![](http://datasheet.mmic.net.cn/120000/MC68349FT16_datasheet_3559370/MC68349FT16_365.png)
9- 4
MC68349 USER’S MANUAL
MOTOROLA
Table 9-1. Boundary Scan Control Bits
Name
Bit Number
Name
Bit Number
Name
Bit Number
irq7.ctl
49
cs0.ctl
63
ab27.ctl
96
irq6.ctl
51
ab.ctl
86
ab28.ctl
98
irq5.ctl
53
berr.ctl
87
ab29.ctl
100
cs3.ctl
55
db.ctl
88
ab30.ctl
102
cs2.ctl
57
ab24.ctl
90
ab31.ctl
104
cs1.ctl
59
ab25.ctl
92
modck.ctl
132
irq3.ctl
61
ab26.ctl
94
ifetch.ctl
135
Boundary scan bit definitions are shown in Table 9-2. The first column in Table 9-2 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 140.
The second column references one of the five MC68349 cell types depicted in Figures
9-3–9-7, 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-high level for irq7.ctl (bit 49) is logic zero since the cell type is IO.Ctl0. The active
level for ab.ctl (bit 86) is logic one, since the cell type is IO.Ctl1. IO.Ctl0 (see Figure 9-6)
differs from IO.Ctl1 (see Figure 9-5) by an inverter in the output enable path.
The fourth column lists the pin type: 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 9-7.
These bits are controlled by one of the two bits shown in Figures 9-5 and 9-6. 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 9-
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.