12-32
ColdFire CF4e Core User’s Manual
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Integration Connections
12.4 Integration Connections
The three mtmod test input signals must be routed from the package pins to the
cf4_core_kbus_tcu. This can be a direct connection from the package pins to the CF4eCore
or another form of dedicated chip-level test selection that creates the three mtmod signals
in a chip-level test controller.
Rules for connecting the CF4eCore scan interface are straightforward. When the mtmod
encoding distributed to the CF4eCore is either 3 (burn-in scan mode) or 4 (production scan
mode), the si and tbsi scan inputs must be connected to package pins as inputs; so and tbso
scan outputs must be connected to package pins as outputs; and se, tbte, tbsei, and tbseo
scan shift control signals must be connected to package pins as inputs.
The CF4e parallel scan connections can be gated off whenever they are not being used in a
scan mode (when encodings 3 and 4 are not selected). At that time, parallel scan inputs must
be driven to a logic 0 and parallel scan outputs must be ignored.
On the other hand, the CF4e test wrapper scan connections can be used across several test
modes. Because the test wrapper is shared by CF4e and non-CF4e logic, access to the CF4e
test wrapper connections must be provided in both core and non-core test modes. This
should include any CF4e core scan test mode, any non-core logic scan test mode, and any
non-core logic test mode that wishes to drive or view the CF4e interface.
12.5 Test Controller
The CF4e test controller unit (TCU) contains the head and tail registers of all the scan
chains in the design. A head or tail register is the first or last register in a scan chain,
respectively. Head and tail registers are used only for scan shift operations and have no
functional use. The TCU decodes the three Motorola test mode signals (mtmod[2:0].) The
encodings are described in the following section.
12.5.1 MTMOD[2:0] Encodings
The CF4e has a set of three test mode pins (mtmod[2:0]) that control all test modes of the
core. Table 12-6 describes the encoding for these signals.
Table 12-6. CF4e Motorola Test Mode Encodings
Hex
MTMOD[2:0]
Mode or Action
0
000
Functional mode
1
001
Functional mode with JTAG mode active
2
010
PLL test mode
3
011
Burn-in scan mode
4
100
Production scan mode
5
101
Production BIST (PBIST)
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