Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

[SOLVED] I need a a-fixed-value-device ?

Status
Not open for further replies.

henninggs

Member level 2
Joined
Nov 10, 2011
Messages
45
Helped
2
Reputation
4
Reaction score
2
Trophy points
1,288
Location
Denmark
Activity points
1,688
I have 4 PCB's with a microcontroller on each. The boards are identically in both hardware and software.
Now when powered on I would like MCU A to run subroutine A, MCU B to run subroutine B and so on. - so I need a way to tell each MCU what to run.

This could be done with at dip switch and a shift register or I could read the value of a resistor. A voltage drop of 0.5v could mean subroutine A, a voltage drop of 1v subroutine B and so on, but this would require that the MCU has a ADC.

If I had a register with a fixed factory-stored value that behaved like a shift register the MCU could just clock the number/value out at start up.
Does such a device exists ? (Need something around 8 bit)

Thanks for any replies.
Regards
 
Last edited:

An easy way to do it without an ADC is to measure the charge/discharge time for an RC-link.
 
Ah that's smart. What is a RC-link exactly ? (I assume it involves a Resistor and a Capacitate)
 

R between VDD and pin and C between pin and GND. For example. Or the other way round (not so common).

Set pin to output, pull low to discharge C, set pin to input, measure time for input to change from 0 to 1. Not very exact but good enough to differentiate between four different versions. Or eight. Or maybe sixteen. Maybe not.
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top