Chapter 13, Dedicated led flasher, Introduction – Cirrus Logic EP73xx User Manual
Page 111: Led flasher register list, Programming example, Operational overview, Chapter 13. dedicated led flasher, Table 13-1: led flasher registers -1, Chapter 13 13 dedicated led flasher introduction, Led flasher register list programming example
EP7309/11/12 User’s Manual - DS508UM4
13-1
Copyright Cirrus Logic, Inc. 2003
1313
13
Chapter 13
13
Dedicated LED Flasher
Introduction
LED flasher provides a user interface to toggle a specific GPIO pin for use to flash an
LED or other signaling device. A benefit of this feature is that the system, regardless
of the processor state, will continue to control this port. Only a system reset, loss of
power, or malfunction would prevent normal operation of the LED flasher.
LED Flasher Register List
Programming Example
;*****************************************************************************
; Program PD0/LEDFLSH for 50% duty on a 1 sec interval
;*****************************************************************************
LEDFLSH
EQU
0x61
;
ldr
r0, =0x80002000
mov
r1, #LEDFLSH
str
r1, [r0,#0x2C0]
;
Operational Overview
The LED flasher feature enables an external GPIO (
PD0
/
LEDFLSH
) to be toggled at a
programmable rate and duty cycle with the intent of using this to toggle an LED. If
programmed,
PD0
will be dedicated to this task.
This module is driven from the RTC (32.768 kHz) oscillator and works in all running
modes because no CPU intervention is required.
The flash rate can be programmed from 1-4 seconds, and the duty cycle can vary from
1/15 to 15/16 with a 50% duty cycle at 8/16. The external pin can provide up to 4 ma
of drive current.
Table 13-1: LED Flasher Registers
Address
Name
Type
Size
Description
Page
0x8000.22C0
LEDFLSH
R/W
0
LED Flasher