I am building a shield for an arduino UNO that contains a DS1337+. The schematics below is a [very] simplified version:
(several components, like crystal, omitted for brevity)
U1 is the arduino shield itself, with pins directly connecting to the arduino UNO.
What I am planning is to have 2 jumpers connecting - or not - the DS1337's INTA and INTB to the arduino's interrupt ports (D2 and D3). According to the DS1337 datasheet, the INTA and INTB ports are open drain outputs, and require and external pullup resistor. Thus my questions:
1) What are the good values for the pullup resistors?
2) Is it possible to use a single resistor for both ports or does each one need its own resistor?
3) JMP1 is the jumper (they will be pin headers, not dip switches) that will either enable or disable the use of the interrupts but the arduino, because another shield might require those 2 ports on the arduino. If JMP1 has both lines open, the INTA and INTB ports in the DS1337 wiill be getting some voltage from the arduino. Is that ok? Can these 2 ports receive the voltage without being connected to anything else?
Thanks in advance.