[Lenny400] JZ4730 and other documentation (was Re: Coin cell on motherboard)

Paul Boddie paul at boddie.org.uk
Sun Aug 13 19:05:53 CEST 2017

On Sunday 13. August 2017 18.42.58 H. Nikolaus Schaller wrote:
> I haven't seen it either. But AFAIR there were some references to a JZ4730
> User/Programming Manual. The chip data sheet is still available, e.g.:
> 	http://docplayer.net/12271101-Jz4730-multimedia-application-processor-
> While trying to locate it I have found this:
> 	http://d1.amobbs.com/bbs_upload782111/files_25/ourdev_532550.pdf
> which might also give some background on the hardware.

I have seen a similar "board design guide" document before, although this may 
be a slightly later and slightly different version.

The one kind of document that is stubbornly absent is the programming manual, 
though, which is why I believe that it must have been kept internal for some 
reason, or maybe it never existed as such. Sites similar to those above will 
probably yield the programming manuals for all of the other SoCs in that 
product family, but I doubt that you'll ever find one for the JZ4730.


> I remember that I had some application note (?) for I2C to write a new i2c
> driver long time ago. But I didn't find it or a copy any more. Seems to
> have gone in digital deletion.

Well, I think this is mostly an issue of my own comprehension plus annoyingly 
underdocumented hardware. To be fair, having looked at Microchip documentation 
not that long ago, and despite that being a very established company with a 
long record of writing things down for others to work from, I think there's a 
growing disconnect between the engineering departments and the people given 
the job of describing the product.

Anyway, as I noted, I have been looking at the JZ4730 and trying to make some 
sense of it, and some progress with the JZ4740 (and even JZ4780) means that I 
probably have a slightly better idea about some of the things that I was 
mostly guessing at before. That isn't to say that I can necessarily write 
coherent Linux driver code, though.


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