Hellen 64 Miata NA6 94

This development board is PnP for NA6 and 94-95 Miatas.

Download release firmware

Snapshot firmware bundle

Interactive Pinout

Issue tracker

Mazda Miata 1990 Schematic

Mazda Miata 1994 Schematic

Hardware features

  • knock detection module
  • build-in WBO
  • battery to keep real time clock running
  • options port for additional I/O

Rev A

Schematic Rev A


Rev B

Schematic Rev B


Extension Pads (rev. b)

Pin Type Comments
P9 PP 1.5 A peak
P10 PP 1.5 A peak
P12 Bridge driver A 3 A peak
P11 Bridge driver A 3 A peak
P13 Bridge driver B 3 A peak
P14 Bridge driver B 3 A peak
P8 Low side 1.4 A
P15 Low side 1 A
P16 Low side 1 A
P17 Low side (always hot) 0.5 A
P18 Low side 0.5 A
P19 Low side 0.5 A
P20 Low side 0.5 A
P21 Low side 0.5 A
P22 High side 4 A
P23 High side 4 A
P24 PP 5 V 20 mA
P25 PP 5 V 20 mA
P29 PP 5 V 20 mA
P30 PP 5 V 20 mA
P31 PP 5 V 20 mA
P32 PP 5 V 20 mA
P1 Knock
P26 Discrete pull down
P27 Discrete pull down
P28 Discrete pull down
P33 Analog pull up
P34 Analog pull up
P35 Analog pull down
P36 Analog pull up
P37 Analog pull up
P38 Analog pull down
P39 Analog pull down
P40 Analog pull up
P41 Analog pull up
P42 Discrete pull up
P43 Discrete pull down
P44 Discrete pull up
P45 Discrete pull down
J4 SPI, UART, I2C, GPIO See silkscreen and schematic for details

Options Port (rev. b)

Pin Type Comments
2A Ground
2B +5v
2C WBO Heater - LSU 4.9 Pin 3
2D +12v LSU 4.9 Pin 4
2E WBO R Trim LSU 4.9 Pin 5
2F WBO Ip LSU 4.9 Pin 1
2G WBO Vs/Ip LSU 4.9 Pin 2
2H WBO Vs LSU 4.9 Pin 6
2I VVT Output
2J Boost Control Output
2K Ground
2L Digital Input Flex Sensor
2M Pressure Sensor
2N Temperature Sensor
2O Ground
2P Knock Sensor Input

Options Port Schematic


Additional Hardware

Options Port Connector

LSU 4.9 Wideband Connector

LSU 4.9 Wideband Sensor Or Similar