There's no issue with the MOSI, MISO, SCK pins. However, I'm a bit concerned about contention on the CSN (P0.3) pin.
Table 98 in the nRF24LU1+ product spec notes that for P0ALT[1:0] = "01", P0.3 is "Configured as output, typically used for Master SPI, see chapter 9 on page 99." That's not at all comforting -- I would hope the pin direction is still controlled by P0DIR!
If setting up master mode via P0ALT[1:0] = "01" sets up P0.3 as an output, then I'd have contention between the nRF24 and the 74HC1GT50 output.
Thus, I'm considering removing the non-inverting buffer and directly connecting the CSN pin on P2 to the nRF24LU1+. I'd like to know:
- Why was a non-inverting buffer used on the CSN pin, but not on other SPI pins?
- Why does the output of this buffer go to both P0.3 and P0.5?
- Any warnings/concerns you'd advise WRT to removing it (in terms of using/re-flashing the CrazyRadio PA)?
- Has anyone looked SPI Master mode and the effect on the P0.3 directionality (if there actually is any)?