Additional components for GenBoard/VerThree when bought from WebShop

This is a bit old, apparently from the very first v3.0 series. Most stuff is now (v3.3) onboard by standard (on the non-assembled board too). So mostly a review list for the curious, not a todo list.

Note that at most places there is a huge range of good values (eg. supply caps' capacitance). V3.1 has basically everything installed (except the FETs and IGBTs) that is needed to run an engine fuel, WBO2 and spark, but you probably want to review what does what. And maybe you want knocksensing, EGT



Note that this section is according to one's taste. Some leave out the fuse, transient suppression diode, inductor and does not install extra caps. Others just make a small section from a very thin wire as a fuse. Some people install a lot of supply filtering. Unfortunately the high voltage ramp of the ignition switching (unless you put ignition modules close to the coil on plug transformers) emit some electromagnetic radiation from the wires, no matter how well the supply is filtered.

Recommended setup - this is appropriate in many cases, ask from experts (first put on your MembersPage) if you're not sure

Only issue before v3.2:

for serial port' see GenBoard/Manual/CommHardware

Needed for MAP sensor:

R12 10k
C10 100nF - 10k and 100nF RC filter (10k * 100nF = 1 msec)
C11 min: 0,1uF (220nF - 2.2 uF?)
Cextra10 Optional The [MPX4250A datasheet] suggests a small cap on output of MAP - (pin1=MAP_SIGNAL) to +5V (no individual pads, but easy to put a 0805 SMD cap there) there's a huge range of good values though, use 470pF..1nF if you have (but max 100nF). The datasheet says to GND, but doesn't matter for a cap if it goes to VCC or GND. Except at powerup: it's better if it goes to VCC [AN1646 Noise Considerations]
MAP signal (U2-pin1) is often connected to EC18-pin3 when the sensor is not mounted onboard (electronic connection instead of case-mounted pressure-fitting).

Needed for Temp sensors:

The best value for these depend on your actual sensors: 2.2 .. 2.7k are usually OK. Some bias can be corrected with easytherm perfectly. It is a very good idea to check operation anyway, so you better calibrate if you are there.

R9 2,49k for CLT
R10 2,49k for MAT
V3.2, Both of these resistors are soldered when you get the board, 2.7k

Needed for primary and secondary trigger: See


Needed for ExhaustGasTemp: see GenBoard/Manual/ExhaustGasTemp

Needed for acoustic knock sensing:

See GenBoard/Manual/KnockSensor

Needed for IGN:

Ignition IGBT
R22, R40, R41, R42, R64 R96, R122, R123 (these gate resistors are preinstalled)
V3.2, Solder the IGBT's only

NOT Needed for IGN:

D11, D18, D19, D20, D26, D30, D33, D34 (leave open)

Injector section

Check out GenBoard/Manual/DDFlyback

Needed for INJ, DR FlyBack suggested:

D7, D8, D10, D16, D17, D25, D28, D29 (S2J) You want to connect the flyrail to the positive(+) of injectors (no fuse or switch in between!!)
R18, R21, R36, R39, R60, R63, R92, R95 (33 Ohm resistors recommended with FETdrivers; max 1k gate resistors without FETdriver, but no PWMing than)
Check out GenBoard/VerThree/LowZInjectors
U3, U6, U8, U9 (when not using FETdrivers, short pin 2 to pin 7 and pin 4 to pin 5 at every place)

Normally using diodes or short here, NOT resistors, check GenBoard/Manual/DDFlyback

R19, R20, R37, R38, R61, R62, R93, R94 (just short these to 0 ohm)
Q19, C61, D32, R121 (leave them open)

V3.2, Solder the missing flyback diodes, check GenBoard/Manual/DDFlyback and don't forget the wire from flybackrail to EC36

Needed for 1st channel WBO2:

This part should be dropped, because duplicates GenBoard/Installation/WBOconnect?

R51 510ohm (Pump1+)
R102 75k (Nernst_Cell1) Do not solder this, if you have only a NarrowBand oxygene sensor!
R133 10k (Heater 1)
R134 1k (Heater 1)
Q18 FET Transistor (Heater 1)
V3.2, Only solder the Q18 FET

Needed for TPS

The variable resistor type TPS sensor needs GND and +5V input so it can emit an output signal between 0..5V (real range is often just 1..3V, but don't worry, it's configurable). The simpler throttle-idle-switch only requires GND, but that is not a real TPS anyway.

populate R142 (270 ohm) and C69 (220 nF) which makes a current-limited supply for your TPS. These (R142 and C69) are not automatically populated on V32 either, since some people uses this EC36 pin for other purposes (eg. input pin) and applies an "offboard R142" in the wiring for the TPS.
Refrain from using the HALL5V signal directly unless absolutely needed (eg. for HALL sensor supply). Especially avoid shorting it to GND (the onboard 78L05 limits to 100mA and it might survive for some time, but it's not guaranteed).

Needed for bipolar stepper motor control

Stepper chip (DIP16) L293NE or SN754410
if you want inductive load on stepper lines (not unlikely, eg. stepper motor is inductive) you want to short the diode D45 (which powers the stepper chip) with 2.5 .. 5A fuse (or with some experience a thin wire ~ poor man's fuse) parallel with a reverse populated D45 (yes! anode on the stepper chip side).
8 x S2.. stepper flyback diodes on the bottom. Only required for L293NE (that is not sold in WebShop for a long time now), not necessary for the common SN754410 as SN754410 has internal clamping. For L293NE make absolutely sure the 8 pieces of S2.. diodes at the bottom side of the stepper driver are soldered in (only possible on v3.0 or v3.1, pads removed from v3.2). If you drive resistive load, these flyback diodes are not needed, since the resistive load will not activate the FlyBack (but the inductive will).

Not Needed:

R5 PEN on AtMega
C49 Fuel Pressure
even the reset circuit (wether RC or MCP809 type) can be dropped (the AVR has internal brown-out protection, and pullup on reset line)

Recommended checklist for v3.3

Applies for genboard v3.3 sent out before 2006.jan.20. For nonassembled, recommended to check regardless the time of sending out.

This changes to AREF=256 (from AREF=287):


Same, but in another perspective:


And on v3.2, there are pads for the component, but solder a 0 Ohm resistor or small thin wire (eg. one hair from a stranded wire). Some tests indicate that 0 Ohm or small wire is better than 33 Ohm if the GND5 sees high current and voltage fluctuations (usually because of directly driven ignition coils).


I only removed endplate on mine. The capacitor endcap is easy to solder to. Scratch the solderprotect from the end 6..7 mm of the longer 5V trace to solder to.

The modification effects:

This small resistor powers AVCC-AVR. Without this, it is powered by a diode inside the AVR (it was an unintentional change in v3.3) giving a voltage drop (that can be compensated with configuration).

Note that AREF is powered from inside the AVR (using a setting in firmware) from the AVCC-AVR (and just needs decoupling cap on the external pin). This is OK this way. This seems to have confused hw-designers somewhat about the AVCC.

See also