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Arttu's MS3 compatible processor board 
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Joined: Mon Dec 10, 2012 10:10 am
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This project has been on my to-do list for long time. Actually I discussed about this with Fred over a year ago and there is some discussion about the idea in this thread: viewtopic.php?f=9&t=2044 But as it usually happens this got buried under other more urgent tasks but now I think it's time to get something done.

So the basic idea is to make a FreeEMS processor board that is more or less compatible with MS3. The goal is that current MS3 users can swap to FreeEMS as easily as possible. I hope this would expand potential user, tester and developer base significantly.

At the moment I have the first revision of the schematics ready and it's available there: http://www.iki.fi/arttuh/FreeEMS/freeems_uc_board.pdf
I have used mainly Jaguar and Ravage schematics as reference for IO pin mappings and other similar details. If anyone cares to spend some time to review the schematics I would appreciate it greatly. All feedback is welcome.

I noticed the Ravage supports a quite large set of features but I'm bit unsure if they all are supported in current (or near future) firmware. Any way, I prefer to add support for as many features as possible on my board if there is any chance that they will be implemented in firmware in future, especially if existing HW support increases changes to get support in firmware too ;) But it would be nice if Fred or someone else could comment about status of following features:
-Support for I2C RTC chip
-Support for TPIC8101 knock sensor interface
-CAN bus, any plans to use it for something?
-SD card for logging or something else
-Support for multiple or alternative serial ports. For example by using the USB-serial bridge as tuning connection if there is something connected and otherwise using the second port with RS232 or BT connection.


Last edited by Arttu on Wed Sep 10, 2014 9:08 am, edited 1 time in total.



Tue Aug 19, 2014 12:31 pm
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Arttu wrote:
I noticed the Ravage supports a quite large set of features but I'm bit unsure if they all are supported in current (or near future) firmware.

Some of it is a chicken-egg issue, and the other main issue is that there are much more major things that are NOT good enough with the firmware that need addressing. The number of people capable of addressing those things seems to be exactly one ;-) Though offers to do non-essential stuff are always plentiful.

Arttu wrote:
Any way, I prefer to add support for as many features as possible on my board if there is any chance that they will be implemented in firmware in future, especially if existing HW support increases changes to get support in firmware too ;)

It absolutely does by removing the chicken-egg issue and making it a firmware only issue.

Arttu wrote:
But it would be nice if Fred or someone else could comment about status of following features:
-Support for I2C RTC chip Nothing yet, should be easy, but requires the always-on stuff to be working, and that's not easy, at all
-Support for TPIC8101 knock sensor interface Nothing yet, should be easy, requires hw and time
-CAN bus, any plans to use it for something? Some work done, use is likely to be a configurable thing, with various implementations switchable
-SD card for logging or something else Spudmn was keen to do this, and did some work toward it, I'm unsure how performant it would be, but it'd be useful regardless
-Support for multiple or alternative serial ports. For example by using the USB-serial bridge as tuning connection if there is something connected and otherwise using the second port with RS232 or BT connection.Various uses, depending on the nature of the connectivity. I had an idea to add hw switchable RX connectivity so you can choose to control the device with BT OR USB but not both, and listen on both always. Allows logging independent of the tuning functionality. Code used to support more than one serial on the default interface, but I ripped it out years ago.

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Tue Aug 19, 2014 10:59 pm
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Nice, thanks. It sounds like I will keep all planned features in the design since any of them isn't completely out of the question for FW development. Unfortunately I can't offer much help for FW development but I hope that better availability of HW will attract more developers to get involved.

Arttu wrote:
-Support for I2C RTC chip Nothing yet, should be easy, but requires the always-on stuff to be working, and that's not easy, at all

Hmm, I was thinking of battery backed RTC chip. That shouldn't need any additional always-on functionality, right?

Quote:
-Support for multiple or alternative serial ports. For example by using the USB-serial bridge as tuning connection if there is something connected and otherwise using the second port with RS232 or BT connection.Various uses, depending on the nature of the connectivity. I had an idea to add hw switchable RX connectivity so you can choose to control the device with BT OR USB but not both, and listen on both always. Allows logging independent of the tuning functionality. Code used to support more than one serial on the default interface, but I ripped it out years ago.

Yes, that's pretty much what I was thinking of. Is there any fundamental problems with using two serial ports in the code? I think it would be more flexible and simple than using one port with HW switching.


Wed Aug 20, 2014 10:23 am
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Arttu wrote:
Hmm, I was thinking of battery backed RTC chip. That shouldn't need any additional always-on functionality, right?

Ahh, fair enough, I guess. Just seems to me that there is this HUGE battery right there :-) Baby steps, though, and maybe selectable modes.

Arttu wrote:
Yes, that's pretty much what I was thinking of. Is there any fundamental problems with using two serial ports in the code? I think it would be more flexible and simple than using one port with HW switching.

No, it's not difficult, however I want to gut that code and make it a lot more modular. It is robust and fast and works well, but there is a lot of duplication and it's very procedural.

Fred.

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Wed Aug 20, 2014 8:37 pm
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All right, the lay-out is pretty much ready now. If there aren't any last moment change suggestions I will send the board files to manufacturing soon.

The schematic has been changed a bit too. The main change is addition of few jumpers to allow routing of ignition and injector signals to the MS main board through DIP40 socket. So this enables using the processor board with a basic MS main board, i.e. without MS3X output board.

Updated schematic: http://www.iki.fi/arttuh/FreeEMS/freeem ... rd_v09.pdf
Component placement top and bottom:
http://www.iki.fi/arttuh/FreeEMS/top.pdf
http://www.iki.fi/arttuh/FreeEMS/bottom.pdf


Wed Sep 10, 2014 9:18 am
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Arttu wrote:
All right, the lay-out is pretty much ready now. If there aren't any last moment change suggestions I will send the board files to manufacturing soon.

Hold on there for a minute, Ghost Rider, I wouldn't jump into manufacturing so soon...

Here is a small list that I see needs attention before having the PCB manufactured:
  • You need to look at my Jaguar schematics again for the power supply capacitors for VDDX, VDDR1, VDD1, VDD2, VDDA and VRH, what you have is very WRONG and backwards. You should also be using 0.22uF capacitors rather than 0.1uF capacitors on these circuits per the 9S12XDP512 datasheet.
  • You have the connections to the ADUM1201 backwards, again look at the Jaguar schematic. The way your schematic shows you won't have any serial communications.
  • You don't have any way to load the firmware via the serial monitor/serial port/USB since you have no Load/CEL circuitry for Port A6.
  • On your CANTX pull up resistor you show a strong pull up with a 1k ohm, change that to a weaker pull up 10k resistor.
  • Your USB LEDs are going to be very bright, I recommend using 470 ohm resistors instead of the 330 ohm.

Once you address those issues, which are in order of the severity of the error, post your schematic back up and I'll review further.

Cheers,

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Wed Sep 10, 2014 1:28 pm
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Why don't you build up your project based on mine ?

https://github.com/ruzki/Free_EMS_Board_ruzki


Wed Sep 10, 2014 7:47 pm
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DeuceEFI wrote:
Hold on there for a minute, Ghost Rider, I wouldn't jump into manufacturing so soon...


Hi, thanks for the feedback. It's always good to get someone else to check your work as you are often blind to your own mistakes.
Quote:
Here is a small list that I see needs attention before having the PCB manufactured:
  • You need to look at my Jaguar schematics again for the power supply capacitors for VDDX, VDDR1, VDD1, VDD2, VDDA and VRH, what you have is very WRONG and backwards. You should also be using 0.22uF capacitors rather than 0.1uF capacitors on these circuits per the 9S12XDP512 datasheet.

Could you explain a bit more what is wrong? I double checked these against the Jaguar schematic and the datasheet and didn't spot anything. As far as I can see these are connected exactly the same than on the Jaguar. I changed the 100nF capacitors to 220nF.
Quote:
  • You have the connections to the ADUM1201 backwards, again look at the Jaguar schematic. The way your schematic shows you won't have any serial communications.

  • Ha! Good old RX/TX/IN/OUT mishap :) Not first time I did that and surely not the last. On my defense I have to say I copied this form the Jaguar 0.6-alpha schematic. ;) Fixed.
    Quote:
  • You don't have any way to load the firmware via the serial monitor/serial port/USB since you have no Load/CEL circuitry for Port A6.

  • Thanks for noting. Somehow I forgot this in the middle of work. Added.
    Quote:
  • On your CANTX pull up resistor you show a strong pull up with a 1k ohm, change that to a weaker pull up 10k resistor.

  • Changed.
    Quote:
  • Your USB LEDs are going to be very bright, I recommend using 470 ohm resistors instead of the 330 ohm.

  • Hmm. 330 ohm would result roughly 9 mA led current and 470 ohm about 6 mA. Both are fine IMO and brightness will depend more on the LED. Changed them any way.

    Quote:
    Once you address those issues, which are in order of the severity of the error, post your schematic back up and I'll review further.


    I updated the schematic in the link above. Thanks again for taking a look on this.


    Thu Sep 11, 2014 6:34 am
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    ruzki wrote:
    Why don't you build up your project based on mine ?

    https://github.com/ruzki/Free_EMS_Board_ruzki


    Hi Ruzki,

    Yes, our boards indeed kind of overlap each other. There were few reasons why I still decided to design my own:
    -I wanted to add support for all features available on MS3X board. Or on other more sophisticated compatible main boards ;)
    -When I committed to proceed with this your project seemed to be quite inactive and I wasn't sure if it was going to be available for others.
    -I like designing electronic gadgets :)

    Btw, is there schematics for your board in pdf format somewhere?


    Thu Sep 11, 2014 6:49 am
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    Quote:
    -I wanted to add support for all features available on MS3X board. Or on other more sophisticated compatible main boards ;)

    You are free to modify the Board as you want .. and i think it is easier to start with this Board.

    Quote:
    -When I committed to proceed with this your project seemed to be quite inactive and I wasn't sure if it was going to be available for others.

    the most development has to be and has been done in the firmware.

    Scheme attached !


    Attachments:
    FreeEMS_40_Board_Schema_v0.4.pdf [95.81 KiB]
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    Thu Sep 11, 2014 8:53 pm
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