Matrix-orbital LCD/VFD Legacy Manual do Utilizador descarregar pdf (Página 24)

Table 12: Hex Value Table

Binary Hex Decimal Binary Hex Decimal

0000 0 0 1000 8 8

0001 1 1 1001 9 9

0010 2 2 1010 A 10

0011 3 3 1011 B 11

0100 4 4 1100 C 12

0101 5 5 1101 D 13

0110 6 6 1110 E 14

0111 7 7 1111 F 15

Based on the table, the byte 01001011 can be represented in hex as 4B, which is usually written as any

of 4Bh, 4BH, 4B hex or 0x4B.

The numbers can also be expressed in decimal form if preferred.

6.3.1 ASCII Characters

Since computers deal internally with numbers only, but externally with both letters and numbers, several

schemes were developed to ’map’ written characters to numeric values. One such scheme has become

universal, the American Standard Code for Information Interchange, or ASCII. ASCII tables are readily

available from a number of sources. A few examples will do here;

Table 13: Example of an ASCII Table

The letter A has a value of 65 decimal or 41 hex

The letter a has a value of 97 decimal or 61 hex

The number 0 has a value of 48 decimal or 30 hex

The number 9 has a value of 57 decimal or 39 hex

This gives rise to the possibility of confusion when parameters are being set on the display. For example,

the GPO ON and OFF commands use a number to indicate which GPO is being controlled. We’re told that

acceptable values are 0 to 6. All such parameters must use numeric values (i.e., the actual byte values). If

we send the ASCII number 0 by mistake it will actually give the value 48 decimal (30 hex) to the parameter,

which is wrong.

In the tables given in the following sections ASCII characters are shown as ’A’, with single quotes.

6.4 Text Commands

Syntax in the tables below is given in hex, decimal and decimal with ASCII, in that order, one per line.

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