would have to be placed at a different location than on the ATmega644. But you would be able to load .hex files with a programmer, so you may try that! For a fully functional Uzebox, especially if you don't have too much experience with microcontrollers yet, it could be better to just pick up an ATmega644 (an ATmega644A, ATmega644P or ATmega644PA should also work) for now, and experiment with different micros later.

nono34
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Re: Testing various ATMegas in the Uzebox

Post by nono34 » Tue Jun 05, 2018 5:59 pm

ok
thank you jubatian i will try a atmega644 .

thx

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