10-4
MC68341 USER’S MANUAL
MOTOROLA
associated groups of bidirectional and three-state pins. The control bits and their bit
positions are listed in Table 10-1.
Table 10-1. Boundary Scan Control Bits
Name
Bit Number
Name
Bit Number
Name
Bit Number
ifetch.ctl
152
ab31.ctl
114
berr.ctl
97
modck.ctl
149
ab30.ctl
112
ab.ctl
96
irq1.ctl
131
ab29.ctl
110
cs0.ctl
74
irq2.ctl
129
ab28.ctl
108
tout.ctl
44
irq3.ctl
127
ab27.ctl
106
pcs0.ctl
14
irq4.ctl
125
ab26.ctl
104
pcs1.ctl
11
irq5.ctl
123
ab25.ctl
102
miso.ctl
8
irq6.ctl
121
ab24.ctl
100
mosi.ctl
5
irq7.ctl
119
db.ctl
98
sck.ctl
2
Boundary scan bit definitions are shown in Table 10-2. The first column in Table 10-2
defines the bit's ordinal position in the boundary scan register. The shift register bit
nearest TDO (i.e., first to be shifted out) is defined as bit 0; the last bit to be shifted out is
154.
The second column references one of the five MC68341 cell types depicted in Figures
10-3–10-7, which describe the cell structure for each type.
The third column lists the pin name for all pin-related bits or defines the name of
bidirectional control register bits. The active level of the control bits (i.e., output driver on)
is defined by the last digit of the cell type listed for each control bit. For example, the
active level for irq2.ctl (bit 129) is logic zero since the cell type is IO.Ctl0. The active level
for ab.ctl (bit 96) is logic one, since the cell type is IO.Ctl1. IO.Ctl0 (see Figure 10-6)
differs from IO.Ctl1 (see Figure 10-5) by an inverter in the output enable path.
The fourth column lists the pin type: TS-Output indicates a three-state output pin, I/O
indicates a bidirectional pin, and OD-I/O denotes an open-drain bidirectional pin. An open-
drain output pin has two states: off (high impedance) and logic zero.
The last column indicates the associated boundary scan register control bit for
bidirectional, three-state, and open-drain output pins.
Bidirectional pins include a single scan bit for data (IO.Cell) as depicted in Figure 10-7.
These bits are controlled by one of the two bits shown in Figures 10-5 and 10-6. The value
of the control bit determines whether the bidirectional pin is an input or an output. One or
more bidirectional data bits can be serially connected to a control bit as shown in Figure
10-8. Note that, when sampling the bidirectional data bits, the bit data can be interpreted
only after examining the IO control bit to determine pin direction.
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Freescale Semiconductor, Inc.
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