Content originally posted in LPCWare by Polux rsv on Tue Nov 29 02:26:24 MST 2011
At least insert a pull-up on the CS line. This is to avoid peripheral beeing selected during reset phase, where ios are not configured yet.
A good practice is to add resistors on every line you have a doubt. After testing, if the resistor is not really needed, you simply remove it on the pcb assembly by removing the resistor from the bom. No raw pcb changes, no ICT tools modification, no blablabla, very small expenses.
But if you don't put it on your schematics, and the resistor is needed, you will have to modify your prototypes, redesign the pcb, modify production tooling, .....which is more expensive, will delay your "start production date".
Angelo