measure ohm of HS15P

Dependencies:   mbed

Fork of Frequency_counter by Neel Shah

This test program measures ohm of HS15P, humidity sensor.


C(micro F) with LMC5550.

If you get 2500 microseconds as interrupt time interval , it means 18 kilo ohm when 0.1 micro F. ( = 2500 * 0.0072 )

  • ohm of HS15P is calculated from pulse interval of LMC555.
    • CONV_KILO_OHM will be used.
  • this program reads interval time.between interrupt in the P8.
  • takes ON the P9 to oscillate LMC555 as short as enough to measure interval time
  • last several interval times will be used for calculation.
    • the time is defined as READ_TIMER .
  • In current circit, VDD of LMC555 is about 1.55V, AC 0.4V between pins of HS15P.
    • LMC555 consumes 120 micro A while oscillation, 90 micro A when level of P9 is OFF. (reset is ON)
    • Total 1-2mA is consumed in the circit.

Related nootbook :

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Files at revision 8:6d956be23ed8

Name Size Actions
main.cpp 1603 Revisions Annotate
main.h 548 Revisions Annotate
mbed.bld 65 Revisions Annotate