On 06/07/11 12:23, Andreas Galauner wrote:
Also the pinout is kind of "weird":
1 #CS
2 #CS
3 SI
4 NC
5 SO
6 VCC
7 SCK
8 GND
Why is CS# connected to two pins? The resistance between those two pins
is 1 Ohm, so they are connected directly. Interestingly the are
connected through a 0 Ohm resistor. Any ideas on that?
I don't know the answer, I'm just having a guess here.
It could be that one of the #CS pins is connected to the flash chip, and
the other is connected to the SPI controller (or whatever you call the
thing an SPI flash chip is connected to on a computer motherboard). If
that were the case then if the 0Ω link wasn't there you would be able to
connect an SPI chip and a switch to that port. The switch would either
short pins 1 and 2, to select the internal flash chip, or would connect
whichever #CS pin is connected to the SPI controller to the #CS pin on
the external SPI flash chip in order to select that chip instead.
Does that sound like a possibility?
--
Andrew.
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