CalibraScanner is a derived version of the OpelScanner designed and distributed by http://www.cardiagnostics.tk . Pending works and agreements between Arthur Gyumushyan from Cardiagnostic and Didier Longueville from Club Calibra render the original ECU2PC postponned or obsoleted. The aim of this project is to offer a fully operational diagnostic station based on PC runnning on multiple languages.
Download the trial English version of OpelScanner from http://www.cardiagnostics.tk/.
This interface is fully ISO 9141-1 compliant, cheap and very simple. An LED provides a basic indication on the traffic on the K line: off=idle, blinking=serial date transmitted, steady=trouble(!).
Information from PC flows through the Tx line of the serial comm port and is rectified by D1 in order to prevent negative swings to damage compartor IC1B. Input signals in excess of Vbat will flow through D2, and the current formed is absorbed by R5. This rectified input signal is compared to a reference voltage built across D3 (biased by R8) , in a way that IC1B ouptut is in a high Z state when the input signal exceeds the reference voltage (0 RS232 logical state). So that T1 is biased by R9 and R11 thus shorting R10 to ground. The purpose of R10 is to prevent reciprocal damage to the interface or to external devices. When a 1 RS232 logicial status exists, the input signal is lower than the reference voltage and IC1B output is shorted to ground thus leaving T1 in an open state so that the K line stays at a high level defined by the R4, R12 and R7. The signal input from the K-line is compared to half Vbat (divisor bridge using R1 and R2), in a way that IC1A ouptut is shorted to ground when a high state exists on the K-line, thus creating a low state on the Rx line from the serial port.
All diodes oriented in the same direction. Be carefull with the orientation of IC1 and C1.
The evaluation version of Eagle 1.4 has been used to generate the diagram and PCB. It has a lot of advanced feature even in its freeware version.
Interface cable [S]
Same for the cable: I managed to design and build a simple and affordable male connector for X13 using a simple PCB and some copper wire...