AN1833 Freescale Semiconductor / Motorola, AN1833 Datasheet - Page 24

• Manufacturer Part Number: AN1833
• Description: A Low-Power Wireless Remote Control Transmitter and Receiver
• Manufacturer: Freescale Semiconductor / Motorola

Application Note
24
TRANSMITTER ENABLE
THE MCU GOES TO THE
INSTRUCTION FOLLOWING
STOP. THIS INSTRUCTION
SENDS THE MCU BACK TO
START.
ENTER A LOW-POWER
INITIALIZE KEYPAD
PORT BITS
TURN OFF
START
MODE
STOP
Figure 9. Transmitter MCU Flowchart (Sheet 1 of 2)
Freescale Semiconductor, Inc.
RELEASE OF THE KEY
For More Information On This Product,
(ACU NOT ZERO)
DEBOUNCE THE
KEYPAD INPUT
RETURN FROM
THE MCU “WAKES UP” WHEN A BUTTON ON THE KEYPAD IS PRESSED. THE EXTERNAL
INTERRUPT CAUSES THE PROCESSOR TO BEGIN CODE EXECUTION HERE.
Note: AN1239/D describes the connection of the Grayhill keypad to the MC68HC705J1A.
INTERRUPT
INTERRUPT
REQUEST
VALID
?
NO
Go to: www.freescale.com
YES
STORE KEYPAD INPUT
SET FIRST FLAG BIT
IN ADDRESS BYTE
KeyPad_Body
Note:
FIRST FLAG
BIT SET
?
KeyPad_Body is a subroutine that decodes a 4 x 4
keypad. Refer to AN1239/D.
NO
YES
STORE KEYPAD INPUT
IN COMMAND BYTE
Send_preamble
SEE SHEET 2
MOTOROLA
AN1833