WBo₂ 2C0 (original) Wideband

The 2C0 is Tech Edge's miniature wideband product. Although We designed it for motorcycle use where its small size is important, it can be used in most situations where accuracy is important, but the on-board logging facilities of other units is not required.

2C0 uses an M16 processor and has the more sophisticated pump cell control technology that is found in the newer version 3 WBo2 units. It has a 12 bit hardware DAC with differential wideband output (WBlin+ & WBlin-). note: 2C0 (original) does NOT work with the LSU 4.9 sensor (the newer 2C0B does), but it does work with the NTK UEGO sensor. This controller is a faster and more apgrade upgrade from the economy 2J1 model (although 2C0 doesn't have some of that model's extra input capability, but the newer 2C0B unit does).

Tech Edge  2C0 Features

• Accuracy within 0.1 AFR (Lambda +/- 0.005).
• 12 bit differential WBlin output.
• 10.5 to 19.5 Volt DC operation (up to 3 Amps).
• Supports LSU 4.0/4.2 (Bosch 6066/7057 family) as well as NTK (L1H1/L2H2) sensor (requires NTK sensor cable).
• NB_sim narrowband output (10 bit PWM signal & configurable too).
• SV_out 10 bit configurable (for LD01 display too).
• RPM input from Tacho or ECU for logging.

The image at left shows how 2C0 is connected to other WBo2 wideband components. Some popup images of parts are available.

Clockwise from the bottom right, the LSU (UEGO support may be offered later) sensor is connected via the sensor cable (comes in various lengths for different applications). The sensor cable's circular 8 pin connector mates with the 2C0 unit. 2C0 needs a source of power provided by the two pin power cable.

On the back of the case are an 8 pin (RJ45), and a 6 pin (RJ11) connector for PC RS232 connectivity (config & logging) and for connection to an intelligent display. The top of the case carries three status LEDs that show power (GREEN), heater (AMBER) and operational (RED) status.

The side of the case carries a 6 pin green unpluggable connector with voltage outputs and RPM logging inputs.

The connectors and their inputs & outputs are described in detail below. Also see the brief connector summary.

Front of 2C0, Y3 & Y2.

Side of 2C0, Y4.

Back of 2C0, Y1A & Y1B.

WB_lin+ Pin 1/Y4 & WB_lin- Pin 2/Y4 Wideband Output

The most accurate of the 3 voltage outputs is WB_lin which is generated by a 12 bit DAC using a 65 word lookup table (with linear interpolation). A special feature of 2C0's WB_lin is what we have called a differential output which is designed to reduce the amount of noise and possible voltage offset errors seen by a device connected to WBlin. The WBlin differential output is described fully here. WBlin can be re-programmed using the Config utility to cover any part of the AFR range from Lambda = 0.6 to free-air and 0 to 5 Volt output.

Note that pin 4/Y1A (8 pin RJ45) also carries the WB_lin+ signal, but remember that the WB_lin-GND shunt (see details) should be installed if this single ended output is used instead of the differential +/- output.

The default linear wideband output mapping is shown in the image at right.

To convert the default WBlin voltage to an AFR simply multiply the measured voltage by 2 and add 9. This is shown in the graph at left. The advantage of a linear output is that it's easy to write a conversion function from the wideband voltage to AFR.

SV_out Pin 5/Y1B (5 on RJ45) Compatibility Output

To generate SV_out, the processor uses a 65 word lookup table with linear interpolation. It converts the normalised pump current (Ipx) into a 10 bit value representing SVout. A hardware PWM (Pulse Width Modulation) pin on the processor generates the actual SVout voltage.

SVout is compatible with the Vout signal from the original oz-diy-wb unit (and the 1.5 unit's Vwb). It can be used to drive the analogue LD01 display (or the older 5301 if you change its connector). Note that the 12 bit WBlin can be re-programmed to use the SVout table, so if you're not using WBlin and you want a more accurate SVout voltage, you should consider reprogramming WBlin. Remember however that SVout covers the full range of full-rich (Lambda=0.6) to free-air, the voltage range is small (less than 3 Volts) so measuring resolution is reduced compared to using a smaller AFR range over a larger voltage range.

The default SVout, shown at right, varies between about 1.0 Volt for a very rich mixture (Lambda=0.6 or AFR=9), to 2.50 Volts for a stoic mixture, and to 3.1 Volts for a lean mixture (AFR=25). In free-air the SVout should be exactly 4.00 Volts when the unit has been free-air calibrated correctly.

The default AFR vs. SVout relationship is shown in the Vout table/graph page. The analogue Vout is a continuously available signal that may be logged with a high speed logger. We recommend at least a 10 bit converter for best accuracy.

NB_sim Pin 4/Y4 Simulated Narrowband Output

A synthesized narrowband (NB_sim) voltage is produced by the onboard microcontroller using a 10 bit A/D PWM converter (with single pole filter), and a 65 word lookup table. Linear interpolation improves lookup accuracy. The full 0 to 5 Volt output is available, but restricting the output to 0 to 1 volt reduces the number of possible steps to around 200 (~5 mV per step).

As well as pin 4 of the green connector (Y4), pin 6/Y1A (8 pin RJ45) also carries the NB_sim signal.

The NB output is designed to be compatible with the raw output of a Bosch LSM-11 sensor. Refer to this eXcel spreadsheet for the graph of the default NBsim vs AFR.

As NBsim can re-programmed it is possible to do a number of interesting things such as fooling the engine's ECU (if equipped with a NB sensor) into running richer or leaner than it would do otherwise.

The 2C0's RJ45 connector (left black 8 pin connector) carries RS232 and other signals. The unit transmits logged data on its Tx line [pin 3 - RJ45] and receives commands (from PC or display) and code updates from a PC on its Rx line [pin 2 - RJ45].

The diagram at left shows the wires within the cable and also the connections at each end. Note the pin names change from left to right - the WB unit's Tx pin transmits to the PC's Rx pin (and vice versa). [pin 5 - RJ45] is the shield for the Rx and Tx data lines as well as being the return data path.

WBo2 to PC cable

Here's an image of the actual RS232 cable for connection between a PC and the WB unit. The cable is used for either logging to a PC, or for re-flashing its code (under control of a PC). If you need to extend the cable then a standard straight through male-female DB9 extension cable should be used (ie. not a cross-over or null modem cable).

The SV_out [pin 1], WB_lin+ [pin 4] & NB_sim [pin 6] signals are all described in detail above. The SV_out signal is intended for analogue displays like the LD01 and those displays will also use Vbatt & GND described below. The RJ45 connector signal names are shown at right.

A fused, protected and partially filtered battery voltage V_batt is available from [pin 8] (right most RJ45 signal). This output is provided to power other devices such as the LD02 display. It should only be connected to devices that will draw small currents; typically less than 100 milliamps. Excessive current consumption may cause heating of an internal dropping/protection resistor.

A ground GND point [pin 5-RJ45] is provided as a return for the RS232 and Vbatt connections.

Note that there are number of unconnected outputs (N/C = No Connection) on each of the RJ-45 connectors. Those N/C's that have uses on other wideband units are shown "greyed in" and include WBlin (pin 4) and NBsim (pin 6).

6 Pin RJ11 Connector - LSS T_x & R_x, also SV_out, WB_lin+, GND & V_batt

The right hand side RJ11 connector is designed for use with an intelligent serial display. Its primary feature is a second serial channel called the Low Speed Serial (LSS) interface which has a 1200 baud data rate (ie. low speed) which is adequate for most displays. Additionally there are duplicates signals found on the RJ45 and green 6 pin connector.

Tacho Input - RPM_coil (Pin 7/10) & RPM_lo (Pin 8/10)

2C0 has a single RPM channel that is captured for logging. Two inputs are provided, one for direct connection to a COIL (or a Tach signal as generated by some vehicles) and another for a lower voltage "logic level" signal as is generated by some sensors. Only one of the RPM inputs can be used at one time. The image at right (click for popup enlargement) shows the location of VR1 inside the 2C0 case. VR1 can be adjusted to reject high frequency noise signals that sometimes interfere with RPM capture.

The RPM COIL input [pin 7/10] normally connects to the wire going between the points and the COIL. On vehicles that have electronic ignition and a distributor, you would connect to the point between the transistor switch (or ignition amplifier) and the coil. The COIL input should never be connected to any voltage larger than 12 Volts or damage to the WBo2 unit may result.

The RPM Lo input [pin 8/10] can be connected to any lower voltage signal that produces a 5 volt pulse at some small multiple of the engine's revs. Unfortunately the loading (low input impedance) of the Lo input sometimes makes it infeasible to connect to sensitive circuits such as an inductive crank angle sensor.

Operation of the LEDs (Power, Heater, Status)

The unit has three LEDs. Their Normal operational status is described below. From left to right the LEDs are :

• GREEN = Power LED indicates power is connected. It should never be flashing.
  
  
• AMBER = Heater Power LED shows the level of power being supplied to the sensor's heater. It should flicker reasonably brightly at 30 Hz.
  
  
• RED = Status LED flashes while the sensor is warming up, to indicate error conditions, and to indicating on-board logging status.

Diagnostics from the RED & AMBER LEDs

Normal Operation : The unit should always have a steady RED LED (unless on-board logging is active - see below). The AMBER LED is brightly LIT but will flicker at 30 Hz (just perceptible). The intensity of the AMBER flicker will give some idea of how much power is being used to maintain the heater's temperature.

Normal - Heating : Just after the unit has been turned on the normal heating cycle will cause the RED LED to flash about once a second with a short sharp ON time, and longer OFF time. The AMBER LED will produce a small amount of flicker (30 Hz), but should be brightly LIT. This should last 20 to 30 seconds for a cold sensor. If the time is much over 30 seconds then either the battery voltage may be low or the sensor is placed where it is being excessively cooled by the gas flowing past it. A cool sensor position may result in reduced sensor life and inaccurate measurements.

Error - No Heating : If the sensor cable is disconnected or damaged, the battery voltage too low or too high, or some other problem with the heater circuit occurs, the RED LED will flash with a fast regular ON - OFF beat twice a second While these conditions remain the AMBER LED will be mostly DIM but will produce a very sharp flicker a few times a second (the unit is looking for sensor or sampling battery voltage). This condition can occur during starting or when there is excessive battery drain during idle. It may be an indication of a poor battery or alternator/regulator, or connection to the wrong point of the vehicle's wiring.

Unlocked PID : It's possible for transient conditions to cause the RED LED to flash off briefly. As long as the AMBER LED and green POWER LED remain on then this is an indication of a PID unlock condition.

A PID unlock is not necessarily an error, but it does indicate either very rapid changes in heating or cooling of the sensor, and/or rapid changes in the ambient air-fuel ratio. If this occurs without an explanation (such as rapid changes in throttle position) then it may be an indication of an intermittent somewhere in the wiring, or an aging sensor. Both the LD02 and the TEWBlog logger indicate these conditions.

The heater PID sharp single OFF flash is shown and prior to rev firmware Rev-48 this single OFF flash was also used to indicate a wideband PID unlock too. This condition indicates may indicate the sensor is positioned where it is either too hot or too cool.

A wideband PID is now indicated by a sharp double OFF flash as shown here. If you have earlier firmware and need to differentiate between the two conditions then download the latest HXF flash files and update (note, all 2A0 files start with version number 00).

2C0 does not store data on-board like other WBo2 models. But a serial data stream is available to be logged to a PC or other RS232 device. Win32 and other platform Logging software is available right now.