[Arm-netbook] level shifting on 24-pin RGB/TTL

Luke Kenneth Casson Leighton luke.leighton at gmail.com
Thu Sep 22 02:47:59 BST 2011


On Thu, Sep 22, 2011 at 2:39 AM, Baybal Ni <nikulinpi at gmail.com> wrote:
> Can we use 2 16 bit ones?

 yes, by all means.  or 4 8-bit ones, etc. etc.  the challenge is to
a) find out if this is necessary! b) source reaaally low-cost ICs or
components to do it.

 what i will do is allocate one of the pins to be the "supply voltage"
to the level shifters / buffers, such that the output from all those
pins matches the voltage that the *motherboard* says that it accepts.

 but i really don't want to have to put that in, if it turns out for
example that it's unnecessary!  also, the GPIO pins, again, those
might (yuck) have to be put behind tri-state *bi-directional* level
shifters.  euuw! :)

 l.

> On 21 September 2011 14:36, Luke Kenneth Casson Leighton
> <luke.leighton at gmail.com> wrote:
>> folks, hi,
>>
>> there's something slightly complex that's come up about this
>> EOMA/PCMCIA standard: the possibility that SoCs might have different
>> TTL levels for the 24-pin RGB/TTL output.  does anyone know if that's
>> the case?  should i be putting that Tri-State buffers which also have
>> Level Shifting are required?  if so, what's the best buffer / part -
>> low cost! - that does the job?
>>
>> so far i've found this:
>> http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=AVC16T245DGGR-D-ND
>>
>> it's a 16-bit bus driver IC, only $0.70 in medium-volume quantities.
>> the 32-bit ones are insane prices ($2)
>>
>> there has to be something out there that's lower cost than this!
>>
>> l.
>>
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