Freescale Semiconductor e200z3 Reference Manual page 413

10.10.7 Error Handling
The Nexus3/Nexus2+ module handles various error conditions as described in the following sections.
10.10.7.1 AHB Read/Write Error
All address and data errors that occur on read/write accesses to the e200z3 AHB system bus return a
transfer error encoding on the p_hresp[1:0] signals. If this occurs, the following steps are taken:
1. The access is terminated without retrying, and RWCS[AC] is cleared.
2. RWCS[ERR] is set.
3. The error message is sent, TCODE = 8, indicating read/write error.
10.10.7.2 Access Termination
The following cases are defined for sequences of the read/write protocol that differ from those described
in the above sections.
1. If RWCS[AC] is set to start read/write accesses and invalid values are loaded into RWD or RWA,
an AHB access error may occur. This is handled as described above.
2. If a block access is in progress, all cycles are not completed, and the RWCS register is written. The
original block access is terminated at the boundary of the nearest completed access.
a) If RWCS[AC] is set, the next read/write access begins and the RWD can be
written to / read from.
b) If RWCS[AC] is cleared, the read/write access is terminated at the nearest completed access.
This method can be used to break block accesses or terminate them early.
10.10.7.3 Read/Write Access Error Message
The read/write access error message is sent out when an AHB system bus access error, read or write, has
occurred.
Error information is messaged out in the format shown in
Error Code (00011)
10.11 Nexus3/Nexus2+ Pin Interface
This section details the Nexus3/Nexus2+ pins and pin protocol.
The Nexus3/Nexus2+ pin interface provides the function of transmitting messages from the messages
queues to the external tools. It is also responsible for handshaking with the message queues.
Freescale Semiconductor
(5 bits) (4 bits)
Source Process
Fixed length = 15 bits
Figure 10-42. Error Message Format
e200z3 Power Architecture Core Reference Manual, Rev. 2
Figure 10-42:
(6 bits)
TCODE (001000)
Nexus3/Nexus2+ Module
10-47