AN1924 Motorola / Freescale Semiconductor, AN1924 Datasheet - Page 17

• Manufacturer Part Number: AN1924
• Description: AN1924 Interfacing Serial LCDs to a DSP56F805s SCI and Porting Code Using the Embedded SDK
• Manufacturer: Motorola / Freescale Semiconductor

A.3 Power Input
A.4 ADC Inputs
A.5 Relay Driver Outputs
A.6 Matrix KeyPad Input
A.7 Interfacing the LCD+
A.8 Keypad Interface
A.9 Keypad Options
The power input section consists of four through holes (Solder pads). The two holes marked GND are
grounds. The hole marked +5.5V to +15V is tied to the onboard regulator of the LCD+ module. The
hole marked +5V ties to the +5V bus and is used to bypass the LCD+’s onboard regulator when a
regulated +5V source is supplied.
The eight ADC inputs are labeled 1 – 8. By default, all ADC inputs are set to read voltage in the 0 to
+5V range.
There are nine Relay Driver connections (Labeled on the underside of the board as R1-8 and
RLY_VDC). The connections labeled R1-8 are the relay driver chip outputs; the RLY+VDC
connection provides access to the ULN2803A driver chip’s internal back EMF protection diodes.
The keypad input connections (visible in
connection. The lower eight of the 8x2 header connection (which are not visible in
used by the factory for programming and should be left unconnected.
The LCD+ can be controlled using any computer or microprocessor supporting 1200-57600 baud data
rates with an 8,N,1 data format (8 data bits, No parity, 1 stop bit).
The keypad interface supports matrix keypads up to 4x4 in size (16 keys). Instead of predefining the
keypad’s key serial data format as 0 through 15, each of the keypad’s keys is serially represented by a
user-definable byte value. This user-definable value, or “Tag”, is stored within the LCD+ EEPROM as
a 0-15 byte array. Each byte of the array corresponds to a key on the keypad (i.e., key 0 corresponds to
byte 0 of the array). When a key is pressed, the stored byte representation for that key number is sent
serially.
Various keypad options are supported by six user-definable options, or “modes”. These modes are set
by sending CTRL-X, followed by the user’s command byte containing the desired modes. As shown
in
Off
Mode Byte
Table
B0
B1
B2
A-2, placing a “1” in any one of the bits turns its corresponding option On, and a “0” turns it
“Key Beeps”
“Key Press Format”
“LCD Echo”
Name
Table A-2. LCD+ Keypad Options Table
Interfacing LCDs and Porting Code
Beep buzzer during each key press
Sends one byte for key down and one for key up
Echoes key press data, ASCII representation to LCD display
Figure
A-1) are the upper-most eight of the 8x2 header
Description
NetMedia’s Serial LCD+
Figure
A-1) are
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