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 Post subject: Re: Pic firm. with SDHC, FAT16/32, Dir, HDD support for YQ091224
PostPosted: Thu Feb 25, 2010 1:29 pm 
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Location: Sydney, Australia
Namek wrote:
Just to know... What are the specs of the actual PIC? :roll:


PIC18LF252 - 32KB Flash, 1536 bytes RAM, No internal oscillator so maximum speed 10MHz.

(If the PIC was driven at 5V, then 40MHz speed would've been possible with internal 4x PLL, but it isn't, so speed cannot be set above 10MHz).

Regards,

Ross..


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 Post subject: Re: Pic firm. with SDHC, FAT16/32, Dir, HDD support for YQ091224
PostPosted: Fri Feb 26, 2010 7:38 pm 
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rossv wrote:
PIC18LF252 - 32KB Flash, 1536 bytes RAM, No internal oscillator so maximum speed 10MHz.

Please correct me if Im wrong.
On Minimig pcb the X2 is a 20.0MHz oscillator and standard 18LF252 PIC is powered at 3.3v.
Or will this PIC internally devide the source clock by two?

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 Post subject: Re: Pic firm. with SDHC, FAT16/32, Dir, HDD support for YQ091224
PostPosted: Fri Feb 26, 2010 9:48 pm 
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Location: Malta
boing4000 wrote:
On Minimig pcb the X2 is a 20.0MHz oscillator and standard 18LF252 PIC is powered at 3.3v.
Or will this PIC internally devide the source clock by two?

All PICs have a machine clock every four oscillator clocks. Thus, the 20.00MHz PIC on the originial Minimig runs internally at a 5MHz clock (approximately 5 MIPS). This 5MHz also acts as the peripheral clock.

All modern PIC18 micros are rated for 40MHz oscillator clock at 5V supply. This means they should give 10 MIPS of processing speed and can do SPI at a 10MHz rate. The only problem is that when operating at lower voltages, the maximum operational frequency is reduced. This would equate to approximately 32MHz (8 MIPS, 8MHz SPI clock).

Cheers!
Edwin

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VGA -> SCART cables currently out of stock - PM me for info


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 Post subject: Re: Pic firm. with SDHC, FAT16/32, Dir, HDD support for YQ091224
PostPosted: Fri Feb 26, 2010 10:24 pm 
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Thanks Edwin, I did not know that before :) this makes the original PIC really slow, no doubt!

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 Post subject: Re: Pic firm. with SDHC, FAT16/32, Dir, HDD support for YQ091224
PostPosted: Mon Mar 01, 2010 12:36 pm 
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Location: Sydney, Australia
boing4000 wrote:
Please correct me if Im wrong.
On Minimig pcb the X2 is a 20.0MHz oscillator and standard 18LF252 PIC is powered at 3.3v.
Or will this PIC internally devide the source clock by two?


Sorry I got confused about X2 and thought it was 10MHz, however it is as Edwin states, and we cannot drive the PIC at full 40MHz speed due to low voltage. A shame because the Minimig actually has 5V supply!

Regards,

Ross..


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 Post subject: Re: Pic firm. with SDHC, FAT16/32, Dir, HDD support for YQ091224
PostPosted: Mon Mar 01, 2010 12:39 pm 
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wolfchild wrote:
All modern PIC18 micros are rated for 40MHz oscillator clock at 5V supply.


The most modern 'K' series of PIC18 with 3.3V operating voltage can run at up to 64MHz.

Regards,

Ross..


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 Post subject: Re: Pic firm. with SDHC, FAT16/32, Dir, HDD support for YQ091224
PostPosted: Tue Mar 02, 2010 7:15 am 
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rossv wrote:
The most modern 'K' series of PIC18 with 3.3V operating voltage can run at up to 64MHz.


Indeed! I didn't know that before. Thanks for the info :) After seeing the datasheet, it seems that one could either remove the 20.00MHz crystal and put a 16.00MHz one, or simply use the internal RC oscillator which runs at about 16MHz. The 4xPLL would then multiply the clock to 64MHz. If the internal oscillator option is usable, this would mean over 3x the actual processing capability without PCB modifications.

Cheers!
Edwin

_________________

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self-built minimig 1.1 :: 10ns SRAM :: 3.5MB RAM :: ARM board

VGA -> SCART cables currently out of stock - PM me for info


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 Post subject: Re: Pic firm. with SDHC, FAT16/32, Dir, HDD support for YQ091224
PostPosted: Wed Mar 03, 2010 10:47 am 
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wolfchild wrote:
Indeed! I didn't know that before. Thanks for the info :) After seeing the datasheet, it seems that one could either remove the 20.00MHz crystal and put a 16.00MHz one, or simply use the internal RC oscillator which runs at about 16MHz. The 4xPLL would then multiply the clock to 64MHz. If the internal oscillator option is usable, this would mean over 3x the actual processing capability without PCB modifications.


No worries. For the full low-down on the suitable PICs for Minimig, see the previous posts in this thread on Page 4.

Regards,

Ross..


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 Post subject: Re: Pic firm. with SDHC, FAT16/32, Dir, HDD support for YQ091224
PostPosted: Sun Apr 11, 2010 7:04 am 
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Joined: Sat Apr 10, 2010 2:34 pm
Posts: 1
Hi,

Just got my 4mb minimig v1.1 and found this post so I updated the pic firmware so I could play around with a hdf and whdload...

I've turned A600 IDE on and selected a hdf file I created in winuae but I just keep getting the purple insert disk screen from ks 3.0...

Is there something I've missed?

Cheers in advance for any help!

Marc


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 Post subject: Re: Pic firm. with SDHC, FAT16/32, Dir, HDD support for YQ091224
PostPosted: Sun Apr 11, 2010 7:25 pm 
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Posts: 1568
Location: .de
Marcb wrote:
I've turned A600 IDE on and selected a hdf file I created in winuae but I just keep getting the purple insert disk screen from ks 3.0...

Dont forget to "enable" just selected .hdf file out of the list as Master device and to soft reset (3-keys) Minimig to enable IDE controler.
Btw: Slave device alone will not work in Minimig.

For permanent hdf support this settings need to be saved within PIC EEPROM like this:
OSD > Settings > exit > scroll down once more to reach > save


In general:
This selected and pre-formated hdf file made in WinUAE may depend on used IDE controller type.
Minimig simulate an A600/A1200 Gayle chip interface driven by ROM internal "scsi.device".
This device will be supported only by kickstart 2.05 (37.350) and kickstart 3.1 (40.063).

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