130-28029 Parallax Inc, 130-28029 Datasheet - Page 306

• Manufacturer Part Number: 130-28029
• Description: KIT PARTS SMART SENSORS
• Manufacturer: Parallax Inc

Specifications of 130-28029

• Accessory Type: Education Kit
• Product: Microcontroller Accessories
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• For Use With/related Products: BASIC Stamp®
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Contains lead / RoHS non-compliant

Page 294 · Smart Sensors and Applications
SUMMARY
Both distance and tilt measurements lend themselves to bar graph displays. Most bar
graphs can be done using only one or two of the Parallax Serial LCD's eight custom
character memory slots. The custom character definitions for bar graphs can either be
stored in the BASIC Stamp EEPROM, or defined by code that relates the value being
graphed to the number of pixel lines or columns that need to be displayed.
Storing custom characters in EEPROM involves
each. The lower five bits of each byte store the bit pattern for each of the eight (five-
pixel-wide) lines that make up a character.
make it possible to copy the starting address of the bytes in a given
variable.
operations that sequentially copy bytes to a variable, then send the contents of that
variable to the LCD.
Displaying bar graphs is typically more memory-efficient if the characters can be
generated based on the value. When the bar graph is horizontal, a
useful for storing binary values that correspond to the number of columns that will have
black pixels in a given custom character. For vertical graphs, bits can be shifted into a
variable. In either case, subroutines can examine the bits in a variable, then darken pixels
in a certain number of rows or columns in a character.
Questions
1. What part of
2. How do programs in this chapter tell the
3. How does HorizBarGraph.bs2 store information about which columns in a
4. Why can you use just one byte instead of eight to define a custom character with
5. What does the instruction
character definition?
character to define and where to find the character definition? How do you
specify a character location for the
display two different custom characters at the same time, can you use the same
custom character definition? Why?
custom character should have black or white pixels?
certain columns black?
TestVerticalBars.bs2?
A subroutine can use the variable that stores the start address for
DATA
directives makes it possible to find the starting address of a
IF rowMap.LOWBIT(index) = 1 THEN
Disp_Cust_Char
Symbol
DATA
Def_Cust_Char
names preceding
directives that contain eight bytes
subroutine? If you want to
DATA
LOOKUP
subroutine which
DATA
directive into a
command is
directives
... do in
READ