Hi, still have a broken cpuboard with spare 7457 which VCore requirement is too low (1.1)


I have measured the voltage of my unpopulated G4/745X board using pin A22 as ground and VDD (VCore) pins J9 and J11, both gave the same results.

http://www.nxp.com/assets/documents/d ... data-sheets/MPC7457EC.pdf

Pinout for 7457 begins at the end of page 40.



And it seems that each VCore jumper setting in the official Amigaone manual is off by one, they are actually for the VCore value setting that is listed above it.

http://intuitionbase.com/a1_xe.pdf (last two pages)


"ON OFF ON OFF" jumper short, which is meant for 1.59, is actually 1.54!

"OFF OFF ON ON" Jumper short, meant for 1.94, is actually 1.89

"OFF OFF OFF OFF" jumper short, meant for 1.34, is actually 1.29

"OFF OFF OFF OFF" jumper open, meant for 1.244, is thankfully for me, 1.20 volt (rounded as 1.2?)


Is this suppose to be like this ??


I haven't tested every setting, it is a bit time consuming as the solder pads are too close together, but if every setting is off by one then I think that these are the real VCore settings for the shorted jumper, with 1.2 at the bottom for convenience.

https://s7.postimg.org/ye530f72z/Amiga_One_VCore_short.jpg


I will be contacting NXP what my 7457's maximum VCore settings are, with the discovery of the 1.2 volt setting I am thinking about running my 7457 with a higher clock speed to be able to cope with it.



Could anyone point Criscot towards this? he seems to have a lot of experience with the XE and he might be able to explain it.
I think that he has a Facebook or Twitter account, I don't have one myself.

@Hitman
I think K-L means the Soundblaster Live! and the SB 128.

Both work but don't get the 128, it is a older card based on the Ensoniq PCIAudio soundcard which sounds average and in this comparions shows that it is a CPU heavy card under Windows and might also be for AmigaOS.

https://www.youtube.com/watch?v=TC01uiyuJxI
AudioPCI is listed here as the 'Mystery card'

The Live! is much better but I read now and then that the Live! chip is actually not a pci compliant chip and requires software work arounds. I think that it might be unstable.


My recommandation for a good, simple, 16 bit soundcard would be one based on the CS4281. (found in the Sam440ep)

Here's one
http://www.ebay.de/itm/Pine-Crystal-4 ... 69e775:g:D8UAAOSwawpXuMkd

More can be found on eBay if you search for 'Crystal PCI' instead of 'CS4281 soundcard', carefully check the chips though! some have a CS4280 which does not work.



And for 24 bit playback and higher sample rates one based on the Envy24 HT
like this one
http://www.ebay.de/itm/M-Audio-Revolu ... 56e0e5:g:o-wAAOSw6n5Xs4zD


As a headsup, LyleHaze is also working on an audio driver for the Radeon HD, so don't go for a very high end Envy24 HT card if digital audio is your thing.


*edit*
Erm, I completely ignored your question :)
The Envy I listed here is guaranteed to work but the CS4281 card i listed here is such a simple design that it HAS to work, its identical to my ASound Express II, CS4281 paired with its CS4297A codec for which it is designed for.

@Raziel

I doubt they would even remember it at all, wouldn't bother asking if I knew Mai was Chinese.


I'm going to prod the motherboard with a multimeter some weekend..

Does anyone know where I could contact the engineers of this board ?

@Severin

There are more VCC_CORE settings in page 13 and 14

Hello

The 7451 CPU on my module has cracked due to the pressure of my heatsink.

I accidentally bought an energy efficient version of the 7457 which requires 1.1 volt, (MC7457RX1000NB)
the lowest the XE can provide is 1.34 volt.

I'm thinking that changing a resistor on the module or motherboard may do the trick, but which one?


I'm inexperienced with eletronics, can anyone help me out?







If anyone needs a picture of a empty module:

https://s31.postimg.org/ei7psg4ej/Front.jpg
https://s31.postimg.org/sdalono7f/Back.jpg

The silkscreen on the front has discolored a bit with poor lighting (did my best!) making it a bit hard to read,
I think Hans de Ruiter so happens to have (or used to advertise on his site) a program to improve the white point in such images?