V3 to send a linear wideband output signal to a 3rd party device
Page title is misleading: originally it was narrowband sensor emulation, but wideband output is also possible of course
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- Round is frequently used to send out analog (or PWM) WBO2 data (or "emulated narrowband")
- MembersPage/ToyotaPriusLpg since Prius ECU likes a bit fluctuating NBO2 signal (around 0.45V around 1.0 lambda), that is also implemented as a special case
- v3 is rarely used to send out analog (or PWM) because usually v3 controls itself, and v3 can send out in digital form with CRC protection (AIM format, or VEMS triggerframe format, or 2nd serial modbus slave RS485 or RS232 connection : with custom compiled fw used in powerplants; modbus master is also possible but that is really special, not normally used)
V3 with lambda output was used in Fefe's Lada Samara which historically had 3 ECU:
- factory gasoline
- +addon LPG
- vems v3 ECU for logging, and cheated nbo2 output:
Fefe's HW had a 5V output and a voltage divider of 5.7: 1k/(1k+4.7k)
- Max rich 255
- Stoich 131 (0.45V)
- Max lean Y=0 (0V)
- as this was implemented with an internal 17 point table called narrowband_out (and interpolation), it is easy to change to other curve (linear is also easy).
It was a bit special, we need to check how it can be configured currently (possibly adding some config options is justified ?).
It seems to be still active if NBO2_OUT is defined in my_make..., as PWM on S259_OUT2 output. This pin is inside VEMS v3, on the s259 chip.
- With NBO2_OUT firmware ... can you confirm (with DVM, or scope) the PWM signal changes as lambda goes richer /leaner than 1.0 ?
- Order ECU with order comment: "S259_OUT2 connected to output (preferrably with some RC filter) for lambda output"
- this is inside ECU, a pin of the 74HC259D SOIC16 chip that controls stepper (it is NOT the same as the ETC PWM signal !)
An OEM ECU in this case. This can already be done with a Round
display, but as discussed, this would be possible to do with a
custom (or new standard with some new options) firmware on the V3 as well. If possible we would like to get
the same signal that the round can send on the analog output when
vout_conf=5, which is a wideband high resolution linear output
(0..5V) There is really no need for any configuration options for
this, everything can be hardcoded if such feature is not wanted in the main-line firmware.
This v3 ECU (serialnr... ) has two EGT sensors however egt2 reads 30C higher
even when testing outside of the car. Giving a constant heat for the thermocouple then switching it from egt1 to egt2 in
the harness, gives an instant increase of the reading by 30C.
However the difference is not linear, the issue manifests over around 300degC.
The given calibration is for EGT1, but egt2 should be very close (definitely much closer than 30C).
Can you check the sensor cable ground connection ?
Possible options:
- VT ini
- resistor outside
- resistor inside
hint: Connect the same calibrator or K-thermocouple to both inputs simultaneously, and take note of some actual readings to see the calibration curve.