Matrix Orbital GLT240128 Legacy - Manual (Page 17)

2.5 Optional USB Header for USB modules only
The GLT240128 USB version has an optional four pin header for internal USB communications with
host units. This provides the same communication lines as the regular header, albeit in a different form factor
for greater customization. Again, please 78 see for power requirements.
Pin 1 GND
Pin 2 D+
Pin 3 D-
Pin 4 Vcc (see table 78 on page 62)
Figure 17: Optional Internal USB Header
2.6 Protocol Select Jumpers
The Protocol Select Jumpers, pictured below in Figure 18, provide the means necessary to toggle the
display module between RS-232 and TTL protocol levels. As a default for Non-USB modules, the jumpers
are set to RS-232 mode with zero ohm resistors on the 232 jumpers. In order to place the display module in
I
2 C mode you must first remove the zero ohm resistors from the 232 jumpers and then solder the resistors
on to the I 2 C jumpers, or bridge solder across the pads. The display will now be in I 2 C mode and have a
default slave address of 0x50 unless the I 2 C address has been changed. Similarly, in order to change the
display to TTL mode, simply remove the zero ohm resistors from the 232 or I 2 C jumpers and solder them
to the TTL jumpers. Although RS-232, USB, TTL and I 2 C are present, only 232/TTL/I 2 C are for use in the
Non-USB module. For the USB module operation the USB jumpers must be in place. There are three, one
is for power. If you wish to power it up from a non-USB source, you must remove one of the jumpers. The
jumper to remove is the rightmost USB jumper as seen if Figure 19.
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