Puma board for FreeEMS

[Fred]

Additionally, the USB LEDs don't work because they are grounded and they are supposed to be connected to VCCIO... I've cut the arse out of the via for grounding them, and have to connect it up to the power feed, and misappropriate a couple of LEDs from the fuel output channels and fit a few resistors and I'll have blinking LEDs when comms are active. I don't care too much, but that is the issue with your board, Marcos.

[jharvey]

Here's the quick and dirty schematic;

Looks like KICAD, is this something you can post such that we can use it on a larger connector card? The connector card would have the typical ECU connector, perhaps the Jim Stim interface, ect. I'm not a CAN expert, it locks good to me. Thanks for pursuing it.

[KW1252]

Here's the quick and dirty schematic;

Looks like KICAD, is this something you can post such that we can use it on a larger connector card? The connector card would have the typical ECU connector, perhaps the Jim Stim interface, ect. I'm not a CAN expert, it locks good to me. Thanks for pursuing it.

Sure, I'll just fix the annotations first, clean up some stuff and add comments. Then I'll either attach it here or look into GIT options.

[jharvey]

Marco's, I think I found a way to combine all those digi protects and an protects, while maintaining the current option and ability to be copied into other spins. I just checked in a copy with a modified top level sheet that includes the key piece I hadn't thought of before. Look how I split EGT_IN from the other AN protects, but used on common lower level sheet. I'm confident this will allow the other protects to be brought into one sheet, however there is some risk it can break nets and such. So I'm putting at the end of the list, just before the Vreg thing.

As a quick recap, the schematic has many pages with only a couple parts on them. This was done such that future spins were easy to copy. While this isn't really a problem to navigate for folks that have some really basic KICAD skills, the generated 50+ PDF / hard copy pages is a bit of a pain to work with. I think I just figured out how to combine about 21 pages into one page. This should make it much easier to navigate on paper.

Also I like your idea of using the switching Vreg to generate something like a 7V signal, then use the linear to make a 5V. Get's us energy efficient ripple free power supply. The only down side I can think of, is an extra couple pennies in parts.

[Fred]

(21:22:07) fredcooke1: nitrousnrg__: what does "added reset monitor" mean?
(21:28:24) nitrousnrg__: it drives the reset pin in an intelligent way, at the same cost of a 10uf capacitor
(21:28:58) nitrousnrg__: until i figure out why the board isn't starting correctly, it stays
(21:29:13) ***nitrousnrg__ zzz...

Marcos, you should have *A* capacitor on there regardless, it's VERY good practice, IE, part of the future hardware spec, I'm unsure what an appropriate size is (probably small is fine), but it should be protected by a cap to avoid induced resets.

Fred.

[nitrousnrg]

The device is this:
http://ww1.microchip.com/downloads/en/D ... 21661d.pdf

It won't reset the MCU unless VDD goes under 4.63v for more than 140msec. The datasheet doesn't suggest a capacitor, in fact, it mention that some devices may want a pulldown to discharge capacitances in the reset line.

re the power switching supply:
Pros of having it:
* More efficiency, less heat in the linear regulators
* regulators can provide a ripple-free 5v. This should be checked, though.
* board could operate down to 4.4v if we use the L5970, for example

Cons:
* More components = more $, more space
* one more thing that can fail
* there is a 250khz switching device in the board

Sure, it can fail, but if the regulators are operating 20°C cooler, the overall reliability is better.

[Fred]

The device is this:
http://ww1.microchip.com/downloads/en/D ... 21661d.pdf

It won't reset the MCU unless VDD goes under 4.63v for more than 140msec.

Fine probably.

The datasheet doesn't suggest a capacitor, in fact, it mention that some devices may want a pulldown to discharge capacitances in the reset line.

The datasheet doesn't, I fucking do!!! Don't ignore years of hands on practical experience... I don't just say these things for fun...

re the power switching supply:

The board already operates down to 4.4v AS IS

Pros of having it:
* More efficiency, less heat in the linear regulators
* regulators can provide a ripple-free 5v. This should be checked, though.

Cons:
* More components = more $, more space
* one more thing that can fail
* there is a 250khz switching device in the board
* it deviates EVEN further from the original design and, combined with all the other necessary change, puts spin 2 almost back where spin 1 started..

Sure, it can fail, but if the regulators are operating 20°C cooler, the overall reliability is better.

[/quote]

Fixed. Am I wasting my time writing things? It seems like you totally ignored what I said about functional V levels.

[nitrousnrg]

Don't ignore years of hands on practical experience

I'm not ignoring you, but if the datasheet says so, I'm sticking to it. The IC expects a high impedance in its output, who knows what can happen if I put a source of low impedance there. They made the thing man.

The board already operates down to 4.4v AS IS

It doesnt.
The MCU is alive, so is the USB, but the analog circuitry and sensors behaves as shit. It is not an operative voltage. Its also not a big deal, I want this regulator because of a temperature issue, not because of the supply voltage.

it deviates EVEN further from the original design and, combined with all the other necessary change, puts spin 2 almost back where spin 1 started

* What? its only an addition. In the very worst situation it can be bypassed, and its easy to test that mod in a spin1 board. We are FAR from where we were by the time spin1 was born.
* There is no such original design, if it has problems it needs to be corrected now. The aim of spin1 was to prove that the core circuits were functioning, it fabrication was rushed because of my time constraints, and I'm ok with that.
I see no point in producing a board that stops working at 75°C.

"functional V levels"? You mean the time when you were having a bad time cranking the car? I recall it wasn't an direct voltage issue, maybe its because of some transient, although I doubt that (you have many capacitors in the board and i don't).

Have to go, byebye

[nitrousnrg]

I've jharvey's BOM here, so I'm answering some questions raised about it:

Items of question

* C95
Is a 0.1uF, why?
* Mic2954:
It has 250mA vs 400mA of the LM2937. The last seems like a safer choice.
* low side drive mosfets
totally optional, they're insanely huge (RFP30N06). Perhaps you guys have a better/cheaper/more common suggestion?
* R151 and R150
Yeah, that circuit was taken from a Bosch sensor datasheet, for the thermistor that my car and quite a bunch of other cars here have. Those resistors aren't part of a normal setup. Ask fred about the values of the bias resistor, it should be calculated with Freetherm afaik.
* SEE ROW 59 AND COLUM AR???:
Umm, no?

I see I mixed a .1uF with a 0.1uF in my BOM, good you corrected it in yours (they are the same but appears twice). Also there is a 5.1v that is the same as 5v1, they're zeners.

Also, I see items with a "???" in the NOTES column. Mostly regarding P&H stuff and other minor changes.
Whats the doubt about P&H? The circuit need some track cutting, but is buildable.
There is a diode (1N4448) in exchange of a smaller one (1N4148) that wouldn't work in that place. Anyway, A few commits ago I realized that I can put schottky, so instead of 1N4448 there should be another schottky :-)

SWVreg appears as a recommended item, if it is the little circuit to shutdown the 5v reg, I wouldn't recommend it. Its so not-proven.

O2 has no extra components but the protection circuits, which has some RC filtering. I'd remove the filtering caps at the circuit protection (in all channels), and only filter in the input circuitry. Maybe having diodes so close to the ADC can make the input too noisy, I can check that in minutes.

I'm about to count the components as a second check

Again, fantastic work jharvey!

[jharvey]

* C95
Is a 0.1uF, why?

Sorry Crossed eyes and time constrained, I didn't notice 100nF as .1uF. Also I updated the 10nF.

* Mic2954:
It has 250mA vs 400mA of the LM2937. The last seems like a safer choice.

Updated and no longer in ?

* low side drive mosfets
totally optional, they're insanely huge (RFP30N06). Perhaps you guys have a better/cheaper/more common suggestion?

I'm not crazy about that choice, I changed to VNP20N07 an OVP MOSFET.

* R151 and R150
Yeah, that circuit was taken from a Bosch sensor datasheet, for the thermistor that my car and quite a bunch of other cars here have. Those resistors aren't part of a normal setup. Ask fred about the values of the bias resistor, it should be calculated with Freetherm afaik.

The issue is that I didn't have an exact match value. I'm guessing you used 39K and 3.3K.

Also, I see items with a "???" in the NOTES column. Mostly regarding P&H stuff and other minor changes.

Ooops, just noticed those components and updated. Sorry crossed eyed. The ??? meant total qty for that part was 0. So not orders and ???

There is a diode (1N4448) in exchange of a smaller one (1N4148) that wouldn't work in that place. Anyway, A few commits ago I realized that I can put schottky, so instead of 1N4448 there should be another schottky

??? So 1N4148 is now a different diode We should update the schematic to call for a different diode.

SWVreg appears as a recommended item, if it is the little circuit to shutdown the 5v reg, I wouldn't recommend it. Its so not-proven.

SW was a place older for SWithing V Regulator. it doesn't have parts yet, so it wouldn't be populated.

O2 has no extra components but the protection circuits, which has some RC filtering. I'd remove the filtering caps at the circuit protection (in all channels), and only filter in the input circuitry. Maybe having diodes so close to the ADC can make the input too noisy, I can check that in minutes.

This being a qty 0, could be a good thing. The diodes and cap should basically not influence the circuit unless you exceed the frequency or voltage of the circuit. I should QUCS this circuit to show it's reactions a bit better. A down side is that I can't figure out how to do a FFT with the copy of QUCS I have.

I'm about to count the components as a second check

I just updated it, and moved some things around. I think it should be all set, but there is a chance things shifted up a row or two. So it should be double checked.

Again, fantastic work jharvey!

Thanks.

Here's what I see that needs addressing.

R150 and R151 are exact values, but are probably really 39K and 3.3K, what should they be?
1R1W and 1R should these be the same? I probably have a buggered count, the are currently 1R.
1N4448 is replaced by a different diode, but what one?
C21 470pF and C123 1uF doesn't appear in the BOM. What's the digikey/MFG number?

Newest BOM pushed.