Resistors

delene · Joined: 13 Oct 2003 Posts: 32

If I have one load cell connected to my board I want to use this resistor value and enable pin_a0.
If I have two load cells connected to my board, I want to this resistor value and enable pin_a1.
And the same if I have 3, 4, 6 or 8 load cells connected.

Is it possible to use io lines to determine which resistors are enable/used?
If not, what can I use to do this?

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

Why can't you just record the information in a variable ? You could
have a bitmask variable (one byte) that is a copy of PortA. When you
set Pin A0 high, then set bit 0 in the variable to 1. When you set Pin A0
low, then set bit 0 in the variable to 0.

What PIC are you using ? (Always post your PIC, because the answer
can be different, depending on your PIC).

SherpaDoug · Joined: 07 Sep 2003 Posts: 1640 Location: Cape Cod Mass USA

I am not sure I understand your problem, but this may help. If you want to pick one of several resistors to connect from a node to either PIC VDD or VSS, you can connect all the resistors to PIC I/O pins. Then set all the pins to Hi-Z except the pin for the resistor you want which you set to 1 or 0. The other resistors will be floating at the PIC end and effectively out of the circuit. Just make sure the unused resistor voltages are OK for the PIC pins.
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