jz4725

Carlos Camargo cicamargoba at gmail.com
Sat Aug 22 08:59:57 EDT 2009


I think that is necessary make a benchmark for this options, 16 Bits vs 32
Bits Data Bus. We are testing sungale Photo-frame with a custom file sytem
based on openmebedded an we note the following issues:

1. They use an USB wifi dingle: The PCB doesn't have an copper pour area
that help to temperature dissipation, so when the dongle increase his
temperature we experiment problems with the connection. Is necessary take
note about this for our design. I agree with Wolfgang the best way is use an
USB module insteed a USB dongle.

2. We experiment a low speed in navigation, like a tablet Nokia N800. Maybe
because of 64Mb memory, we will buy a 32 MB SDRAM and change the sungale
memory and thes the performance with 128MB.


On Sat, Aug 22, 2009 at 7:15 AM, Wolfgang Spraul
<wolfgang at qi-hardware.com>wrote:

> The Ben NanoNote is using Jz4720 not Jz4725.
> What is the best way to have 64 MB SDRAM with the Jz4720?
> The 4720 has a 16-bit data bus whereas the 4740 has 32 bit, I think
> it's because 4720 has COB instead of BGA, but like you said some
> competitive reasons might be behind this too. Positioning the 4720
> as low-cost and against some other chips.
> I don't know anything about 4725 or 4725b right now.
> Wolfgang
>
> On Sat, Aug 22, 2009 at 02:06:19PM +0200, W.G. van de Hulst wrote:
> > I thought the point of the jz4725 was to be a jz4740-SX (16-bit
> > instead of 32-bit databus) to eliminate one RAM chip and to use LQFP
> > instead of BGA, both measures meant to lower cost and to compete with
> > comparable Rockchip 2706 designs.
> >
> > It seems strange to add it back, but of course there's now the new
> > jz4725b that allows booting from SD, so you can sacrifice the flash
> > chip to avoid requiring more space.
> >
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-- 
Carlos Iván Camargo Bareño
Profesor Asistente
Departamento de Ingeniería Eléctrica y Electrónica
Universidad Nacional de Colombia
cicamargoba at unal.edu.co
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