Connecting P2 to LM334Z temperature sensor - MicroPython / Mu demo

Comments

• Tubular Posts: 4,747

  2020-12-22 21:59

  also Emesystems did a great tutorial on constructing small LM334Z probes @"Tracy Allen"
  https://www.emesystems.com/OLDSITE/EarthM/TK334fab.pdf
  
  

  

  

  Eme_LM334Z.png

  1920 x 1080 - 513K

  Eme_LM334Z.png 512.7K
• Tubular Posts: 4,747

  2020-12-22 22:00

  Here's the MicroPython code for putting into Mu
  

  # P2 "Hello LM334Z" MicroPython demo, by Team-oz 23 DEC 2020
  # Hook a LM334z from 3v3 to pin 19. 
  # Tune adjustment resistor to center around 1.65v at temperature of interest, so can zoom in (approx 635 ohms) 
  
  import machine                                                          # machine contains P2 specific functions, eg Pin for I/O pin access
  import time                                                             # time contains time delay routines (sleep)
  
  p=machine.Pin(19)                                                       # our LM334Z is on pin 19
  p.wrpin(p.P_LOW_15K | p.P_ADC_10X| p.P_COUNT_HIGHS | p.P_TT_01  )        # bias the LM334Z with 15k resistor
  p.wxpin(1000000)                                                        # each ADC bucket accumulates for 1 million clocks (~252 Hz)
  p.off()                                                                 # start the current source and observations
  time.sleep_ms(300)                                                      # give it time to get first readings
  
  r=range(121)                                                            # plot 100 readings to Mu plot window
  baseline=p.rdpin()
  print('baseline=' , baseline)                                           # record a baseline ('zero point')
  for i in r:
      print('(',p.rdpin()-baseline,')')                                   # Mu plotted needs values in normal braces to work.  Offset towards zero
      time.sleep_ms(150)                                                  # take around 3 readings per second (expt lasts 30 seconds)
                                                             
  p.float()