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?