27220 Parallax Inc, 27220 Datasheet - Page 187

• Manufacturer Part Number: 27220
• Description: BOOK STAMPWORKS
• Manufacturer: Parallax Inc

Specifications of 27220

• Accessory Type: Booklet
• Product: Microcontroller Accessories
• Lead Free Status / RoHS Status: Not applicable / Not applicable
• For Use With/related Products: StampWorks
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Not applicable / Not applicable

symbol, etc). The MC14489 can also be configured to control up to 25 discrete LEDs
(using No Decode mode).
The MC14489 connects to the LED displays in a straightforward way; pins A through
H connect to segments A through G and the decimal point of all of the common-
cathode displays. Pins BANK 1 through BANK 5 connect to the individual cathodes of
each of the displays (Digit 0 – Digit 4). If you use fewer than five digits, omit the
highest digit number(s). For example, this experiment uses four digits, numbered 0
through 3, so Digit 4 need not be connected.
When the MC14449 is used with seven-segment displays, it can be configured to
automatically convert binary-coded decimal (BCD) values into appropriate patterns of
segments – this is called Hex Decode mode. This makes the display of decimal and
hexadecimal numbers quite simple. The MC14489 also has a Special Decode mode
that displays a few letters and symbols. Finally, there is a No Decode mode wherein
the bits used for a digit register are output directly (but only to segments A-D;
segments E-G are turned off in No Decode mode).
The key to getting information into a display controlled by the MC14489 is
understanding the configuration register and how the bits interact to control the
display decoding. The table below is a review of the configuration register bits and
how they affect the display:
Sending data to the MC14489 happens one of two ways: 1) the eight bit
configuration register is sent, or 2) 24 bits (six nibbles) that hold display information
are transmitted. There are no addresses for the data as with other synchronous
serial devices; the MC14489 properly routes information sent to it based on the size
of the packet.
Bit0
Bit1
Bit2
Bit3
Bit4
Bit5
Bit6
Bit7
0 = display blank; 1 = display on
0 = Hex Decode for Bank 1; 1 = Depends on Bit6
0 = Hex Decode for Bank 2; 1 = Depends on Bit6
0 = Hex Decode for Bank 3; 1 = Depends on Bit6
0 = Hex Decode for Bank 4; 1 = Depends on Bit7
0 = Hex Decode for Bank 5; 1 = Depends on Bit7
0 = No Decode; 1 = Special Decode for Bank1 – Bank 3
0 = No Decode; 1 = Special Decode for Bank4 – Bank 5