Parity Memory
1221
SPNU503C – March 2018
Copyright © 2018, Texas Instruments Incorporated
Multi-Buffered Serial Peripheral Interface Module (MibSPI) with Parallel Pin
Option (MibSPIP)
24.11 Parity Memory
The parity portion of multi-buffer RAM is not accessible by the CPU during normal operating modes.
However, each read or write operation to the control/data/status portion of the multi-buffer RAM causes
reads/writes to the parity portion as well.
•
Each write to the multi-buffer RAM (either from the Peripheral interface or by the MibSPI itself) causes
a write operation to the parity portion of RAM simultaneously to update the equivalent parity bits.
•
Each read operation from the multi-buffer RAM (either from the Peripheral interface or by the MibSPI
itself) causes a read operation from the parity portion of the RAM for parity comparison purpose.
•
Reads/Writes to multi-buffer RAM can either be caused by any CPU/DMA accesses or by the
sequencer logic of MibSPI itself.
•
Incase of Parity error ESM module is notified to generate MIBSPI Parity ESM interrupt. User can check
the error status and address location captured in the UERRSTAT and UERRADDRx registers
respectively.
For testing the parity portion of the multi-buffer RAM, which is a 4-bit field per word address (1 bit per
byte), a separate parity memory test mode is available. Parity memory test mode can be enabled and
disabled by the PTESTEN bit in the UERRCTRL register.
During the parity test mode, the parity locations are addressable at the address between
RAM_BAS 0x400h and RAM_BAS 0x7FFh. Each location corresponds,
sequentially, to each TXRAM word, then to each RXRAM word. See
for a diagram of the
memory map of parity memory during normal operating mode and during parity test mode.
During parity test mode, after writing the data/control portion of the RAM, the parity locations can be
written with incorrect parity bits to intentionally cause parity errors.
See the device-specific data sheet to get the actual base address of the multi-buffer RAM.
NOTE:
The RX_RAM_ACCESS bit can also be set to 1 during the parity test mode to be enable
writes to RXRAM locations. Both parity RAM testing and RXRAM testing can be done
together.
There are 4 bits of parity corresponding to each of the 32-bit multi-buffer locations. Individual bits in the
parity memory are byte-addressable in parity test mode. See the example in
for further
details.
NOTE:
Polarity of the parity (odd/even) varies by device. In some devices, a control register in the
system module can be used to select odd or even parity.