r32190
Junior Member
Posts: 57
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Post by r32190 on Aug 3, 2007 12:30:15 GMT 7
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Post by adriantam on Aug 10, 2007 21:05:16 GMT 7
Can you tell more details?
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r32190
Junior Member
Posts: 57
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Post by r32190 on Aug 11, 2007 7:46:14 GMT 7
I tell the concept 1st.
Freescale 834x CPU can operate the CPU core from 266 to 667MHz. There are multiple PLL (simply speaking clock multiplier) inside it. In order to avoid the modification affecting the serial port and DDR clock rate, only the CPU PLL would be modified.
The internal bus clock (CSB clock) remains 266MHz, then you can modify it the CPU multiplication factor from x1 to x1.5.
The CPU fetchs a HRCW (config stuff) from the 1st 32 bytes of the flash during reset. The factor is at the HRCW.
The modification can be done at u-boot. Modify the CPU multiplication factor only. Copy the 1st sector ( I guess 256B) to the DDR, modify it and write it back to the flash.
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Post by adriantam on Aug 13, 2007 21:00:48 GMT 7
Thanks a lot. Do you have any good documentation of the processor to suggest? In Freescale's web, seems only the MPC8347E can be found but what the kernel reports is MPC8347. Are they the same?
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r32190
Junior Member
Posts: 57
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Post by r32190 on Aug 14, 2007 8:08:32 GMT 7
Freescale PowerQuiCC family suffice "E" means encryption engine. Frankly, with or w/o "E" contains the engine. Owing to this engine still has strict export control to places such as N Korea and China. The documentation on the web is good enough. What the key factor is the u-boot operation. If the operation is not correct, you may need to reflash the board with the JTAG port. It will be more complicated, and I don't know where is the JTAG port yet  |
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Post by appleman1234 on Mar 21, 2008 9:37:18 GMT 7
Having recently acquired a N1200, I was wondering which uboot command you used to overclock the CPU ? I have read the datasheets and have narrowed it down to 6 possible uboot commmands that could be used but I am not sure which is the correct one ?
Also from examining the the mpc8349mds_flash.c file, * 0 : 0xFE00 0000 - 0xFE01 FFFF : HRCW (128KB) is supposed to the HRCW, and the Data sheet has 3 possible valid options. I am assuming this HRCW is on the u-boot partition which is from 0 to 0x040000 (256KB). Is this correct ?
What methods can be used to flash the device ? I believe DD in the Thecus Linux environment is one way (probably the least safe way) and the one method via the Uboot bootloader itself. (more self but requires serial cable, which I am in the process of getting, but don't have yet.)
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r32190
Junior Member
Posts: 57
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Post by r32190 on Mar 28, 2008 12:29:51 GMT 7
It has been a while. You are correct, 0xFE00_0000 to 0xFE01FFFF is the HRCW. Actually, the value would be stored to the CPU is 32 bit wide, but in order to simply the decoding, 128KB is reserved.
The best way to program HRCW is to reserve a 128KB area at the DDR, make sure nobody else is using it and copy back to the flash.
Type "help" at u-boot prompt will show available instructions.
I highly recommend you improve the ventilation and the heatsink 1st. I posted two threads about it.
Now my overclocked N1200 is very stable, continuous 58 days operating now.
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Post by marty on Apr 24, 2008 23:57:01 GMT 7
Do you think the 8347 400Mhz in N3200 can also be overclocked?
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r32190
Junior Member
Posts: 57
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Post by r32190 on May 15, 2008 16:21:47 GMT 7
8347 is in plastic package. Its dervative 8349 is in metal package, can run up to 667MHz.
Theortically, you can overclock it to 533 or 667MHz, but very good cooling methodology is required.
Factory default (non-conductive adhesive) will definitely harm the CPU.
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