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From: Michael A. Terrell on 20 Oct 2009 19:14

Jim Thompson wrote:
>
> Why, oh why, is it that leftists are so ignorant and vocal ?


Why weren't their parents both neutered?


--
The movie 'Deliverance' isn't a documentary!
From: krw on 21 Oct 2009 00:17
On Tue, 20 Oct 2009 14:22:47 -0700, John Larkin
<jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote:

>On Tue, 20 Oct 2009 20:51:24 GMT, Jan Panteltje
><pNaonStpealmtje(a)yahoo.com> wrote:
>
>>On a sunny day (Tue, 20 Oct 2009 13:06:16 -0700) it happened John Larkin
>><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in
>><lk5sd51tusgop3dsd3f9gs6n0inm2vnsqh(a)4ax.com>:
>>
>>>
>>>Our designs are getting increasingly FPGA-centric, and it usually
>>>doesn't make sense to partition a design into multiple chips, so the
>>>ball counts keep going up and the PCB routing gets nastier and
>>>nastier. Are serial busses the answer?
>>>
>>>John
>>
>>Many years ago I suggested in comp.arch.fpga they make a 40 pin DIP FPGA with
>>serial...
>>But then there are applications that need that many I/O pins, like
>>a 512 channel PWM light dimmer for example.
>>The success of i2c has proven serial is cool.
>>Speed gets problematic too, as serial is one thing at the time,
>>so that would mean optical.
>>Now we will get that new Intel 'light peak', maybe it will be an I/O option in FPGA too.
>>And then there is memory interfacing, and PCIe, nothing will likely ever get simpler,
>>until Microchip starts making 40 pin DIL FPGA's :-)
>>
>
>I was thinking of LVDS and RocketIO type busses, similar to
>PCIexpress, several gigabits per second over a differential pair but
>looks parallel inside the FPGA. Things like fast ADCs and DACs and
>even DRAMs could go serial and save a lot of balls. People would need
>to get organized.
>
>I2C is sort of a dog.

No "sort of" about it. SPI is a lot simpler and faster, though it is
no speed demon either. I2S is kinda nice, for anything that takes any
data volume, like multi-channel digital audio. Different purposes,
though.

>We do use SPI for slow DACs, ADCs, temperature sensors, serial eeprom,
>stuff like that when we can. Sometimes we drive a shift register, like
>a 74HC595 maybe, to create some port pins away from the FPGA or uP
>with two or three traces.

Yep, SPI is easy. Whe've had 10x the problems with I2C for about 1/10
the performance.
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