Bootloader

The GHI Electronics Bootloader is the first program that runs on a SITCore device after reset. It initializes the chip, then either hands off to TinyCLR (the default) or stays in bootloader mode for firmware updates — selected by the LDR pin.

note

The bootloader is hardcoded into the device. It can't be changed and never needs to be updated.

The bootloader communicates over USB (as a virtual serial port) or a regular UART serial port. The MOD pin selects which interface is used — see Special Pins for details.

Updating firmware

For the standard firmware update procedure using TinyCLR Config, see Getting Started → Install or update firmware.

The manual procedure on this page is a backup — use it when TinyCLR Config can't be used (for example, on a non-Windows host or during automated production deployment).

Manual update via XMODEM

1. Put the board in bootloader mode — hold the LDR signal low while resetting the board. See each board's pinout for the LDR pin location.
2. Open a terminal application — Tera Term is a good choice on Windows.
3. Select serial mode and pick the COM port associated with your board. (If unsure, check Device Manager.)
4. Press V then Enter. The bootloader returns its version number (v2.x.x).
5. Press U or X then Enter:
   • X for a .ghi firmware file
   • U for a .glb firmware file
6. Press Y then Enter to confirm. You'll see CCCC... indicating the bootloader is waiting for the firmware.
7. In Tera Term, go to File → Transfer → XMODEM → Send.
8. Important: check the 1K option in the XMODEM dialog.
9. Select the firmware file and start the transfer.
10. When the transfer completes, reset the board.

Bootloader commands

All commands and results are terminated with CR + LF (\r\n). OK. is sent after each successful command.

On startup, the bootloader sends a banner terminated by OK. Once you receive the banner, send any of the case-insensitive single-character commands below.

Commands that modify the device require confirmation — send Y or y followed by a newline to proceed; anything else cancels.

Command	Description
V	Returns the current bootloader version
N	Returns the current device type
E	Erases all user sectors of the device
R	Runs the firmware if present
B	Increases the baud rate in serial mode to 921,600
X	Upload a .ghi firmware file via 1K XMODEM. Only send .ghi files meant for this device.
U	Upload a .glb firmware file

USB drivers

note

USB drivers are only needed for Windows 7 and 8. Windows 10 and 11 use built-in drivers — no install required.

File	Date	Status	MD5
v1.0.0 x64	2018-12-27	Production	74D66FC4236126A83CCCFE28D556F339
v1.0.0 x86	2018-12-27	Production	8BDE68132452E22B14597C0972ABA8FD