3. Processor Bus Interface
98
PowerSpan II User Manual
80A1010_MA001_09
Integrated Device Technology
www.idt.com
The data parity bits, PB_DP[0:7], are driven to the correct values for even or odd parity by the PB slave
during reads and checked during writes.
The detection of a data parity error does not affect the transaction and data is still forwarded to the
destination bus. See
“Interrupt Handling” on page 145
for a full
description of error logging support and associated interrupt mapping options.
Special Parity Requirements with the PowerQUICC II
Address parity and data parity must be specially programmed in a joint
PowerSpan II and PowerQUICC II application.
In a joint application all memory accesses from the PowerQUICC II to
PowerSpan II must be routed through the internal memory controller on the PowerQUICC II. When the
data is passed through the memory controller both address parity and data parity can be used in the
system.
If accesses do not pass through the memory controller of the PowerQUICC II before reaching
PowerSpan II, and PowerSpan II has either or both address and data parity enabled, then PowerSpan II
reports parity errors on the transaction.
To enable or disable address parity in PowerSpan II, set the Address Parity Enable (AP_EN) bit in the
“Processor Bus Slave Image x Control Register” on page 287
.
To enable or disable data parity in PowerSpan II, set the Data Parity Enable (DP_EN) bit in the
“Processor Bus Slave Image x Control Register” on page 287
.
3.3.3
Terminations
The following sections describe the terminations and exception handling supported by PowerSpan II.
3.3.3.1
PB Slave Termination
The PB slave uses the following pins to indicate termination of individual data beats and/or data tenure:
•
Address Retry (PB_ARTRY_): This signal terminates the entire address and data tenure and
schedules the transaction to be rerun. No data is transferred, even if asserted coincidentally with
PB_TA/PB_DVAL_, as in the case of a third party address retry.
•
Transfer Acknowledge (PB_TA_): This signal is asserted by the PowerSpan II PB Slave to indicate
the successful transfer of a single beat transaction, or each 8-byte quantity transferred for a burst.
PB_D[40:47]
PB_DP[5]
PB_D[48:55]
PB_DP[6]
PB_D[56:63]
PB_DP[7]
Table 19: PowerSpan II PB Data Parity Assignments
Data Bus
Data Parity