EfiO2Meter SelfTest

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efiO2Meter Self Test

The controller has a few commands to facilitate the testing and calibration and config of the analog inputs TPS and EXT as well as the PWM outputs Analog Out and O2 Simulation.

This works in various ways. One of them being the ability to connect in software the TPS and Ext inputs to the Analog Out and O2 Simulation PWM based outputs.
Another option in software is the direct program-ability of the PWM outputs.

Self Test Commands

Command PTST [cj] [tst] [tim] enables the test mode [tst] for the selected sensor [cj] and [tim] data stream repetition time index.

Self Test Mode 2 and 3 can be used to test drive the PWM output LSUP and LSUD configurations.

Self Test Mode 1

[tst] = 1 : The voltage input at TPS and EXT is output at the Analaog-Out and O2-Simulation PWM outputs. This command enables the Stream Data Output with an added field measured <mVolts>.

 a<2347> ; 1353 ; 921; -309 ; 0 ; 80 ; b ; 955 ; 0 ; 0 ; 0 ; 00 ; 0 ; 4b ; 2d9c6 

a<2347> ; sensor-a display is being used for the TPS to Analog-Out PWM output test.
a<2347> ; 2.347 V are being measured at the TPS input and being output at the PWM Analog-Out.
A typical error should be less than 1.0 % full scale, ideally 0.5 %.
Small Voltages will be more affected by a normal small (typically < 100 mV) PWM output zero offset. This zero offset error can be eliminated by calibrating with the PADJ command. However the effect of the adjust will only show for values above the measured zero offset error.

b<xxxx> ; sensor-b would be used for the EXT to O2-Sim data test connection.

Do not forget to exit PTST [tst=0]

Self Test Mode 2

[tst] = 2 : The voltage input at TPS and EXT (minus 2.5 V to provide negative values) is translated into a simulated Sensor IP-Current and output as the LSUP and LSUD calculated value at the Analog-Out and O2-Simulation PWM output.
In addition additional data fields are output at the Stream Data.

 out-0.0 00894.1435  out-0.1 00894.0000 a<-213> ; 1314 ; 894 ; -431 ; 0 ; 80 ; 8c ; 2da2b  

out-0.0 00894.1435 : out-[TPS=0, EXT=1].[AnalogOut=0, O2Simulation=1] Lambda.mVolt

Do not forget to exit PTST [tst=0]

Self Test Mode 3

[tst] = 3 : This mode provides the ability to precisely specify the desired PWM output voltage using the POUT [cj] [mod] [pwm] command.

[mod] selects the desired pwm units,

  • 0 = pwm raw value 0 - 4095 (12 bit)
  • 1 = pwm volt value on CPU PWM output referenced to the 3.3 V reference voltage (theoretical and not measurable value)
  • 2 = pwm volt value on Sallen Key Active Filter Output, which is the actual POUT and PSIM analog output
  • 3 = pwm data value on Sallen Key Active Filter Output, but in selected Lambda ... O2Percent ... etc ... units, not implemented at this moment, maybe not too useful at all.

POUT .. [pwm] is the desired output value in the POUT .. [mod] selected units.

The correct measurement and calibration procedure would be as follows :

  1. Command PTST [cj] [tst=3].
  2. Command POUT or PSIM [cj] [mod=2] [pwm=0].
  3. Measure Analog-Out or O2-Simulation output voltage and note down as value A.
  4. Command POUT or PSIM [cj] [mod=2] [pwm=A + 50].
  5. Measure Analog-Out or O2-Simulation output voltage.
  6. if measured value is "A + 50" +/- 10 then this PWM output is calibrated.
  7. Otherwise, Command PADJ [cj] [POUT=0 or PSIM=1] [adj = A]

Do not forget to exit PTST [tst=0]

Note : All published design documentation is Copyright efiLabs.com and its use is without exception FOR NON COMMERCIAL PURPOSE ONLY. For commercial licenses contact efilabs.com ... try us, we're reasonable :)

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