AFM-1 connectivity

AFM-1 electrical interface :

This page describes the power and various sensor connections to the AFM-1 instrument.

1) O2 sensor connection (J11) :

The lambda sensor interface of the AFM-1 instrument uses an eight conductor connector located at the bottom of the enclosure. The connector type of the Bosch LSU-4 lambda sensor uses a big 6 conductor connector with built in calibration resistor. Micro-Craft offers an interface cable in several lengths (including custom order length) and for the do-it-yourself community a connector kit.

controller lambda sensor connector pinout

pin-1 : Vref, virtual ground
pin-2 : IPump-out
pin-3 : heater neg
pin-4 : LSU-4 cali
pin-5 : V-sense
pin-6 : heater pos
pin-7 : L1H1 cali
pin-8 : shield ground

Interface cable pics (soon I hope)

2) Auxiliary (J9) and power (J7) connections :

The left connector J9 (green) provides connectivity for RPM signal, three auxiliary 0 to 5 V inputs, two O2 simulation outputs and three wire serial communication interface.

controller main I/O and 12V power connector pinout

Auxiliary connector J9, left green

Power connector J7, white right

The right connector J7 connects the instrument control pos and ground supply and the heater pos and ground supply.

J9.1 : RPM in
J9.2 : RPM ground
J9.3 : aux ch-1 in (0-5V)
J9.4 : aux ch-2 in (0-5V)
J9.5 : aux ch-3 in (0-5V)
J9.6 : aux 5V ref out (50 mA max)
J9.7 : aux and sim ground
J9.8 : sim-1 out
J9.9 : sim-2 out
J9.10 : RS232 ground
J9.11 : RS232 TxD, transmit data
J9.12 : RS232 RxD, receive data

J7.1 heater supply ground
J7.2 heater supply pos (10V to 16V, 5 A)
J7.3 control circuit supply ground
J7.4 control circuit supply pos (10V to 16V, 250 mA)

3) RPM signal connection :

Connect pin 1 of J9 to the primary of the ignition coil. The terminal which connects to the points in the distributor or similar connection on transistorized ignitions. It can also be connected to any source of crank or cam position sensor provided the signal meets the input specs of 12V to 450V.

Connect pin 2 of J9 to an engine or chassis ground near the source of the RPM input signal.

wiring diag pict

wiring diag missing

4) Auxiliary 0 to 5 V input signals :

These three input channels connect to J9 pin 3 to 5, with J9 pin 7 holding the common ground connection. If a signal connects to a sensor which is already connected to a stock EFI (i.e. TPS sensor or MAP sensor), only the signal connection to the sensor needs to be established. The common ground should be connected to the engine or frame ground. If a dedicated (stand alone) sensor is used, J9 pin 6 provides a 5V reference voltage to power the sensor. There is a 50 mA max supply current limit for the 5 V reference signal.

wiring diag pict

wiring diag missing

5) Auxiliary -50 to +75 mV input signals :

Up to eight milli-Volt differential inputs are available on two connectors. The upper connector for ch-5 to cha-8 shown in the picture is optional.
The center pin (5) on each connector provides a ground reference or shield connection.
Each input circuit has 10 k series resistors with a 0.1 uF filter cap.

pin-1 : ch-1 pos
pin-2 : ch-1 neg
pin-3 : ch-2 pos
pin-4 : ch-2 neg
pin-5 : ref or shield ground

pin-6 : ch-3 pos
pin-7 : ch-3 neg
pin-8 : ch-4 pos
pin-9 : ch-4 neg

differential input voltage range = -50 mV to +75 mV
common mode range = 2.0V +/- 1.5V
input impedance = 100 k

6) O2 sensor simulation outputs :

Two pwm controlled analog outputs. J9 pin 8 connect output-1 and J9 pin 9 analog output-2. The common ground reference is on J9 pin 7.
Both outputs have a series current limiting resistor of 100 ohms within the feedback loop of the op-amp. This means that the output voltage is precise, except when it reaches near the 5 V supply or ground level (output current dependent).

wiring diag pict

wiring diag missing

7) Power supply connections :

The AFM-1 instrument is equipped with two independent supply connections.
One, to the internal control circuit.

The other to the sensor heater.

more explanation necessary

wiring diag pict

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