###     
  ##     
  ##     
  #####  
  ##  ## 
  ##  ## 
 ######  
         

         
         
 ##  ##  
 ##  ##  
 ##  ##  
  #####  
    ##   
 ####    

         
         
  ####   
 #    #  
 #    #  
 #    #  
  ####   
         

      #  
      #  
  ### #  
 #   ##  
 #    #  
 #   ##  
  ### #  
         

         
|\     /|
| )   ( |
| |   | |
( (   ) )
 \ \_/ / 
  \   /  
   \_/   
         

IMPORTANT: enter the case-INsensitive alphabetic (no numbers) code AND WRITE SOME SHORT summary of changes (below) if you are saving changes. (not required for previewing changes). Wiki-spamming is not tolerated, will be removed, so it does NOT even show up in history. Spammers go away now.


Visit Preferences to set your user name
Summary of change:
Make a '''test circuit''' (cheap 2 resistors used instead of the LSU4 sensor) for initial WBO2 PID tuning: * Rppn=100 Ohm between pump+ and nernst * Rnpm=100 Ohm between nernst and pump- That's all. This way the current "pump" (current generator) is tested, which is an important part of the WBO2 circuit. You can measure the resulting nernst voltage (with DVM, DC voltage mode): Over Rnpm, Urnpm=appr. 450 mV (400..490mV) should be measured. ----- * ok lets work out the combinations.. Urnpm, Rnpm does not mean much, except to the firmware folks.. possibilties. With a stock board and the 12x12 default setup I get, (with the board triggered running @ 1200RPM) Signal hookup... Pump- (100Ohm) Nernst (100Ohm) Pump+ Resultant Voltages... Pump- --> Pump+ '''0.415V''' Nernst --> Pump- '''0.210V''' Nernst --> Pump+ '''0.205V''' Gnd --> Nernst '''4.18V''' Gnd --> Pump- '''3.97V''' Gnd --> Pump+ '''4.38V''' Now which of these measurements is important? How do I adjust the values to make it right? What should the default values be for a LSU4 setup? In fact you can disturb the circuit by changing the resistors to some degree, or connect a resistor (like 1..10k) between nernst and GND (or between nernst and 5V). The (faked) lambda reading will change, but the Urnpm=appr. 450 mV should hold. '''Reading is slightly off, say pump- is 3.98V (relative to GND) and Unernst=4.3V (relative to GND) instead of 4.43V. How can it be tuned?''' * wbo2_pump_pid_kd=00 (I doubt that any other value makes sense) * wbo2_pump_pid_kp=20..40 ... too high value will result in significant oscillation. * '''nernst_dc_target ''' adjusts above mentioned Urnpm (target-value). If other factors are OK, the target nernst DC voltage (ideally Upump- + 450mV) can be directly set with this. Adjust until OK. * Make sure the multiple '''wbo2_pump_pid_ki * wbo2_pump_pid_ilimit''' is high enough. If this is too low, pump+ will be limited: as a result, nernst_dc_target can not always be reached. ** I revised a theoretical reasonable maximum for the multiple : '''wbo2_pump_pid_ki * wbo2_pump_pid_ilimit''' (sg. like 0x80 * 0x0A) but that might be off a few bits (dunno where I got it wrong): ** in practice this multiple was not enough to raise pump command sufficiently (from 0x63 to FF) so I had to use higher, appr. '''0x80 * 0x40''' values. ** While the multiple value is the most important, for same multiple value, the PID integral term operation will be faster for lower pump_pid_ilimit (and necessarily higher wbo2_pump_pid_ki, so the multiple remains same) Don't connect real sensor until PID (and nernst_dc_target) is tuned with that so nernst is stable and fine (450mV above pump- ). [http://megasquirtavr.sourceforge.net/manual/Detailed.Sensor.Wide.html#Install [Detailed.Sensor.Wide.Install]] ---- '''Go back to:''' GenBoard/Manual/WBSensor GenBoard/Manual
Optional: Add document to category:
Wiki formatting: * is Bullet list ** Bullet list subentry ... '''Bold''', ---- is horizontal ruler, <code> preformatted text... </code> See wiki editing HELP for tables and other formatting tips and tricks.