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How to calculate resistance value from RC time — Parallax Forums

How to calculate resistance value from RC time

chenguanyannchenguanyann Posts: 15
edited 2011-09-06 08:33 in Propeller 1
Connection diagram is as follows:
P=Propoller chip I/O Pin

　 R=220Ω C=30pf
P ────┳────── GND
　　　　│
　 ┌───  Rx=0Ω~20MΩ
　 │　　 │
　 └───┻───── GND

I can get the RCTime from it. How to calculate the resistance value "Rx" from value of RCTime?
RCTIME.spin
spin
spin
RCTIME.spin
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Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2011-09-05 19:35
    Download and read the Basic Stamp Syntax and Reference Manual. There's a section on the RCTIME statement beginning around page 363 that discusses this. The Propeller's switching threshold is about 1/2 of Vdd, so normally that would be about 1.65V. Also look at the Wikipedia starting with this page.
  • RS_JimRS_Jim Posts: 1,773
    edited 2011-09-06 08:33
    There is some software in the PE_funbook that does resistance measurement and even shows you how to calabrate the results.
    Jim
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