Troubleshooting Communications Issues with the MegaSquirt and MegaSquirt-II

How do I reflash the firmware on my MegaSquirt-I?

Here are instructions for using Hypertrm.exe for updating the embedded software (all Windows installations have the HyperTerminal application.1) Remove the power from MegaSquirt.

2) Put a bootloader jumper pin (a bent piece of snipped off lead from a resistor, etc. will work fine – bend it into a U shape) across the two holes labeled “boot” on the V2.2 PCB or V3 PCB (short R6 for V1.01 PCBs),

3) Hook-up a serial cable (DB9 tune cable) from the computer to the MegaSquirt box and fire up HyperTerminal (Hypertrm.exe).  The easiest way to do this is to click Start > click run> type hypertrm > hit enter.  The application should launch, if HyperTerminal does not launch  – use a “find-file” function to search for “hypertrm.exe”

Note: you do not use TunerStudio to perform the firmware upload – this is done with the terminal program HyperTerminal (or similar, see below), and you should not have TunerStudio, or any other serial data application running on your PC (Best practice is to close all applications before starting step 3). At this point, leave the MegaSquirt unit un-powered.

4) You will see a HyperTerminal screen when you execute – type in any name you want in the box, and make sure the Red telephone with the little yellow telephone next to it is highlighted.

5) A new window appears. On the “Connect Using” selection, select the proper COM port that your serial cable is attached to.

6) Then another window with COM port settings pops up. Select 9600 baud, 8 data bits, no parity, 1 stop bit, and set flow control to “None”; – this is very important. HyperTerminal is now up.

7) Apply power to the MegaSquirt.  This can be done by giving it power from your car if its already installed in a vehicle or by plugging in a powered stimulator into the DB37 connection.  You should see the “Boot>” prompt appear in the terminal screen.

8) Type “H” and you will be shown the options available in bootloader mode. (This is not mandatory but is a good test to prove you are properly in the bootloader)

9) Hit “W” for “Wipe” – this erases the old firmware and settings.

10) Hit “U” for “Upgrade,” which will respond with the text “wait …”.

11) Then at the top of the HyperTerminal window click the “Transfer” dropdown menu, select “Send Text File…” (do not use the “Send file” mode – you are sending a text file).

12) Set “Files of type” to “All files” and select the .s19 file containing your assembled code (The .s19 is the last 3 characters of the file name and there should only be one file with this extension in any version of the firmware code you download) You will see no activity on the screen for about 40 seconds.

  • MS1/Extra firmware can be found here: MS/1Extra Manual  These files may need to be unzipped and the .s19 file is located inside
  • Standard B&G Megasquirt firmware can be downloaded here Download the Download the MegaSqurt megasquirt.s19 File Here.  (You will need to right click this link and click ‘save as’). You will need to select the path to save it to but the filename will be populated as megasquirt.s19.  You will not need to change the name.

13) Then the prompt will come back after 40 seconds or so, which means the operation is finished.  If you have the stimulator plugged in you can hit X in HyperTerminal and you should see the lights on the stimulator board start to work    

14) Turn off power to MegaSquirt and shut down HyperTerminal.

15) Remove the bootloader jumper from the 2 boot holes that you inserted earlier , and you are ready to go.

How do I connect to my MegaSquirt-I with MS1/Extra Firmware?

See our Software / Downloads Page.

Use the drop down box at the top right to set the CODE_VARIANT to MSNS-E.

  • Then open Windows Explorer (or My Computer) and browse to C:/Program Files/MegaSquirt/TunerStudio2.25/mtCfg/You’re looking for a file called  C:/Program Files/MegaSquirt/MegaTune2.25/mtCfg/MSnS-extra.ini.xxxWhere the .xxx represents the version of the MSnS-E firmware you are running. You MUST choose the right file here very important. For example if you’re running MSnS-E firmware version 024s9 OR 024s13 then you will find the file called (in this example the xxx will be 024) and use the RIGHT mouse button to drag and drop a copy of that file in the same folder (just drop it anywhere in the empty white space) and you’ll get a little menu. Choose COPY. Now you’ll see a file called Copy of’. You want to RIGHT click this file and you’ll get a menu, choose RENAME and enter the name MSnS-extra.ini’ without the quotes of course. Hit ENTER. Depending on how your PC is configured you may see the .ini part of the filename disappear after you hit enter, and it may just say MSnS-extra’. That’s OK as long as you know you had the .ini part of the filename in there. Don’t add it again.
  • Next, Open TunerStudio, Open the Communications’ menu from the top and select Settings’ Select the proper COM port (very important) and select 9600 as the Serial Data Rate’ (just as important).

That’s it– you should be able to connect to your MS-I with M1/Extra firmware now!

If you don’t know your COM port click START and RIGHT-click My Computer’ and select Manage’ from the little menu that pops up. Select Device Manager’ in the left pane of this window and then expand Ports (COM & LPT) in the right pane of this window. This shows your available COM ports, it has to be one of these. If you are using a USB adapter it’s usually pretty easy to tell which one it is as it will say something like ‘USB Adapter COM4’, if not then you may have to try each of them (usually there are only one or two unless you have a USB adapter).

How do I connect to my MegaSquirt-II ?

See our Software & Downloads Page

Then use the steps in the MSExtra MS2 Manual to configure TunerStudio for the MS-II and put the proper .ini file in place for the firmware you are running.  You MUST know the firmware version you are running.  If you bought an assembled unit from me this is written on the label on the underside of the ECU.  If you built it yourself you downloaded the firmware file and flashed it during assembly, you’ll need to know what version you used.  

There are a few steps to setting up TunerStudio, (follow them exactly) but then it should work just fine and connect right up. The only other thing you’ll need to know is what COM port you’re using, but you’ll have needed to know that in order to have reflashed the MS2’s firmware earlier…  NOTE— If you skip these steps from the confgure page linked above… you’ll soon be needing the next section of the documentation below because you’ll corrupt your firmware….  That’s not fun, not the end of the world, but not fun.

Here are the high level steps you want to make sure you do, these are described in detail in the MS2 Manuals  

  • Install TunerStudio 
  • Put the proper MegaSquirt-II.ini file in place.  (step 6)
  • Use the TunerStudio Configurator to set the CODE_VARIANT to “MS_II – Bowling and Grippo MegaSquirt-II” (step 7)
  • Configure TunerStudio for the proper COM port and the Serial Data Rate of 115200.  (Step 7 cont.)

That’s it, each of these steps are critical though, if you skip any one of them you’ll have a problem, if you complete each one you’ll connect right up!

Here’s the MS-II downloader application:

Then use the steps labeled ‘To use the downloader.exe:’ (1-11) to reflash your ecu, you’ll have to pop open the case to do so. It’s easier to do this on stimulator, but you can do it with it getting power from your car without a problem as well. Just power it up whenever it tells you to plug the stimulator in.