Interrupt Status Register

The Interrupt Status register (ISR) is described in Table: Interrupt Status Register (0x24) and captures the error and status information for the core.

Table 2-12: Interrupt Status Register (0x24)
Bits	Name	Reset Value	Access ⁽¹⁾	Description
31	Frame Received	0x0	R/W1C	Asserted when the Frame End (FE) short packet is received for the current frame
30	VCX Frame Error	0x0	RO	Asserted when the VCX Frame error is detected
29	RX_Skewcalhs	0x0	R/W1C	Asserted when rxskewcalhs is detected.
28	YUV420 WC Error	0x0	R/W1C	Asserted when the user-configured YUV420 word count value is less than the actual Y-line word count of the incoming data, which results in an internal buffer full condition. Note: Ensure the Y-line word count of the incoming data is at least 8 bytes less than the value configured in GUI to avoid this flag.
27	Pending write in internal FIFO	0x0	R/W1C	Indicates internal FIFO has insufficient clocks to process the packet. This happens in non-continuous clock mode if there are insufficient clocks to completely write the PPI data to internal FIFO. To resolve this, the user needs to increase the Tclk-post parameter in the transmitter. Incase this bit is seen set by default, write 1 to clear this bit after the rxbyteclkhs starts toggling.
26–23	Reserved	N/A	N/A	N/A
22	Word Count (WC) corruption	0x0	R/W1C	Asserted when WC field of packet header corrupted and core receives less bytes than indicated in WC field. Such a case can occur only where more than 2-bits of header are corrupted which ECC algorithm cannot report and the corruption is such that the ECC algorithm reports a higher Word Count (WC) value as part of ECC correction. In such case core limits processing of the packet on reduced number of bytes received through PPI interface.
21	Incorrect lane configuration	0x0	R/W1C	Asserted when Active lanes is greater than Maximum lanes in the protocol configuration register
20	Short packet FIFO full	0x0	R/W1C	Active-High signal asserted when the short packet FIFO full condition detected
19	Short packet FIFO not empty	0x0	R/W1C	Active-High signal asserted when short packet FIFO not empty condition detected
18	Stream line buffer full	0x0	R/W1C	Asserts when the line buffer is full ⁽²⁾
17	Stop state	0x0	R/W1C	Active-High signal indicates that the lane module is currently in Stop state ⁽³⁾
16	Reserved	N/A	N/A	N/A
15	Reserved	N/A	N/A	N/A
14	Reserved	N/A	N/A	N/A
13	SoT error (ErrSoTHS)	0x0	R/W1C	Indicates Start-of-Transmission (SoT) error detected ⁽³⁾
12	SoT sync error (ErrSotSyncHS)	0x0	R/W1C	Indicates SoT synchronization completely failed ⁽³⁾
11	ECC 2-bit error (ErrEccDouble)	0x0	R/W1C	Asserted when an ECC syndrome is computed and two bit errors detected in the received packet header
10	ECC 1-bit error (Detected and Corrected) (ErrEccCorrected)	0x0	R/W1C	Asserted when an ECC syndrome was computed and a single bit error in the packet header was detected and corrected
9	CRC error (ErrCrc)	0x0	R/W1C	Asserted when the computed CRC code is different from the received CRC code
8	Unsupported Data Type (ErrID)	0x0	R/W1C	Asserted when a packet header is decoded with an unrecognized or not implemented data ID
7	Frame synchronization error for VC3 (ErrFrameSync)	0x0	R/W1C	Asserted when an FE is not paired with a Frame Start (FS) on the same virtual channel ⁽⁴⁾
6	Frame level error for VC3 (ErrFrameData)	0x0	R/W1C	Asserted after an FE when the data payload received between FS and FE contains errors. The data payload errors are CRC errors.
5	Frame synchronization error for VC2 (ErrFrameSync)	0x0	R/W1C	Asserted when an FE is not paired with a FS on the same virtual channel ⁽⁴⁾
4	Frame level error for VC2 (ErrFrameData)	0x0	R/W1C	Asserted after an FE when the data payload received between FS and FE contains errors. The data payload errors are CRC errors.
3	Frame synchronization error for VC1 (ErrFrameSync)	0x0	R/W1C	Asserted when an FE is not paired with a FS on the same virtual channel ⁽⁴⁾
2	Frame level error for VC1 (ErrFrameData)	0x0	R/W1C	Asserted after an FE when the data payload received between FS and FE contains errors. The data payload errors are CRC errors.
1	Frame synchronization error for VC0 (ErrFrameSync)	0x0	R/W1C	Asserted when a FE is not paired with a FS on the same virtual channel ⁽⁴⁾
0	Frame level error for VC0 (ErrFrameData)	0x0	R/W1C	Asserted after an FE when the data payload received between FS and FE contains errors. The data payload errors are CRC errors.
Notes: 1. W1C = Write 1 to clear. 2. In a line buffer full condition, reset the core using the external reset, video_aresetn. 3. Reported through the PPI. 4. An ErrSotSyncHS error also generates this error signal. 5. Short packet and line buffer FIFO full conditions take a few clock periods to reflect in the register clock domain from the core clock domain due to Clock Domain Crossing (CDC) blocks. 6. All PPI signals captured in the ISR take a few clock periods to reflect in the register clock domain from the PPI clock domain due to CDC blocks. 7. Frame level errors due to ErrSotSyncHS are mapped to the recent VC processed by the ECC block of the core. 8. Set conditions take priority over the reset conditions for the ISR bits. 9. Signal names in brackets are defined in the MIPI Alliance Standard for Camera Serial Interface CSI-2 [Ref 1] .

Table 2-13: Incorrect Lane Configuration
Set Condition(s)	Set by the core when incorrect lane configuration is programmed. Ex: Maximum available lanes =2 and “Active lanes” configured as 3
Reset Sequence	Write 1 to clear this bit.
Priority	Set condition takes priority over reset sequence.
Impact	This is a core configuration error and the core cannot function as desired. This error should be corrected before proceeding further.

Table 2-14: Stream Line Buffer Full
Set Condition(s)	Set by the core when the line buffer storing pixel data is full.
Reset Sequence	Write 1 to clear this bit.
Priority	Set condition takes priority over reset sequence.
Impact	Core reports this condition on stream interface using an error indication on the TUSER[1] port if a partial packet is being written to line buffer. Because PPI does not allow back pressure, you need to ensure that this condition does not occur.

Table 2-15: Control Error, Escape Entry Error, Escape Ultra Low Power Mode, Stopstate
Set Condition(s)	Set by the core when the condition for the corresponding signal as defined in the MIPI CSI-2 specification [Ref 1] is seen, reported through the PPI interface.
Reset Sequence	Write 1 to clear this bit.
Priority	Set condition takes priority over reset sequence.
Impact	Current packet being processed does not have any impact.

Table 2-16: SoT Error
Set Condition(s)	Set by the core when the current packet being processed has Start-of-Transmission (SoT) Error reported through PPI Interface.
Reset Sequence	Write 1 to clear this bit.
Priority	Set condition takes priority over reset sequence.
Impact	Current packet under process does not have any impact as synchronization is still achieved. This is considered to be a “soft error” in the leader sequence and confidence in the payload data is reduced.

Table 2-17: SoT Sync Error
Set Condition(s)	Set by the core when current packet being processed has Start-of-Transmission Synchronization Error reported through PPI interface.
Reset Sequence	Write 1 to clear this bit.
Priority	Set condition takes priority over reset sequence.
Impact	The current packet being processed is not processed further. The core waits for the next packet to process.

Table 2-18: ECC 2-Bit Error
Set Condition(s)	Set by the core when an ECC syndrome was computed and two bit-errors are detected in the received Packet Header.
Reset Sequence	Write 1 to clear this bit.
Priority	Set condition takes priority over reset sequence.
Impact	Current packet being processed is not processed further as WC is not usable, and thus the packet end cannot be estimated.The core waits for the next packet to process.

Table 2-19: ECC 1-Bit Error
Set Condition(s)	Set by the core when an ECC syndrome was computed and a single bit-error in the Packet Header was detected and corrected.
Reset Sequence	Write 1 to clear this bit.
Priority	Set condition takes priority over reset sequence.
Impact	Current packet being processed does not have any impact.

Table 2-20: CRC Error
Set Condition(s)	Set by the core when the computed CRC code is different than the received CRC code.
Reset Sequence	Write 1 to clear this bit.
Priority	Set condition takes priority over reset sequence.
Impact	Current packet being processed does not have any impact, but the payload might be corrupted.

Table 2-21: Unsupported Data Type
Set Condition(s)	Set by the core when a Packet Header is decoded with an unrecognized or un-implemented data ID.
Reset Sequence	Write 1 to clear this bit.
Priority	Set condition takes priority over reset sequence.
Impact	Current packet being processed is not processed further. The core waits for the next packet to process.

Table 2-22: Frame Synchronization Error
Set Condition(s)	Set by the core when a Frame End (FE) is not paired with a Frame Start (FS) on the same virtual channel. An ErrSotSyncHS should also generate this error signal.
Reset Sequence	Write 1 to clear this bit.
Priority	Set condition takes priority over reset sequence.
Impact	Based on the different sources for this error packet might or might not be processed (that is, stored in the line buffer).

Table 2-23: ErrFrameSync Sources
Source	Impact on Packet Processing
FS followed by FS	Processed
ErrEccDouble	Not processed
FE followed FE	Processed
ErrSotSyncHS	Not processed

Tables 2-13 to 2-24 provide detailed information about the bits in Table: Interrupt Status Register (0x24) .

Interrupt Status Register - 5.1 English

MIPI CSI-2 Receiver Subsystem Product Guide (PG232)