Cinchdogs LSx board design......
Posted: Wed Oct 01, 2014 8:26 am
Hi all, I am new to this forum and still trying to play catch up on the progress of free ems. Since hardware design is where i feel i can contribute the most, i thought this thread the best place to start.
I have designed and built quite a few Custom PCB boards, ranging from Audio amplifiers to specialized industrial instrumentation to, gasp, custom one off MS type boards.
Most have worked just fine, some suffered design flaws and were well learned lessons on what not to do .
I have looked at some of the proposed/developed I/O boards and Karri's Wildcat would seem to be the closest to what I would like to do, however I want to design a board that goes a bit further.
What i am thinking is an upscale version of a board that i am currently working on, that uses "another" micro controller, however that chip has limited I/O pins and is limited to 4 injector drivers and 4 Spark signals with only a couple extra I/O.
What it does have is a very small footprint and a water proof automotive connector, look up JAE MX23A34, its a readily available and a fairly cheep, compact connector.
What the free EMS might allow me to do, is to expand on my current design to allow 8 injector driver and 8 spark outputs, as well as a host of spare I/O pins for general purpose.
It would probably not be a "do all", as the MX23 series connectors are only rated a 3amps per pin, direct coil control would probably lead to failures, and low Z injectors might also overload the pins. That is not to say that using multiple pins to carry the load is out of the question, MS has used that scheme and it appears to work fine for them. In any case, this was the reason behind the proposed name, the LSx uses modern injectors with high impedance, and utilizes coil packs with built in drivers, so this board would be a good fit for such an instillation. Plus, I think keeping the high voltage stuff near the coils and away from signal lines is always a good idea.
But the idea behind this is very much in line with the Modice style enclosure, mainly something that will be waterproof and small. I like the idea of mounting the ECM under the hood ( in a smart location of course ) and not having to run the entire wiring harness through the firewall. The draw back to this is it does require higher temp rated components, but that isn't a huge issue.
The board I am currently working on that uses the other micro is very compact, about 65mm x 40mm and will use a custom machined aluminum case mated to the ground plane to act as a heat sink. I resigned to designing this after a few failed attempts to put an MS based system on my motorcycle, that has almost no room for anything bigger. I did get it running, but even with an uncased microsquirt module and a DIY JAW, it was a sloppy install and no case for the MS module was a fatal flaw. I played with it for a few weeks but pulled it off because it was mot a question of if, but when it would leave me stranded.
Still some testing to do on a prototype board, and i am sure i will need to tweak a few things, but i see no real reason that this couldn't be scaled up a bit and use the larger micro and a second connector.
I have designed and built quite a few Custom PCB boards, ranging from Audio amplifiers to specialized industrial instrumentation to, gasp, custom one off MS type boards.
Most have worked just fine, some suffered design flaws and were well learned lessons on what not to do .
I have looked at some of the proposed/developed I/O boards and Karri's Wildcat would seem to be the closest to what I would like to do, however I want to design a board that goes a bit further.
What i am thinking is an upscale version of a board that i am currently working on, that uses "another" micro controller, however that chip has limited I/O pins and is limited to 4 injector drivers and 4 Spark signals with only a couple extra I/O.
What it does have is a very small footprint and a water proof automotive connector, look up JAE MX23A34, its a readily available and a fairly cheep, compact connector.
What the free EMS might allow me to do, is to expand on my current design to allow 8 injector driver and 8 spark outputs, as well as a host of spare I/O pins for general purpose.
It would probably not be a "do all", as the MX23 series connectors are only rated a 3amps per pin, direct coil control would probably lead to failures, and low Z injectors might also overload the pins. That is not to say that using multiple pins to carry the load is out of the question, MS has used that scheme and it appears to work fine for them. In any case, this was the reason behind the proposed name, the LSx uses modern injectors with high impedance, and utilizes coil packs with built in drivers, so this board would be a good fit for such an instillation. Plus, I think keeping the high voltage stuff near the coils and away from signal lines is always a good idea.
But the idea behind this is very much in line with the Modice style enclosure, mainly something that will be waterproof and small. I like the idea of mounting the ECM under the hood ( in a smart location of course ) and not having to run the entire wiring harness through the firewall. The draw back to this is it does require higher temp rated components, but that isn't a huge issue.
The board I am currently working on that uses the other micro is very compact, about 65mm x 40mm and will use a custom machined aluminum case mated to the ground plane to act as a heat sink. I resigned to designing this after a few failed attempts to put an MS based system on my motorcycle, that has almost no room for anything bigger. I did get it running, but even with an uncased microsquirt module and a DIY JAW, it was a sloppy install and no case for the MS module was a fatal flaw. I played with it for a few weeks but pulled it off because it was mot a question of if, but when it would leave me stranded.
Still some testing to do on a prototype board, and i am sure i will need to tweak a few things, but i see no real reason that this couldn't be scaled up a bit and use the larger micro and a second connector.