Device
sys_clkreq
sys_32k
sys_xtalin
sys_xtalout
sys_clkout1
sys_clkout2
sys_nrespwron
sys_nreswarm
VIO
Reset
push-button
OR
sys_altclk
sys_boot[6:0]
init-004
Public Version
www.ti.com
Preinitialization
26.2.2 Clock and Reset
26.2.2.1 Clock and Reset Overview
shows the clock and reset environment that gathers the clocks and reset signals related at the
system level, as well as system expansion signals.
Figure 26-3. Clock and Reset Environment
The main features of the system interface are:
•
A clock request output to an external square clock source
•
12, 13, 16.8, 19.2, 26, or 38.4-MHz reference clock input from the external crystal oscillator (only 12,
13, 16.8, or 19.2 MHz) or the digital clock input (all frequencies)
•
32-kHz CMOS clock input
•
An additional clock input up to 54 MHz
•
Two configurable output clocks
•
Seven input signals to define the boot mode
•
Two reset sources
–
POR (cold reset)
–
Bidirectional warm reset
3513
SWPU177N – December 2009 – Revised November 2010
Initialization
Copyright © 2009–2010, Texas Instruments Incorporated
