SPRUIE9D May 2017 – May 2024 DRA74P , DRA75P , DRA76P , DRA77P
In addition to the Section 9.3.3.9.16, ISIF support circular buffer addressing. Figure 9-167 shows this circular buffer function.
Figure 9-167 ISS ISP ISIF Circular Buffer controlIf CBN=0, the circular buffer function is not used. The memory address is used as a linear space, and does not go back to the start address at CBN-th line.
Circular buffer function can be used in combination with Output Formatter. Since Output Formatter allows the line offset to be -4 to +4 lines, the address may go earlier than SAD after reset. SW should make sure to allocate memories for such case. See Figure 9-168
For circular buffer to work effectively, interrupt is available. After every CYN lines, an interrupt (isif_cb) is issued . This notifies how many lines in the circular buffer is filled.
This event (isif_cb) is also exposed to ICM, and ICM can use this as P_DONE. However, ISIF does not implement ICM handshake, and does not receive P_START signal.
Figure 9-168 ISS ISP ISIF Combination of Circular Buffer and Output Formatter