EP3C16F256I7N Altera, EP3C16F256I7N Datasheet - Page 390

• Manufacturer Part Number: EP3C16F256I7N
• Description: Cyclone III
• Manufacturer: Altera

IEEE 1149.1 (JTAG) Boundary-Scan Testing for Cyclone III Devices
Figure 14–11. EXTEST Shift Data Register Waveforms
14–16
Cyclone III Device Handbook, Volume 1
TAP_STATE
TMS
TDO
TCK
TDI
SHIFT_IR
Instruction Code
EXTEST selects data differently than SAMPLE/PRELOAD. EXTEST chooses
data from the update registers as the source of the output and output
enable signals. Once the EXTEST instruction code is entered, the
multiplexers select the update register data. Thus, data stored in these
registers from a previous EXTEST or SAMPLE/PRELOAD test cycle can be
forced onto the pin signals. In the capture phase, the results of this test
data are stored in the capture registers and then shifted out of TDO during
the shift phase. New test data can then be stored in the update registers
during the update phase.
The EXTEST waveform diagram in
SAMPLE/PRELOAD waveform diagram, except for the instruction code.
The data shifted out of TDO consists of the data that was present in the
capture registers after the capture phase. New test data shifted into the
TDI pin appears at the TDO pin after being clocked through the entire
boundary-scan register.
BYPASS Instruction Mode
The BYPASS mode is activated when an instruction code of all ones is
loaded in the instruction register. This mode allows the boundary scan
data to pass the selected device synchronously to adjacent devices when
no test operation of the device is needed at the board level. The
waveforms in
once the TAP controller is in the SHIFT_DR state. In this state, data signals
are clocked into the bypass register from TDI on the rising edge of TCK
and out of TDO on the falling edge of the same clock pulse.
EXIT1_IR
UPDATE_IR
SELECT_DR
Figure 14–12
CAPTURE_DR
show how scan data passes through a device
Data stored in
boundary-scan
register is shifted
out of TDO.
Figure 14–11
Altera Corporation-Preliminary
After boundary-scan
register data has been
shifted out, data
entered into TDI will
shift out of TDO.
resembles the
SHIFT_DR
March 2007
UPDATE_DR
EXIT1_DR