Project JAGuar for FreeEMS

[Fred]

Cool. Disregard other post.

[DeuceEFI]

Cool. Disregard other post.

Fire Department slang here would say "Signal 9", which means to disregard the last transmission, or in Navy terms, belay.

[TonyS]

OK, Comments are in no particular order or importance, I'll just submit em as I think about em.

1. Damn Andy, you are one fast and furious designer : )
2. I think that its GREAT that the individual Digikey part numbers on the BOM have embedded links to the parts, but it might be helpful to others if the mfg and mfg P/N were shown on the BOM also.
3. The pdfs of the board layout and silkscreens don't render correctly in my version of Acrobat reader (all I get is readable text).
4. Unfortunately, the schematic pdfs are not searchable, which leads to -
5. I can't tell (or initially find) how "5V-switched" or "5vdc-micro" nets from the power supplies sheet matches up with the "VDD", "VCC", "5vdc-analog",.. on the CPU sheet.

Enough for this post, but I'll keep looking

[Fred]

+1 on 1. and 2. :-)

[TonyS]

6. BOM calls out a crystal with 20pF load capacitors, but schematic and BOM indicate 18pF caps are being used (not sure of the impact).
7. 10k resistors on the VR inputs are only a 1/4W per the BOM. Your call, but they may over-dissipate (see my comments in the thread you reference in your VR note). Hmmm, I'm wondering why is there a 5k resistor on the VR inputs?
8. The MAP sensor power supply de-coupling and output filtering doesn't seem to match what is in the datasheet for this part or the general application note referenced in the datasheet (not sure of the impact).
9. On the power supply sheet, there are two identical regulators with different bulk capacitors.
10. The BOM seems to have at least a couple of instances in which the same type/value part is on two different rows. You also may want to see if can can substitute parts with similar values to one common value/part.

that's all for tonight

[DeuceEFI]

OK, Comments are in no particular order or importance, I'll just submit em as I think about em.

1. Damn Andy, you are one fast and furious designer : )

Thanks, I have had plenty of time to think about my design, but most of it was based on projects that never got very far, so with Dan and Fred's help I have gotten my design to this point fairly quickly

2. I think that its GREAT that the individual Digikey part numbers on the BOM have embedded links to the parts, but it might be helpful to others if the mfg and mfg P/N were shown on the BOM also.

Sounds reasonable, so I have added them to the BOM.

3. The pdfs of the board layout and silkscreens don't render correctly in my version of Acrobat reader (all I get is readable text).

I created those with the PDF printer on my Debian 6 workstation, I will use the Winblows7 machine from now on for the PDF creation...

4. Unfortunately, the schematic pdfs are not searchable, which leads to -
5. I can't tell (or initially find) how "5V-switched" or "5vdc-micro" nets from the power supplies sheet matches up with the "VDD", "VCC", "5vdc-analog",.. on the CPU sheet.

I have changed the names of the nets from "5vdc-micro" to 5vdc-cpu (which = VDD) and 5vdc-switch / 5vdc-switched to 5vdc-analog (which = VCC). Hopefully this will help

[DeuceEFI]

6. BOM calls out a crystal with 20pF load capacitors, but schematic and BOM indicate 18pF caps are being used (not sure of the impact).

You will probably find that you cant get a nice 16MHz crystal that requires 22pF load caps. 18pF/12pF is probably a better choice for crystal availability.

Hence the 18pF caps instead of 22pF...

7. 10k resistors on the VR inputs are only a 1/4W per the BOM. Your call, but they may over-dissipate (see my comments in the thread you reference in your VR note). Hmmm, I'm wondering why is there a 5k resistor on the VR inputs?

I copied the same circuit from the Ravage.PDF file and those were the values that appear. I'm not using the VR sensor input, I'm using a Hall Effect sensor for my Crank and Cam sensors, so if this needs to be changed, just let me know

8. The MAP sensor power supply de-coupling and output filtering doesn't seem to match what is in the datasheet for this part or the general application note referenced in the datasheet (not sure of the impact).

Here again this is the same circuit in the Ravage.PDF file...

9. On the power supply sheet, there are two identical regulators with different bulk capacitors.

Fred and I have discussed this in past posts and determined that having a large cap before the CPU isn't necessary since the regulator is close to the CPU.

10. The BOM seems to have at least a couple of instances in which the same type/value part is on two different rows. You also may want to see if can can substitute parts with similar values to one common value/part.

Ok, I see the 10uF Tantalum on Row 3 and Row 9... FIXED

There is a case of a 1k 1% resistor and a 1.0k 0.1% resistor but there is no need for the expense for the 0.1% resistor ($0.44 each) where the 1% resistors ($0.13 each) are used. There are multiple resistances for the R24, R25 and R26 resistors based on the temperature sending units the user wishes to use or already has on their engine. The user only needs to buy and install the 3 resistors that match the manufacturer of their sensors, then calibrate using FreeTherm.

All files affected by the above changes have been commited...
hash = f7a9f09099ab52fe3d71d5038650764739d69651

[DeuceEFI]

+1 on 1. and 2.

I am motivated to see this work on my V-6 in the Deuce, will definately be a YouTube moment to see flames shoot out the headers...

[TonyS]

Hi Andy,

6. BOM calls out a crystal with 20pF load capacitors, but schematic and BOM indicate 18pF caps are being used (not sure of the impact).

You will probably find that you cant get a nice 16MHz crystal that requires 22pF load caps. 18pF/12pF is probably a better choice for crystal availability.

Hence the 18pF caps instead of 22pF...

Hopefully a better description of my concern -
The mfg's specifications for the crystal that is on the BOM, specifies 20pF load capacitors (which in my opinion is what should be used). The load capacitors may / will be different for other 16MHz crystals depending on the mfg, mounting type, series,... I really don't see a good reason to use anything other than what the mfg's spec for this specific crystal says to use.

7. 10k resistors on the VR inputs are only a 1/4W per the BOM. Your call, but they may over-dissipate (see my comments in the thread you reference in your VR note). Hmmm, I'm wondering why is there a 5k resistor on the VR inputs?

I copied the same circuit from the Ravage.PDF file and those were the values that appear. I'm not using the VR sensor input, I'm using a Hall Effect sensor for my Crank and Cam sensors, so if this needs to be changed, just let me know

There is currently only a schematic for Ravage, which specifies a 10k resistor (correct), but a BOM has not been created yet so the wattage of the part is unknown (which is why I am still on sheet 1 of my Ravage review : ) But in your case, a 1/4W resistor was called out so I am concerned that this dissipation is not enough for the application (my concerns are related in the noted thread). Since you are using Hall sensors, really doesn't apply, but may impact others who would use your board with VR type sensors. Which brings up another comment / suggestion - should there should be a way to "jumper" around the MAX9926 sub-circuit for Hall only applications so you don't have to populate the VR stuff?

8. The MAP sensor power supply de-coupling and output filtering doesn't seem to match what is in the datasheet for this part or the general application note referenced in the datasheet (not sure of the impact).

Here again this is the same circuit in the Ravage.PDF file...

I think that the "inputs" on Ravage are still to be reviewed by Fred (others), but either way, I am just pointing out my concern and will leave it at that.

9. On the power supply sheet, there are two identical regulators with different bulk capacitors.

Fred and I have discussed this in past posts and determined that having a large cap before the CPU isn't necessary since the regulator is close to the CPU.

10. The BOM seems to have at least a couple of instances in which the same type/value part is on two different rows. You also may want to see if can can substitute parts with similar values to one common value/part.

The point I was trying to make is that you might want to review the BOM, and make changes to the schematic design to minimize the number of unique part types on the BOM. For example, do you want to have one 22uF and one 47uF cap on your design/BOM or two 47uF (you also might want to consider 10V parts as they appear to be considerably cheaper). Why specify a single 2k resistor (R55) whose only function appears to be a pull-up (can't you just use another 2.4k?). Are three different de-bug LED colors needed if you are going to put the board in a case? Can you substitute another 10uF/35V cap for the single 4.7uF/10V?
Also, note that C23 and C42 are the same part, but on two different rowsl

Please don't interpret my comments as being written in a negative way, I think you are doing a GREAT job but unfortunately I write my comments after a long day at work and after a few (quite a few : ) beverages.

Thanks,
Huff

[TonyS]

Haven't passed out yet so -
11. You may want to consider connecting VDDA on the uC to VCC instead of VDD.
12. You may want to consider connecting the Check Engine Light sub-circuit to VDD instead of VCC (it really doesn't have much to do with the analog stuff).
13. Can you use a single 5V regulator instead of two since you aren't planning on using the "always on" topology?

Thanks,
Huff