Microsquirt V3 - no spark on IGN1

[jnovak]

Following the paper trail here...

Just setup a new Microsquirt V3. Configured with a Hall sensor triggered by magnetic wheel. Single magnet per cylinder - basic trigger configuration. Get a very stable signal in TS.

output IGN1 set in tigger options and connected to MSD 6AL. This should be a logic level input.

There is no output to IGN1 as verified with my scope.

Some documentation says to use a BIP transistor driver on the board. Do I need this? Do I need a pull-up. Please point me to the manual description for this. Having a hard time with documentation.

[jsmcortina]

The manuals for Microsquirt are under the "Manuals" link above. You want the Microsquirt Hardware manual. Connecting the MSD to the IGN1 output may have damaged your Microsquirt.

James

[jnovak]

Been in the manuals. following this... From Section 5.3

5.3 Ignition outputs

The Microsquirt as standard provides two logic ignition channels. Optionally the WLED and ALED outputs can
be re-purposed to give a total of four channels.

The logic outputs are suitable for connection to logic coils or ignition amplifier modules. Do not directly connect
high-current coils.

The MSD is an ignition amplifier. It usually takes a logic trigger from points or optical. I have run them like this on MS2.

Is WLED a better choice? This is buried in a footnote on a figure following Section 5.3.

So, this should work according to the documentation. Please explain how I may have damaged the unit? have not seen anything about this.

[jsmcortina]

See section 5.3.4

You might have damaged the Microsquirt if you connected the MSD white wire to IGN1. The white wire (input) puts out 12V. The IGN1 output on the Microsquirt is not designed to accept 12V.

James

[jnovak]

James,

Thank you for the reference.

Is there any documentation on what is damaged using IGN1? Is this CPU damage or external componentry? So far, everything seems to be working besides not having a spark output.

Will check WLED tomorrow and see if it will trigger the scope.

[jnovak]

Switched wiring and software to WLED and spark is working now.

Thanks.

[dontz125]

Is there any documentation on what is damaged using IGN1? Is this CPU damage or external componentry?

The schematic in the uS Hardware manual shows a 100 Ohm series resistor between the IGNOUT header pin and the IGN processor pin, as well as a 100k pull-down and a BAT54 shunt diode. My old textbook says power dissipated through a resistor = V x V / R; putting 12V (nominal) across a 100 Ohm resistor gives ~ 1.4 W. The actual voltage and power was probably higher.

Looking at the Mouser website, most resistors of that physical size (0805 or smaller) are in the 0.1-0.5W range, so (hopefully!) that resistor popped pretty quick, acting as a fuse and protecting the processor pin. You'll have to remove various screws holding everything together and take a look. The fact that WLED is working is a positive sign, but it is possible to burn one pin - or a trace - and leave the rest of the unit intact.