I am using Arduino(does not matter) and 8 x 12 bit-ADCs to read some values. I created a prototype which consists of a Shift Register(SR) and all outputs of SR are connected to individual ADC's chip-select pin. During boot, I set all output of SR as HIGH.
I select the ADC by pulling the specific output of the SR as LOW and then talk to the ADC. As soon as my communication is finished, I again set all output of SR as HIGH. This is all working.
During some testing, I found that if all SPI (ADCs) are pulled HIGH (none should be talking) and if I read MISO, I was getting some random data. I realized that MISO was floating and added a 100K pull-down (weak pulldown!) which sorted this out. After this, if I listened the MISO while all ADCs were HIGH, all I get is 0s (Yey!).
My question is that does it make sense to pull down MOSI and CLOCK as well? Will it create any problem?