SPRUIE9D May 2017 – May 2024 DRA74P , DRA75P , DRA76P , DRA77P
From the paxel starting coordinate (the H3A_AFPAXSTART[27:16] PAXSH and H3A_AFPAXSTART[11:0] PAXSV bit fields) specifies the starting point of the paxel grid, with respect to first pixel of the input image frame.
The paxel starting coordinate also indicates which color pixels are extracted if VF is enabled (that is, if H3A_PCR[20] AF_VF_EN = 1). Normally, either Gr or Gb is used for AF, but it is not important to the hardware whether it is red, green, or blue. If VF is not enabled, then the red, green, and blue pixel extraction is controlled by the H3A_PCR[13:11] RGBPOS bit field to extract the correct colors from the input stream. Figure 9-115 shows the available options for this bit field. The red and blue pixel positions are interchangeable. For each 2 × 2 grid, the green pixels are summed to create a single value. Because of this, the amplitude of the green output contains 2 pixels, while the red and blue outputs each contain 1 pixel.
Each paxel is H3A_AFPAX1[23:16] PAXW × H3A_AFPAX1[7:0] PAXH (width × height) pixels. Inside each paxel, horizontal FV can skip lines, operating on one every H3A_AFPAX2[16:13] AFINCV lines. Vertical FV can skip columns, operating on one every H3A_AFPAX2[20:17] AFINCH columns. Up to 32 columns are supported for each paxel. If floor (PAXW/AFINCH) >= 32, only the first 32 designated columns are operated on. Because PAXW, PAXH, AFINCV, and AFINCH are all even numbers, AF always operates on the same green color, Gr or Gb. IIR filters for the horizontal FVs start operation at column H3A_AFIIRSH[11:0] IIRSH.
Figure 9-116 shows the ISS ISP H3A horizontal/vertical fv paxel configuration.
(H3A_AFPAXSTART[27:16] PAXSH) + (H3A_AFPAX2[5:0] PAXHC) × (H3A_AFPAX1[23:16] PAXW) <= [(Frame width on VP) – (H3A_LINE_START[15:0] LINE_START)] <= 2816
Table 9-195 lists the bit fields that configure the size and number of paxels.
Bit Field | Bit Width | Description |
---|---|---|
H3A_AFPAX1[23:16] PAXW | 8 | Paxel width (in pixels) |
H3A_AFPAX1[7:0] PAXH | 8 | Paxel height (in lines) |
H3A_AFPAX2[5:0] PAXHC | 6 | Paxel count for horizontal direction |
H3A_AFPAX2[12:6] PAXVC | 7 | Paxel count for vertical direction |
H3A_AFPAX2[16:13] AFINCV | 4 | Line increments in a paxel |
H3A_AFPAX2[20:17] AFINCH | 4 | Column increments in a paxel |
H3A_AFPAXSTART[27:16] PAXSH | 12 | Paxel start position H |
H3A_AFPAXSTART[11:0] PAXSV | 12 | Paxel start position V |
H3A_AFIIRSH[11:0] IIRSH | 12 | IIR filter start position |
The H3A AF engine also has an option for an advanced or normal stats collection mode. When 0xCA00 is written to the H3A_ADVANCED[31:15] ID bit field, then H3A_ADVANCED[0] AF_MODE can be used to toggle between normal and advanced AF stats collection mode. When the advanced AF stats collection mode is enabled, the ZEROS section of the AF paxel packet is filled with the sum of the maximum FVs, regardless of the color, from HFV_1 and HFV_2.