Extruder Controller v2.2

Updating the ECv2.2 bootloader

If we shipped your extruder controller before July 15th, 2010, you probably have the stock Arduino bootloader installed rather than the custom EC22 bootloader. Although unlikely, the stock Arduino bootloader can lead to problems with your board's power MOSFETs. If you have or can borrow an ISP programmer, you can install an alternate bootloader that will solve this issue.

What's a bootloader?

It's a small bit of code that's installed on every board that allows a user to upgrade the firmware without needing special equipment (like an ISP programmer). This is the reason why the boards usually take a few seconds to begin responding after they're turned on; the bootloader is waiting to see if the user wants to install new firmware before running the existing firmware.

What's a MOSFET?

The MOSFETs on the extruder board are the little transistors that switch the heaters, valves, and other power electronics off and on.

What's the problem?

The problem is that while the bootloader is running, the signal from the microcontroller to the MOSFET is what's known as "floating": it's neither high nor low, and can drift to any value. When the MOSFET is halfway turned on, it can dissipate a lot of power, which means it can cause the MOSFET to heat up. The good news is that since the bootloader only runs for a couple of seconds, it's unlikely that this will damage your MOSFET.

Do I need to install the new bootloader?

Not necessarily. If you haven't had any trouble with your MOSFETs yet, you're unlikely to experience a problem in the future. If you have access to an ISP programmer, we recommend following the instructions below, just to be on the safe side. If you don't, don't sweat it! Your extruder controller's MOSFETs will almost certainly continue to operate as expected.

If your extruder controller shipped from Makerbot on or after July 15th, 2010, you already have the updated bootloader installed. If you built your own board, you'll want to install this bootloader. If your board came from another vendor, please contact them to find out what bootloader is installed on your board.

Installing the EC22 bootloader using the Arduino 0018 software

Step 1: download and install Arduino 0018

You can download the Arduino software from Arduino's download site. We've tested this procedure with Arduino 0018, although it will most likely work well with subsequent versions as well.

When you install Arduino 0018, keep track of what directory you install it in; you'll need this for the next step.

Step 2: download and install the EC22 bootloader

You can download the new bootloader from our Google Code site. Unzip the archive somewhere convenient. Inside, you'll see a "hardware" directory. Copy this directory into the Arduino directory. This should add a couple of files to your Arduino installation, and overwrite a couple more.

To check that you've installed the EC22 bootloader package correctly, start the Arduino software. If you see an "Extruder Controller v2.2" entry in your Tools>Board menu, you're good to go!

Step 3: disconnect your A, B, and C terminals

Uploading new firmware can turn your MOSFETs on and off during the upload process, so unscrew and disconnect any wires that you have plugged into your A+, A-, B+, B-, C+, or C- terminals. (Keep track of which went where, so you can plug everything back in again when you're done!)

Step 4: connect your ISP programmer

Connect your ISP programmer's 6-pin connector to the shrouded 6-pin header on the board. Do not use the 10-pin connector! The 10-pin header on the board is for peripherals. You will not be able to program the bootloader through the 10-pin connector.

Attach the ISP programmer to your computer as you ordinarily would.

Step 5: start Arduino and program the booloader

Start the Arduino software. From the Tools>Board menu, select "Extruder Controller v2.2". Then, from the Tools>Burn Bootloader menu, select your ISP programmer. The Arduino software will begin to upload the firmware. Ordinarily, this will take two to three minutes to complete, so be patient.

When you're done, you'll see the "debug" LED on the board flash periodically.

Step 6: install your firmware

Now that you've got your bootloader updated, you can install your firmware as you ordinarily would. If you're using ReplicatorG, follow the directions here.

That's it! You should be up and running with the new bootloader.

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