Messages in this thread | | | Subject | Re: bit errors on spitz | From | Stanislav Brabec <> | Date | Fri, 12 Mar 2010 10:07:04 +0100 |
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Andy Green wrote: > On 03/11/10 15:42, Somebody in the thread at some point said: > > Andy Green wrote: > > > >> I saw very similar failures for a long time on our iMX31 based device. > >> Eventually I found a Freescale errata where the RAM inside the USB2 > >> macrocell started to make single bit errors below 1.38V Vcore; ours was > >> 1.4V at that time but dipped on CPU load. > > > > Good tip. It seems that nobody ported driver for the voltage control > > chip ISL6271 from 2.4 kernel, and bootloader probably does not set > > correct values.
> Unless there's more to it in the way the zaurus using it that regulator > isn't programmable digitally.
OOPS, I made a mistake and linked ISL6721 instead of ISL6271 there. Now it is fixed: http://www.penguin.cz/~utx/zaurus/datasheets/power/XScale/ISL6271A.pdf
This one has I2C. It is connected to GPIO 3 (PWR_SCL) and GPIO 4 (PWR_SDA).
It is visible between the black plastic and the large circular coil: http://www.penguin.cz/~utx/zaurus/teardown#pcbt
> Reading about your CF Card WLAN related issues they suck down a good > amount of power when their radio is up, I would definitely suggest > monitoring with a 'scope the various rails (Vcore, RAM and whatever it > is the CF Card is powered by) while putting it under load.
I guess that Zaurus has a good power design and that voltage should be constant enough. CF has a dedicated step down (plus 2.8V power detector (Why so low, if CF standard requres more?)), HDD has a dedicated step up/down. USB has dedicated step up. Companion chips use dedicated 3.3V step down. Audio uses dedicated linear regulator. CPU has several dedicated step downs, CPU 3.3V uses step-up to 5V and then down to 3.3V (which is shared only with IOPORT).
Nearest common point between CF card power and CPU power is the battery.
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Stanislav Brabec http://www.penguin.cz/~utx/zaurus
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