Loader (TinyBooter) G120 and EMX Families

This document is obsolete.

Last modified August 22, 2014


Cross Reference: If you have not already, you might want to read the introductory page  explaining the firmware (TinyCLR) and the loader (TinyBooter). It gives a basic procedure for determining whether or not you need to update. It also contains tips and trouble shooting advice.


This document describes updating TinyBooter for specific processors.

To make sure that this document is for your processor see the generic Loader (TinyBooter) documentation.


There are three ways to update the processors supported by this page:

  1. Easiest: we recommend using  FEZ Config. Described below.
  2. A manual process. Described below.
  3. Legacy firmware/loader updaters (deprecated, unsupported). A link to the legacy updaters is found on the main support page. Use the one named for your processor and follow the online instructions.


Automated Method of Update. Using FEZ Config

Using FEZ Config

You can only use FEZ Config if its version number is greater than 0.1.3 (013). Otherwise, you must use the Manual Procedure Below

For all System on Modules, use the Manual Procedure Below

  1. Attach your device to your computer,
  2. launch/run FEZ Config,
  3. click on Advanced menu,
  4. click on Loader (Tiny Booter) Update,
  5. locate your device in the sub-menu

If your device/processor is not listed, you are on the wrong web page. Go to the general Loader page, and follow the links for your device.

  1. click your device selection; and
  2. follow the directions presented.


Manually Updating

Using a Manual Update Procedure

The processor update steps for the following devices are identical, with two exceptions: (1) which is the way the device is put in loader mode. This is done via switches, jumpers, or buttons; and (2) selecting the file on your development system that contains the Loader (TinyBooter).

TinyBooter Update

  1. First, install the latest GHI NETMF SDK (which includes the latest TinyBooter binary files). 
  2. Install TeraTerm software. Download TeraTerm.
  3. Disconnect the device from the PC.
  4. Open TeraTerm.Select serial and click the arrow to drop down the list of Update Preparation: Loader (TinyBooter) and Firmware (TinyCLR). Note how many COM ports you have and write them down. For example you may only have COM3:

If you do not see any COM ports in the list and you can not get anything to happen in the serial area then skip to step 5 below

  1. Close TeraTerm
  2. Connect the device back to the development system
  3. The next step, putting the device in Loader mode, varies by device. Find yours below, and configure it.



For FEZ Spider put the board switches in Loader configuration and press reset (while board is powered up) or power cycle the device.



For FEZ Spider II put the board switches in Loader configuration and press reset (while board is powered up) or power cycle the device.


G120 has a few Special Pins for accessing the installation mode. The pins have internal pull-ups so leave them unconnected for 'High' or connect to 'GND' for 'Low'.

LDR0 (P2.10) LDR1 (P0.22) Boot Access
X High Firmware (TinyCLR)
High Low Loader (Tinybooter)
Low Low GHI Bootloader


For G120 connect LDR0 and LDR1 to GND (that's P2.10 and P0.22) and reset (while device is powered) or power cycle the device.


Pin 59 P1_30 AD4/COM4 OE must NOT be grounded on power-up for GHI Bootloader to function correctly.


Similar to the G120, pins are connected to ground to make them LOW:

Pin 7 (P2.5) Pin 3 (P0.4) Pin 53 (P2.11) Boot Access
Low Low Low Loader
Low Low High TinyBooter


EMX:  Ground pins 7, 3, and 53 then reset (while device is powered) or power cycle the device.

Reference: see the EMX Manual



For FEZ Cobra II press and while holding LDR0 and LDR1 buttons, press the reset button (while board is powered)  or power cycle the device.

Windows may install a new driver file: GHI_BootLoader_Interface.inf

  1. Without powering down or resetting the device, return it to its default state by releasing buttons, ungrounding pins, or moving switches.

GHI Boot loader commands are case sensitive. Be sure you type the command letters in the same case as shown in this document.

  1. If windows is installing a new driver, wait until it finishes.
  2. Open TeraTerm and observe what COM ports are now available. You should have a new COM port. 
  3. Select the new COM port and click “OK”.
  4. In the Setup menu, under serial port setup: Baud: 115200, parity: none, stop: 1 bit, flow control: none.
  5. Now press the “b” button on the keyboard. TeraTerm will reply with BL for every time you press “b”. Now press “V” (upper case) to get back the loader version number. Note, your version number might be different! This version is NOT related to GHI NETMF SDK or loader.
  1. Erase the flash memory using E command then press Y to confirm (this will take several seconds)

Installing the new loader is simple but it requires a terminal program that supports XMODEM file transfer (which TeraTerm does). XMODEM has a few settings, GHI boot loader requires 1K transfers with 16Bit CRC error checking.

XMODEM transfer is initiated using the X command. After the X command is entered, the device will start sending back the “C” character to TeraTerm. This “C” is an indicator telling you the device is waiting for data.

Entering X command...

Once you see the “C” character appearing on the terminal window, you can perform the XMODEM transfer from the menu  File > Transfer > XMODEM > Send... 

A dialog box will appear. You will need to navigate to the proper folder (via Look in:). The directory and file names are dependent on your device and SDK release:

For all the directory names below, your version number may vary. For example you may have v4.2 in place of vX.X

For NETMF 4.3 based SDKs (GHI's "NETMF and Gadgeteer Package 2014 R2" and newer SDKs) a subdirectory heirarchy is used ...\Firmwares\EMX or ..\Firmwares\G120; in this case, the TinyBooter file is named loader.ghi

For NETMF 4.2 based SDKs (GHI's "NETMF and Gadgeteer Package 2014 R1" and previous):

  1. EMX, Spider: directory: C:\Program Files (x86)\GHI Electronics\GHI Premium NETMF vX.X SDK\EMX\Firmware\TinyBooter, file: TinyBooter.GHI
  2. G120, Cobra II, Spider II: directory: C:\Program Files (x86)\GHI Electronics\GHI Premium NETMF vX.X SDK\G120\Firmware\TinyBooter, file: G120_TinyBooter.GHI

Legacy directory (4.1 SDK) for EMX:

C:\Program Files (x86)\GHI Electronics\GHI NETMF v4.1 SDK\EMX\Firmware\TinyBooter

Before clicking on "Open" make sure the 1K button is selected (see above). Then click "Open." Updating the loader takes a few seconds. Once installation has finished and the file is valid, the new loader is executed automatically and you will not see “BL” again. If you do see the "BL" again after this process, it means that the update process failed. You might need to double check that the downloaded file is not corrupted.

At this point you have a clean Flash memory with only the loader (TinyBooter). Proceed to firmware (TinyCLR) installation instructions or return to the page that directed you here (back button in the browser).

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