DM300014 Microchip Technology, DM300014 Datasheet - Page 60

• Manufacturer Part Number: DM300014
• Description: BOARD DEMO DSPICDEM 1.1 GEN PURP
• Manufacturer: Microchip Technology

Specifications of DM300014

• Processor To Be Evaluated: PIC30F
• Data Bus Width: 16 bit
• Interface Type: RS-485, CAN, SPI
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

dsPICDEM™ 1.1 Development Board User’s Guide
B.3
DS70099B-page 56
COMMANDS
B.3.1
All commands recognized by the LCD controller are one to three bytes in length.
The command structure is designed to follow a simple rule that allows the interface to
be self-synchronizing at the command level (i.e., if a command is corrupted for some
reason, the controller can resynchronize on the command stream without special error
recovery procedures). The rule is that the first byte of a command always has its
MSB = 1 and the remaining bytes of the command have their MSB = 0. There is an
exception to the rule that MSB = 0 for all bytes except the first byte. Some of the column
commands can have data in the MSB of their second byte and thus, may violate this
rule. The processing code in the LCD controller will parse these special commands and
allow the command exception.
All commands follow the form of a leading identification byte followed by zero to three
data bytes. The data bytes are not condensed or combined with other data, or modified
from the native form of the data. There is no handshaking or flow control required
because of the speed and buffer depth of the controller. This greatly simplifies the
interface on the dsPIC side since there is little advantage to putting wrappers around
the individual commands. Nothing needs to be done to the data other than to send it.
B.3.2
The LCD has three data types, each based on its own independent coordinate
systems. The data types are:
• Character
• Pixel
• Column
Associated with each coordinate system is a “current” position of which each is
independent of the other. These positions are:
• CharPos
• PixPos
• ColPos
B.3.2.1
The character commands are used to write characters to the display. The character
coordinates are based on a 5 x 7 dot font justified to the upper left corner of the 6 x 8
box. The character cursor is a 5-pixel wide horizontal line that is justified to the lower
left corner of the 6 x 8 box and can be turned on or off, or can be set to blink.
Character operators are based on character coordinates R and C (i.e., Row and
Column). The current position, CharPos, specifies both the location of the character
cursor and the default position that the next character command will use. The home
position is the top left of the LCD display, ChrPos = (0,0).
The LCD accommodates four character rows (0-3) and 20 character columns (0-19).
Unless otherwise specified, incrementing ChrPosC beyond column 19 will wrap to the
next row (i.e., ChrPosC = 0 and ChrPosR + 1). If ChrPosR exceeds 3, it will wrap to
row 0.
Command Structure
Command Types
CHARACTERS
Advance Information
 2003 Microchip Technology Inc.