atf1508be ATMEL Corporation, atf1508be Datasheet - Page 12

• Manufacturer Part Number: atf1508be
• Description: High- Performance Cpld
• Manufacturer: ATMEL Corporation

5.3
5.4
12
Direct Reconfiguration Access – DRA
ISP Programming Protection
ATF1508BE
Figure 5-2.
This reconfiguration mode allows the user to directly modify the internal static registers of the
CPLD without affecting the configuration data stored in the embedded memory. It is more useful
in cases where immediate and temporary context change in the function of the hardware is
desired.
The embedded configuration memory in the ATF1508BE does not change when a new set of
configuration data is passed to the ATF1508BE using the DRA mode. Instead, the internal static
registers of the CPLD are directly written with the data entering the device via the JTAG port. In
other words, it's a temporary change in the function performed by the CPLD since a power
sequence results in the device being configured again by the data stored in the embedded
memory.
The ATF1508BE has a special feature that locks the device and prevents the inputs and I/O
from driving if the programming process is interrupted for any reason. The I/O pins default to
high-Z state during such a condition.
All ATF1508BE devices are initially shipped in the erased state, thereby making them ready to
use for ISP.
CPLD Device
ATF1508BE
Configuration of ATF1508BE Device Using a Processor and Memory
TDO
TMS
TCK
TDI
Serial Data
Data
Processor
Memory
Address
3663A–PLD–1/08