SPI mode.

Projects General Guidance
1

I am getting a stream of data at pin 11 (MISO) but only 100mv p-p. This is with no load. The logic starts at 5V, then drops to near zero, then the small level data stream. Data from pin 11 works fine with 74HC595 sketch!

Also, the SS pin does go low when requested but the SS line from the FPGA is pulled up to 3.3V through a 100K resistor and will not get pulled down lower than 3.3V via pin 11.

Any ideas?

  • howdyrichard
2

Since the MISO line is the problem I would look at the slave device rather than the Arduino, since the slave will be driving the MISO line.
Pin 11 shouldn't be connected to the SS pin, I'm not sure what you mean by pulling it down via a 100K resistor.

3

Post a wiring diagram and links to the used hardware!