Hardware Configuration Control; Table 5-1. Hardware Configuration Control Latched Pins - Cirrus Logic EP93 Series User Manual

System Controller
EP93xx User's Guide
certain system variables such as RTC, SDRAM refresh control/global configuration, and
the Syscon registers.
5
Note: If PLLs are enabled, user reset does NOT disable or reset the PLLs. They retain their
• Three-key reset. When F2, F4, and F7 are pressed, a user reset occurs.
• Software reset and watchdog reset. They perform the functions of the user reset, but are
under software control.
"Watchdog" on page 19-3
regarding which reset event occurred. Note that only the Watchdog timer contains
information about a user-generated 3-key reset.

5.1.3 Hardware Configuration Control

The Hardware Configuration controls provide a mechanism to place the system into various
boot configurations. In addition, one of several external boot memory options can be selected
at system wake up.
The Hardware Configuration controls are defined by a set of device pins that are latched into
configuration control bits on the rising edge of the PRSTn or RSTOn pin. The different
hardware configuration bits define watchdog behavior, boot mode (internal or external), boot
synchronicity, and external boot width. The latched pins are described in
The latched version of these signals have an "L" prefix, are stored in the SysCfg register, and
are readable by software. Note that the signals EECLK and EEDAT may have 1 kΩ pull-up
resisters if used in an open-drain two-wire serial port application. (The default state
assignments will assume these pull-ups.)
The Hardware Control configurations are show in
5-2
frequency settings.
and "PwrSts" on page 5-14

Table 5-1. Hardware Configuration Control Latched Pins

Pin Name(s)
CSn[1]
CSn[2]
CSn[3]
EECLK
EEDAT
BOOT[1:0]
ASDO
CSn[7:6]
Copyright 2007 Cirrus Logic
registers contain the information
Action
Enable/Disable Watchdog
reset timer
Enable/Disable Watchdog
reset duration
Should be pulled-up to "1"
Select internal or external
boot
Should be pulled-up to "1"
Select boot mode
Select synchronous or
asynchronous boot
Select external boot width
Table 5-2.
Table 5-1.
DS785UM1