To me it seems more intuitive to have the line say "0" when not in use, but this is really totally arbitrary. This only sets the line's data value when not in use, so you can pick either. I usually use a pulldown, but you can use a pullup just as well. A weak, even 100 kΩ, pulldown keeps the line at the logic low level when not in use. They can cause oscillations and higher than specified current draw inside the receiving chip. However, intermediate voltages on some digital inputs can cause trouble. Only the slave with slave select asserted is allowed to drive the line, so when no slave is selected, the line floats.įloating MISO doesn't cause any data problems because it only floats when its value is meaningless and the master shouldn't be looking at the line anyway. I sometimes put a pulldown on the MISO line because it could be floating for extended periods of time. As far as I know, SPI lines are always actively driven in both directions.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |