Power Supply:
Complete steps 1-23, soldering the components to the board.
***Be sure to observe the correct orentation of all diodes and capacitors. Unless you are blind or stupid, there really isn't a way to screw up as long as you pay attention. The proper direction is cleary explained in each step that involves requires soldering one to the board, and the silkscreen on the board shows the "+" for capacitors, and "stripe" for diodes.***
Board with connectors installed and CPU socket installed (steps 1-3):
Proper mounting of Voltage Regulator. (U5, step 21) This is also how all components mounted to the heat sink should look.
DON'T FORGET THE HEATSINK COMPOUND! Be easy when bending the leads, dont over stress them, they could break (think of a bending paper clips). Use a nylon screw for mounting this one, and trim the excess of the screw off the bottom after mounting.:
This is the board after the power circuit is completed. Also notice I have already installed all of my
IC sockets, now is a good time to go ahead and solder them in:
*After completion, hook up your MegaStim, and test that you have power across the specified pins at the CPU socket. (see assembly guide for pin locations). the chart is below step 23.
*Its also a good idea to check that you have 8-9 volts at your voltage regulator (U5) on the pin closest to the DB9 connector, a good, solid ground at the center pin-to-heatsink (less than 1 ohm resistance), and 5 volts at the pin closest to the DB39 connector.
If everything passes the test, your good to go ahead to the next section.
If not,
STOP, go back and check everything before proceeding! Make sure that all components are installed (its easy to miss one sometimes), make sure capacitors and diodes are in the right orientations, you have good solid soldered joints, and if you opted to use a 9v battery to power the MegaStim, be sure you have a fresh, new battery (most common problem).
Serial Communications Construction & Testing
Complete steps 24 and 25.
***Be sure to observe the correct orientation of all diodes and capacitors. Unless you are blind or stupid, there really isn't a way to screw up as long as you pay attention. The proper direction is clearly explained in each step that involves requires soldering one to the board, and the silkscreen on the board shows the "+" for capacitors, and "stripe" for diodes.***
With this, you have enough to test your megasquirt's communications.
You MUST verify that you have a true “pass-thru” db-9 cable. This means that pin 1 goes to pin 1 on the opposite connector, pin 2 goes to pins 2 on the opposite connector, etc. You can test this easily with an ohmmeter.
To test the communications part of the megasquirt, you need HyperTerminal. If you are using an older computer/laptop to tune and test your megasquirt, then most likely it is already on the computer.
To check, go to start menu -> programs -> accessory’s -> communications. You should find it under this.
If you don’t have it, you can download it for free by clicking on the link provided in the assembly section of Megamanual.
Once you have HyperTerm, Take your db-9 cable and using alligator clips or a small piece of wire, connect pins 2 & 3. By jumpering these two, we are providing (in shortest terms) a "u-turn" for information coming out of the computer. This step ensures that we have HyperTerm properly setup on our computer so that we accurately and reliably test communications on megasquirt. All information sent through the output pin will be "u-turned" back into the input pin.
Plug the cable into your computer/laptop, but not your megasquirt. IMPORTANT! Do not let the alligator clips or wire touch the metal casing around the plug or you will not get the proper results!
Start HyperTerm by clicking on the icon. Start a new connection by typing in a name, such as megasquirt. Click OK.
Next, a “connect to” box will appear. Under “connect using”, select your COM port. Most will use COM1, so try this first. Select OK.
You will then have a “port settings” box pop up. Set all parameters to those shown below. (Megasquirt 1)
With that done, you should be able to hit any key on the keypad and have that digit show up in the dialog box. If not, double check all settings, COM port, and proper pins selection on the cable.
Now that we have HyperTerm tested, we can now test the communication on the megasquirt. Remove the ”jumper” from the end of the cable and plug it into the MS.
We no want to Jumper pins 12 & 13 on the 40-pin processor socket. This is going off teh same concept described earlier when we "looped" the DB-9 cable. This is providing a "u-turn" for information so we can determine that our megasquirt will respond to our laptops when we tune.
The pins are right beside the “R44” resistor/location.
Plug in you stimulator (told ya you needed one) and power it up. You should now be able to type any letter/number into HyperTerm and it should show up on the screen.
Clock Circuit assembly and testing
Complete steps 27-37.
***Be sure to observe the correct orientation of all diodes and capacitors. Unless you are blind or stupid, there really isn't a way to screw up as long as you pay attention. The proper direction is clearly explained in each step that involves requires soldering one to the board, and the silkscreen on the board shows the "+" for capacitors, and "stripe" for diodes.***
Complete step 38. NOTE: Use
CAUTION when handling the crystal. It is
VERY fragile and can be destroyed easily. Once soldered in place, bend down slightly into a small dab of RTV silicone. This will help dampen shock and vibrations, insuring trouble-free operation.
Complete step 39. NOTE: Use
CAUTION when installing the processor. The “legs” are thin and fragile. Be sure ALL “legs” are in the socket before firmly pressing it down into place or damage can occur. Some straightening of the legs will be necessary and is normal. They bend very easily, just be sure to use care when doing so…don’t over bend or they can break!
We are now ready to test.
You must download and install Megatune at this time in order to test the clock circuit. You can find the link under the clock circuit assembly section in Megamanual.
Once you install Megatune, click on the icon to start testing. For now, when “Select Project” box appears, click
“MS1 Original BG Code”.
When MegaTune appears, click “File”, and “Configuator”.
Click the “plus sign” to pull down the menu. Select “code_variant”.
Ensure in the upper box that “MS_1 – Bowling and Grippo Megasquirt”
Once all this is complete, go to “file” and select “run Megatune”.
Plug in the DB-9 cable from your PC/Laptop to your Megasquirt, and then connect your stimulator. With Megatune, Under “tuning” select “real-time display”.
You should see the time counting up every second. If this is up and running, you are good to move to the next step.
If not,
STOP, go back and check cable connections and that you have a good battery (if running 9v on the stimulator, the most common problem). These last only a few minutes during testing. If all that looks, good, go back and check all solder joints and connections (and hope you handled the “crystal” carefully like I told you earlier!)