CY7C0430V
PRELIMINARY
27
Once the entire MBIST sequence is completed, supplying ex-
tra TCK or CLKBIST cycles will have no effect on the MBIST
controller state or the pass-fail status.
Debug Mode
With the RUNBIST instruction loaded and the MCR loaded
with the value of “01”, and the FSM transitions to
RUN_TEST/IDLE state, the MBIST goes into RUNBIST-debug
mode. The debug mode will be used to provide complete fail-
ure analysis information at the board level. It is recommended
that the user runs the non-debug mode first and then the de-
bug mode in order to save test time and to set an upper bound
on the number of scan outs that will be needed. The failure
data will be scanned out automatically once a failure occurs
using the JTAG TAP interface. The failure data will be repre-
sented by a 100-bit packet given below. The 100-bit Memory
debug Register (MDR) will be connected between TDI and
TDO, and will be shifted out on TDO, which is synchronized to
TCK.
Figure 3 is a representation of the 100-bit MDR packet. The
packet follows a 2-bit header that has a logic “1” value, and
represents two TCK cycles. MDR[97:26] represent the BIST
comparator values of all four ports (each port has 18 data
lines). A value of “1” indicates a bit failure. The scanned out
data is from MSB to LSB. MDR[25:10] represent the failing
address (MSB to LSB). The state of the BIST controller is
scanned out using MDR[9:4]. Bit 2 is the Test Done bit. A “0”
in bit 2 means test not complete. The user has to monitor this
bit at every packet to determine if more failure packets need to
be scanned out at the end of the BIST operations. If the value
is “0” then BIST must be repeated to capture the next failing
packet. If it is “1,” it means that the last failing packets have
been scanned out. A trailer similar to the header represents
the end of a packet.
MCR_SCAN
This instruction will connect the Memory BIST Control Regis-
ter (MCR) between TDI and TDO. The default value (upon
master reset) is “00”. Shift_DR state will allow modifying the
MCR to extend the MBIST functionality.
MBIST Control States
Thirty-five states are listed in Table 7. Four data algorithms are
used in debug mode: moving inversion (MIA), march_2 (M2A),
checkerboard (CBA), and unique address algorithm (UAA).
Only Port 1 can write MIA, M2A, and CBA data to the memory.
All four ports can read any algorithm data from the QP mem-
ory. Ports 2, 3, and 4 will only write UAA data.
Boundary Scan Cells (BSC)
Table 9 lists all QuadPort I/Os with their associated BSC. No-
tice that the cells have even numbers. Every I/O has two
boundary scan cells. Bidirectional signals (address lines, data-
lines) require two cells so that one (the odd cell) is used to
control a three-state buffer. Input only and output only signals
have an extra dummy cell (odd cells) that are used to ease
device layout.
1
1
1
1
97
99
98
P4_IO(17-9)
P3_IO(17-9)
P1_IO(17-9)
P2_IO(17-9)
P4_IO(8-0)
P3_IO(8-0)
P1_IO(8-0)
P2_IO(8-0)
A(15-0)
MBIST_State
P/F
62
61
26
25
10
9
4
3
2
10
TD
Figure 3. MBIST Debug Register Packet
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