Matrix Orbital GLK12232-25-SM - Manual (Page 20)

is high. Next, the display must be addressed using a one byte hexadecimal value, the default to write to the
unit is 0x50, while read is 0x51. Then information can be sent to the unit; even when reading, a command
must first be sent to let the unit know what type of information it is required to return. After each bit is sent,
the display will issue an ACK or NACK as described above. Finally, when communication is complete, the
transaction is ended by toggling the data line from low to high while the clock line is high. An example of
the use of this algorithm to write a simple “HELLO” message can be seen in 3.
Table 3: I 2 C Transaction Algorithm
START Toggle SDA high to low
Address 0x50
Information 0x48 0x45 0x4C 0x4C 0x4F
STOP Toggle SDA low to high
4.1.3 Serial Communication
In addition to being able to communicate via I 2 C the GLK12232-25-SM communicates natively through
the RS-232 protocol at at a default baud rate of 19,200 bps and is capable of standard baud rates from 9600
to 115,200 bps. Furthermore the GLK12232-25-SM is also capable of reproducing any non-standard baud
rate in between using values entered into our baud rate generation algorithm and set through command 164
(0xA4). The display module communicates at standard voltage levels of -30V to +30V or at TTL levels of 0
to +5V by setting the Protocol Select Jumpers to TTL.
4.2 Turn Flow Control On
Syntax Hexadecimal 0xFE 0x3A [full] [empty]
Decimal 254 58 [full] [empty]
ASCII 254 “:” [full] [empty]
Parameters Parameter Length Description
full 1 Bytes remaining before issuing a
almost full message. (Full is 0)
empty 1 Bytes available before issuing a
almost empty message. (Empty is
128)
Matrix Orbital GLK12232-25-SM 15