Chapter 9: Configuration, Design Security, and Remote System Upgrades in the Cyclone III Device Family
Remote System Upgrade
9–81
Remote System Upgrade Registers
The remote system upgrade block contains a series of registers that stores the
configuration addresses, watchdog timer settings, and status information. These
registers are listed in
Table 9–26. Remote System Upgrade Registers
Register
Description
This register is accessible by the logic array and allows the update, status, and control registers to be
written and sampled by user logic. Write access is enabled in remote update mode for factory
configurations to allow writes to the update register. Write access is disabled for all application
configurations in remote update mode.
This register contains the current configuration address, the user watchdog timer settings, one option
bit for checking early
CONF_DONE,
and one option bit for selecting the internal oscillator as the startup
state machine clock. During a read operation in an application configuration, this register is read into the
shift register. When a reconfiguration cycle is started, the contents of the update register are written into
the control register.
This register contains data similar to that in the control register. However, it can only be updated by the
factory configuration by shifting data into the shift register and issuing an update operation. When a
reconfiguration cycle is triggered by the factory configuration, the control register is updated with the
contents of the update register. During a read in a factory configuration, this register is read into the shift
register.
This register is written to by the remote system upgrade circuitry on every reconfiguration to record the
cause of the reconfiguration. This information is used by the factory configuration to determine the
appropriate action following a reconfiguration. During a capture cycle, this register is read into the shift
register.
Shift register
Control register
Update register
Status register
The control and status registers of the remote system upgrade are clocked by the
10-MHz internal oscillator (the same oscillator that controls the user watchdog timer).
However, the shift and update registers of the remote system upgrade are clocked by
the maximum frequency of 40-MHz user clock input (RU_CLK). There is no minimum
frequency for
RU_CLK.
Remote System Upgrade Control Register
The remote system upgrade control register stores the application configuration
address, the user watchdog timer settings, and option bits for application
configuration. In remote update mode for the AS configuration scheme, the control
register address bits are set to all zeros (24'b0) at power up to load the AS factory
configuration. In remote update mode for the AP configuration scheme, the control
register address bits are set to 24'h010000 (24'b1 0000 0000 0000 0000) at power up to
load the AP default factory configuration. However, for the AP configuration scheme,
you can change the default factory configuration address to any desired address using
the
APFC_BOOT_ADDR
JTAG instruction. Additionally, a factory configuration in remote
update mode has write access to this register.
August 2012
Altera Corporation
Cyclone III Device Handbook
Volume 1
ALTERA [ ALTERA CORPORATION ]
