Nexus3/ Module
e200z3 Power Architecture Core Reference Manual, Rev. 2
Freescale Semiconductor
10-49
The Nexus auxiliary port arbitration pins are used when the Nexus3/ module is implemented in a
multiple Nexus SoC that shares a single auxiliary output port. The arbitration is controlled by an SoC-level
Nexus port control module (NPC). Refer to
Section 10.13, “Auxiliary Port Arbitration,”
for details on
Nexus port arbitration.
10.11.2 Pin Protocol
The protocol for the e200z3 processor transmitting messages through the auxiliary pins is accomplished
with the MSEO pin function outlined in
. Both single- and dual-pin cases are shown.
nex_mseo_b[1:0] is used to signal the end of variable-length packets, and not fixed length packets.
nex_mseo_b[1:0] is sampled on the rising edge of the Nexus3/ clock, nex_mcko.
nex_evto_b
O
Event out. An output whose assertion indicates that one of two events has occurred
based on the bits in DC1[EOC].
nex_evto_b
is held asserted for 1 cycle of
nex_mcko:
• One (or more) watchpoints has occurred (from Nexus1) and EOC = 00
• Debug mode was entered (
jd_debug_b asserted from Nexus1) and EOC = 01
nex_evti_b
I
Event in. An input whose assertion initiates one of two events based on DC1[EIC] (if
the Nexus module is enabled at reset):
• Program trace and data trace synchronization messages (provided program trace
and data trace are enabled and EIC = 00).
• Debug request to e200z3 Nexus1 module (provided EIC = 01 and this feature is
implemented).
Table 10-32. Nexus Port Arbitration Signals
Nexus Port
Arbitration Pins
Input/
Output
Description of Arbitration Pins
nex_aux_req[1:0]
O
Nexus auxiliary request. Output signals indicating to an SoC level Nexus arbiter a request
for access to the shared Nexus auxiliary port in a multiple Nexus implementation. The
priority encodings are determined by how many messages are currently in the message
queues, see
).
nex_aux_busy
O
Nexus auxiliary busy. An output signal to an SoC level Nexus arbiter indicating that the
Nexus3/ module is currently transmitting its message after being granted the
Nexus auxiliary port.
npc_aux_grant
I
Nexus auxiliary grant. An input from the SoC level Nexus port controller (NPC) indicating
that the auxiliary port has been granted to the Nexus3/ module to transmit its
message.
ext_multi_nex_sel
I
Multiple Nexus select. A static signal indicating that the Nexus3/ module is
implemented within a multiple Nexus environment. If set, port control and arbitration is
controlled by the SoC-level arbitration module (NPC).
Table 10-33. MSEO Pin(s) Protocol
nex_mseo_b Function
Single
nex_mseo_b data (serial)
Dual
nex_mseo_b[1:0] data
Start of message
1–1–0
11–00
End of message
0–1–1–(more ones)
00 (or 01)–11–(more ones)
Table 10-31. Nexus3/ Auxiliary Pins (continued)
Auxiliary Pin
I/O
Description of Auxiliary Pins
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