Hellen NB2

Download release firmware

Snapshot firmware bundle

Issue Tracker

Hardware features

  • knock detection module
  • built-in WBO
  • Two auxiliary low side outputs
  • A/C toggle switch
  • A/C relay control

User Support

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Technical Details

schematic rev F Interactive iBom rev F

schematic rev E Interactive iBom rev E

schematic rev D Interactive iBom rev D

schematic rev C Interactive iBom rev C

[rev F Pinout]

rev C-E Pinout

Forum DEVELOPMENT thread

It's Complicated

Mazda Miata 2003 Mazdaspeed Miata 2005



Options Port (rev F)

Using 28 Pin Connector


Pin Type Comments
5P PPS1 Pedal Position Sensor Input 1
5R TPS1 Throttle Position Sensor Input 1
5S TPS2 Throttle Position Sensor Input 1
5T PPS2 Pedal Position Sensor Input 2
5Z WBO Vs/Ip LSU 4.9 Pin 2
5AA WBO Vs LSU 4.9 Pin 6
5AB WBO R Trim LSU 4.9 Pin 5
5AC WBO Ip LSU 4.9 Pin 1
5AD WBO Heater - LSU 4.9 Pin 3
5AE +12v LSU 4.9 Pin 4

*ETB+ and ETB- are on ECU PCB

Jumpers (Applies to board version 72a-72c so far)

in order to run a Miata NB test vehicle:

External MAP vs more ignition channels: a) if you are going to use an external MAP, then remove "R5 (IGN5)", "R7 (IGN6)" and "R11 (IGN8)"

b) or if you NOT using an external MAP (either internal MAP or external MAF, or alpha-N), then remove "R6 (GND)" and "R8 (+5V)"

Warning! The board can be damaged if you skip this step!

External WBO vs more ignition channels: if you want to use an external WBO (AFR) sensor, then remove "R1 (IGN7)"

Miata vehicle type: a) if you have a Miata 2002 (where we measure the battery voltage from 4T=alternator), then remove "R9 (2003)"

b) or if you have a Miata 2003 (where we measure the battery voltage from 4S=ign.switch), then remove "R10 (2002)"

OEM harness add-ons

The OEM ECU connector uses AMP Multilock .040 and .070 pins.

Board stm32 pin
4U MAP Manifold absolute pressure analog signal from external sensor
4K +5v +5v feed for MAP sensor
3Z GND Sensor & USB ground

Proto Area Pinout

Proto stm32 pin

rev C Reference image of jumpers set for external MAP sensor on 2003 miata

See Hellen-WBO