ATF1504BE Datasheet, PDF (12/30 Pages) ATMEL Corporation – Highperformance CPLD

Figure 5-2. Configuration of ATF1504BE Device Using a Processor and Memory
ATF1504BE
CPLD Device
TCK
TDO
TMS
TDI
Serial Data
Processor
Data
Address
Memory
5.3 Direct Reconfiguration Access – DRA
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 ATF1504BE does not change when a new set of
configuration data is passed to the ATF1504BE 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.
5.4 ISP Programming Protection
The ATF1504BE 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 ATF1504BE devices are initially shipped in the erased state, thereby making them ready to
use for ISP.
12 ATF1504BE
3637B–PLD–1/08