MS3X outputs and acceptable application

[JAM]

I am using many of the MS3x outputs and some of them I am using to ground relays for obvious reasons, however in some cases I do not plan to use a relay, including to turn on/off small LED indicators etc.

I want to make sure I have this right:

the 6 medium current outputs can ground sources up to 3 amp draw
any spare injector outputs I have can ground sources up to 5 amps draw
any spare ignition outputs are pretty much worthless?

[Matt Cramer]

Right on the regular outputs and injectors.

The spare ignition outputs are different critters and source 5V, a few milliamps of it. They can be used as high side drivers for indicator LEDs.

[JAM]

The spare ignition outputs are different critters and source 5V, a few milliamps of it. They can be used as high side drivers for indicator LEDs.

Thanks, so the ignition are a positive output of 5 volts rather than a switch to ground and could run a small LED, the only thing is I do not see ignition outputs in the pull down menus for generic outputs etc.

Any idea what an average VVT solenoid will draw? I have it wired into the standard VVT output which I assume is grounded output 3 amp so I assume it is less draw than 3 amps….?? I guess that should fused to 3 amp so if its greater I should know in a hurry!

[SymTech Laboratories]

Thanks, so the ignition are a positive output of 5 volts rather than a switch to ground and could run a small LED, the only thing is I do not see ignition outputs in the pull down menus for generic outputs etc.

They're there... They look like this: "PB0 - Spk A".

Any idea what an average VVT solenoid will draw? I have it wired into the standard VVT output which I assume is grounded output 3 amp so I assume it is less draw than 3 amps….?? I guess that should fused to 3 amp so if its greater I should know in a hurry!

You can always use an ammeter/multimeter to find out. The medium current outputs will shut down if more than 5A goes through them.

[JAM]

Thanks, so the ignition are a positive output of 5 volts rather than a switch to ground and could run a small LED, the only thing is I do not see ignition outputs in the pull down menus for generic outputs etc.

They're there... They look like this: "PB0 - Spk A".

Ok, my wording was a bit misleading, i was thinking of when you have a pulldown menu for example "SD logger LED indicator " etc does not have spark output as an option or at least I dont recognize it


here is another application. I have a shifter solenoid that always hot, it is 3 amp max draw. the way it fires the shifter is when it is interrupted (break the loop) so a majority of the time it is actually hot to the touch. Is it a bad idea to have something like this running through the megasquirt all the time?

[SymTech Laboratories]

Ok, my wording was a bit misleading, i was thinking of when you have a pulldown menu for example "SD logger LED indicator " etc does not have spark output as an option or at least I dont recognize it

You're right, they're not listed in those instances. They can handle such low amounts of current they're not directly useful for most things, but they can certain handle an LED.

here is another application. I have a shifter solenoid that always hot, it is 3 amp max draw. the way it fires the shifter is when it is interrupted (break the loop) so a majority of the time it is actually hot to the touch. Is it a bad idea to have something like this running through the megasquirt all the time?

We would advise limiting continuous current draw through any of the medium current outputs to 1A or less. More amperage is okay if it's intermittent, but things will start to get hot quickly otherwise. Theoretically, the drivers will increase in temperature by over 170°C if sinking just 3A, which is greater than the absolute maximum temperature for the part.

You might consider using the main board injector drivers if you need to safely sink more current continuously. You should also look at the solenoid's datasheet, or the OEM circuitry if it's an OEM part. Solenoids usually shouldn't get hot to the touch -- it might be a good idea to add an inline resistor.

[JAM]

You might consider using the main board injector drivers if you need to safely sink more current continuously. You should also look at the solenoid's datasheet, or the OEM circuitry if it's an OEM part. Solenoids usually shouldn't get hot to the touch -- it might be a good idea to add an inline resistor.

I was thinking about it being hot and adding a resistor, but not sure how it would work with the solenoid... Ironically there is a label on it that says "caution HOT" so i guess thats just how it works.

I really do not like the fact that it is "hot" and "hot" all the time but I think that it leads to consistent shifts because it actually cocks when the shifter is pulled back and holds rather than energizing to shift which would be dependent on bat voltage etc . I may just go ahead and run it through a relay.

you may find it interesting here is a link http://www.dedenbear.com/TXTshftSOL.htm#ss2

[JAM]

Ok here is another random question:

Any idea how much current the coil side of a standard automotive ice cube relay draws? I was going to use IAC outputs to ground a relay and it looks like they are .5A max current

[kjones6039]

The IAC outputs will drive most automotive relays without any problems..... I use them (the ones you are calling "ice cube") for virtually all of my relay needs.

Ken

[SymTech Laboratories]

Any idea how much current the coil side of a standard automotive ice cube relay draws? I was going to use IAC outputs to ground a relay and it looks like they are .5A max current

They can handle 0.75A, so we agree with kjones6039, they can drive most all automotive relays without a problem (we haven't see many that draw more than about ~200mA each).

[JAM]

Thanks guys. I understand that of the 4 designated iac wires there are 2 outputs, it can be ground or 12v.... which wires are which?

[SymTech Laboratories]

Thanks guys. I understand that of the 4 designated iac wires there are 2 outputs, it can be ground or 12v.... which wires are which?

JS0 and JS2 are typically the pins used for this purpose. You can use JS1 and JS3 too, but they'll always be the opposite of JS0 and JS2 (e.g. JS1 is 0V while JS0 is 12V).

[JAM]

JS0 and JS2 are typically the pins used for this purpose. You can use JS1 and JS3 too, but they'll always be the opposite of JS0 and JS2 (e.g. JS1 is 0V while JS0 is 12V).

Thanks, so it looks like 1B and 2B will be the grounded outputs.

what is this PT4 wire (pin 31) it says logic in/out.... can that be used for a grounded input?? I am needing one more input......

[jsmcortina]

If PT4 is in the dropdown list of pins for the feature you want... then you can use it.

James

[JAM]

If PT4 is in the dropdown list of pins for the feature you want... then you can use it.

James

Thanks James,
So if i select this as an option (it is an option for 3 step input etc.) how do i know if the hardware is set up to take a grounded input or a 12V like on the nitrous?

[SymTech Laboratories]

So if i select this as an option (it is an option for 3 step input etc.) how do i know if the hardware is set up to take a grounded input or a 12V like on the nitrous?

PT4 is practically a direct connection to the processor, so it would be safest to only ground it. You might also need to add a 5V pull-up resistor.

[JAM]

So if i select this as an option (it is an option for 3 step input etc.) how do i know if the hardware is set up to take a grounded input or a 12V like on the nitrous?

PT4 is practically a direct connection to the processor, so it would be safest to only ground it. You might also need to add a 5V pull-up resistor.

How will i now if I need one and where would the resistor need to be installed ?

[SymTech Laboratories]

How will i now if I need one and where would the resistor need to be installed ?

You will need a pull-up if you're using PT4 as an input. A 1k ohm resistor should suffice - just connect it between PT4 and 5V.

[JAM]

You will need a pull-up if you're using PT4 as an input. A 1k ohm resistor should suffice - just connect it between PT4 and 5V.

Thanks for the help. Is this the same procedure if I use "PE2 Flex"

[SymTech Laboratories]

Thanks for the help. Is this the same procedure if I use "PE2 Flex"

FLEX has a 5V pull-up resistor built-in, so you don't need to add one, but you should still be equally careful using it as an input.