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Screen package format:
The z20 command encodes a complete display update into a single, fixed length packet. The data
encoded
and needs decoding before use. As sent over the wire the packet format is:
z20,payload
After decoding the payload format is:
Offset
0
24
48
49
The LCD display data is binary, with 0..7 representing soft characters, the remainder being mainly standard ASCII
display codes (up to 127). There are some differences between the LCD character set and that of a standard
Windows machine. In particular:
LCD Code
0
1
2
3..7
0xDF
0xE1
0xEE
128..255
The cursor is encoded as follows:
Bit
7
6
5..0
If neither bits 6 or 7 are set then no cursor should be shown.
The soft character cache consists of a series of 5 bytes, each of which represents an index into the soft character
map table. If a particular cache location is not in use then it will be set to 0xFF. The cache index is such that LCD
char 3 maps to cache index 0 (i.e. subtract 3 from the LCD code to obtain the index into the cache). The cache is
sent with each display update as the soft characters mapped into cache can change on each display update.
4618 - 021
where payload = 72 bytes of base64 data.
Size (bytes)
Content
24
First line of LCD display
24
Second line of LCD display
1
Cursor type & position
5
Soft character cache (5 entries)
Character
Windows character code
not used
>
or 0x25BA
<
or 0x25C4
Soft character cache (0..5)
°
0x00B0
ä
0x00E4
ñ
0x00F1
Content
Underline cursor
Block/blinking cursor
Cursor position, 0..23 is the first row, 24..47 is the second row.
Japanese / other special characters.
APPENDIX D
is base64
139
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