Start from nature and take a trip for venture

Wolfgang Spraul wolfgang at
Tue Jul 21 10:07:53 EDT 2009


> Looking at the BOM I see a jz4720 is used. At what
> speed? The Ingenic data sheet mentions both 240 and 336 MHz, while the
> Ben product page OTOH mentions 360 MHz.

there was a lot of back and forth between 4720 and 4740 for us.
You are right, 4740 datasheet says 360 MHz, 4720 datasheet says 336 MHz.
We looked at a running Linux on one of our boards using a 4720, and it showed

PLL Freq       : 366.00 MHz
CCLK           : 366.00 MHz
HCLK           : 122.00 MHz
MCLK           : 122.00 MHz
PCLK           : 122.00 MHz
LCDCLK         :  73.20 MHz

So I thought (my mistake) this means 360 Mhz :-) Wrong!
The 4720 we will ship the Ben NanoNote with can run at several speeds, but it
seems the highest is 336 Mhz.
While it's the same die as 4740, the selection process for 4740 is harder so
what is sold as 4720 can only be run up to 336 Mhz.

The reason we chose 4720 is because it consumes less PCB space (the device is
really tiny for what it can do, wait until you have one...)
More importantly, the whole engineering concept is around simplicity.
4-layer PCB, the back of the PCB filled with keys across the whole space.
If we would switch to BGA (4740), we would either have to remove keys and/or
add PCB layers, and have less PCB space for things we might want to add in
the small form factor.

Bottom line - we want to keep everything simple as it is, it ships with 4720
max speed probably 336 MHz. If it turns out to be more in the end, welcome
bonus but don't count on it.
I will correct the product spec now. Thanks for the feedback!

> Is there more info on the jz4720 than in Jz4720_ds.pdf? I surely hope so!

One of the things we are working on with Ingenic. We hope they will open up
more complete versions of their datasheets, which exist. Right now we can
only give access to these versions under NDA.
Same situation as with Samsung (gta02-core), but in both cases we are working
on it.


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