Module Operation
484
SPNU503C – March 2018
Copyright © 2018, Texas Instruments Incorporated
Cyclic Redundancy Check (CRC) Controller Module
14.2.10.6 Interrupt Offset Register
CRC Controller only generates one interrupt request to interrupt manager. A interrupt offset register is
provided to indicate the source of the pending interrupt with highest priority.
shows the offset
interrupt vector address of each interrupt condition in an ascending order of priority.
Table 14-3. Interrupt Offset Mapping
Offset Value
Interrupt Condition
0
Phantom
1h
Ch1 CRC Fail
2h
Ch2 CRC Fail
3h-8h
Reserved
9h
Ch1 Compression Complete
Ah
Ch2 Compression Complete
Bh-10h
Reserved
11h
Ch1 Overrun
12h
Ch2 Overrun
13h-18h
Reserved
19h
Ch1 Underrun
1Ah
Ch2 Underrun
1Bh-20h
Reserved
21h
Ch1 Timeout
22h
Ch2 Timeout
23h-24h
Reserved
14.2.10.7
Error Handling
When an interrupt is generated, host CPU should take appropriate actions to identify the source of error
and restart the respective channel in DMA and CRC module. To restart a CRC channel, the user should
perform the following steps in the ISR:
1. Write to software reset bit in CRC_CTRL register to reset the respective PSA Signature Register.
2. Reset the CHx_MODE bits to 00 in CRC_CTRL register as Data capture mode.
3. Set the CHx_MODE bits in CRC_CTRL register to desired new mode again.
4. Release software reset.
The host CPU should use byte write to restart each individual channel.
14.2.11 CPU Data Trace
CRC channel 1 can be used to snoop Flash, System RAM and Peripheral Bus Master Data buses.
However, at any one point only one bus is snooped. It is possible to disable the snooping of any of the
buses by programming CRC_BUS_SEL register. While snooping the data, there is a priority scheme
implemented between the buses. Peripheral Bus Master has the highest priority followed by Flash, Even
System RAM and Odd System RAM. For each data read by CPU on its data bus the same data is
compressed in the PSA Signature Register. A write to PSA Signature Register does not get compressed.
Therefore, it is possible to write a seed value into PSA Signature Register before the bus snooping takes
place. During data trace mode, all interrupts and DMA request logic are inactive. For non double word
read on the data bus, all un-selected byte lanes are padded with zero during compression.