Re: My core board & I/O board design, need your comments
Posted: Sat Feb 04, 2012 8:49 pm
Fred had asked for me to give your project a once over, so here goes:
Based on your commit with Hash: 42c7c0b346bbd1a60e1466cb79e18170f2867ce7
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On catsquirt.sch:
C1, C2, C3, C5, C9, C10 should be 0.22uF/50v X7R Ceramic capacitor
C2 should have a parallel 10uF/10v Tantalum capacitor
C3 should have a parallel 10uF/10v Tantalum capacitor
Consider changing the PLL values to Fred's recommended values:
R1 3.3k
C6 6.8nF
C7 680pF
For the crystal, if you choose the same ECS HC-49US:
C4 and C8 can be anywhere from 12pF to 22pF, just need to make sure the crystal oscillates.
On the BDM, consider changing R6 from 4.7k to 10k to reduce the number of different values of resistors. The value really isn't critical from my testing.
I'm guessing from the rest of the schematics in your project file that catsquirt.sch was for a prototype board before you started working on the mainboard.sch as the actual board to use on your car.
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It appears that catsquirt.sch and prototype.sch are also other prototype boards.
I would recommend removing catsquirt.sch and prototype.sch from your project file as they make it a little confusing to figure out which one you are developing for your car versus what you are using on your test bench.
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On Core Board.sch:
It appears that you have been keeping up with my Jaguar board, which is good as Fred, Dan and TonyS and I have been working out the details and I am very close to etching a prototype board to test on my car...
It also appears that some of the libraries that you used don't exist on my PC since they show up as boxes with ?? in them when I look at this schematic, but could be that I don't have your library loaded.
C24, C39, C42, C46, C47 and C50 should be a Tantalum capacitor as electrolytics don't last very long in high temperature applications.
C46 on your schematic should be changed to 47uF/10v Tantalum as I have changed it on my schematic to match your equivalent of C50.
R12 could be 1M or 10M, not sure which is correct. Technological Arts used a 10M resistor and so did I on my prototype board and I am considering changing to a 10M resistor on the Jaguar board as well.
For the crystal, if you choose the same ECS HC-49US:
C17 and C21 can be anywhere from 12pF to 22pF, just need to make sure the crystal oscillates.
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On VR Interfaces.sch:
Make sure that R63 and R65 are 1/2W resistors, and I recommend using a 1W resistor for R28.
I recommend than you use a 2.4k 1/4W resistor for R29, but if this causes an issue with your RPM input to the CPU then you can always remove it.
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U_Core Analogue Inputs.sch looks good except for the boxes with ?? in them, but could be that I don't have your library loaded.
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On Low Side Drivers.sch and Injectors.sch:
Consider changing from VNP10N07 (100mOhm On-State Resistance, rated 70v @ 10A) to VNP14NV04 (35mOhm On-State Resistance, rated 40v @ 18A). This change will result in less heat generated while the device is in an "ON" state. They both have the same pinout so they are direct drop-in replacements.
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For U_Ignitor Outputs.sch I don't have much useful information as I haven't looked at driving ignitors for my board.
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I would like to find out more information about your circuit on U_Dashboard Analogue Outputs.sch as this could be helpful for my Jaguar board to supply a usable Tachometer output to run the dash tachometer for GM vehicles with DIS ignition.
Let me know if you have any questions about my comments as I may have been less than clear about the reasoning for them.
Based on your commit with Hash: 42c7c0b346bbd1a60e1466cb79e18170f2867ce7
-----
On catsquirt.sch:
C1, C2, C3, C5, C9, C10 should be 0.22uF/50v X7R Ceramic capacitor
C2 should have a parallel 10uF/10v Tantalum capacitor
C3 should have a parallel 10uF/10v Tantalum capacitor
Consider changing the PLL values to Fred's recommended values:
R1 3.3k
C6 6.8nF
C7 680pF
For the crystal, if you choose the same ECS HC-49US:
C4 and C8 can be anywhere from 12pF to 22pF, just need to make sure the crystal oscillates.
On the BDM, consider changing R6 from 4.7k to 10k to reduce the number of different values of resistors. The value really isn't critical from my testing.
I'm guessing from the rest of the schematics in your project file that catsquirt.sch was for a prototype board before you started working on the mainboard.sch as the actual board to use on your car.
-----
It appears that catsquirt.sch and prototype.sch are also other prototype boards.
I would recommend removing catsquirt.sch and prototype.sch from your project file as they make it a little confusing to figure out which one you are developing for your car versus what you are using on your test bench.
-----
On Core Board.sch:
It appears that you have been keeping up with my Jaguar board, which is good as Fred, Dan and TonyS and I have been working out the details and I am very close to etching a prototype board to test on my car...
It also appears that some of the libraries that you used don't exist on my PC since they show up as boxes with ?? in them when I look at this schematic, but could be that I don't have your library loaded.
C24, C39, C42, C46, C47 and C50 should be a Tantalum capacitor as electrolytics don't last very long in high temperature applications.
C46 on your schematic should be changed to 47uF/10v Tantalum as I have changed it on my schematic to match your equivalent of C50.
R12 could be 1M or 10M, not sure which is correct. Technological Arts used a 10M resistor and so did I on my prototype board and I am considering changing to a 10M resistor on the Jaguar board as well.
For the crystal, if you choose the same ECS HC-49US:
C17 and C21 can be anywhere from 12pF to 22pF, just need to make sure the crystal oscillates.
-----
On VR Interfaces.sch:
Make sure that R63 and R65 are 1/2W resistors, and I recommend using a 1W resistor for R28.
I recommend than you use a 2.4k 1/4W resistor for R29, but if this causes an issue with your RPM input to the CPU then you can always remove it.
-----
U_Core Analogue Inputs.sch looks good except for the boxes with ?? in them, but could be that I don't have your library loaded.
-----
On Low Side Drivers.sch and Injectors.sch:
Consider changing from VNP10N07 (100mOhm On-State Resistance, rated 70v @ 10A) to VNP14NV04 (35mOhm On-State Resistance, rated 40v @ 18A). This change will result in less heat generated while the device is in an "ON" state. They both have the same pinout so they are direct drop-in replacements.
-----
For U_Ignitor Outputs.sch I don't have much useful information as I haven't looked at driving ignitors for my board.
-----
I would like to find out more information about your circuit on U_Dashboard Analogue Outputs.sch as this could be helpful for my Jaguar board to supply a usable Tachometer output to run the dash tachometer for GM vehicles with DIS ignition.
Let me know if you have any questions about my comments as I may have been less than clear about the reasoning for them.