36.5.4.3.3 8-bit Grayscale Mode

For 8-bit Grayscale mode, ISI_DATA[7:0] on the 12-bit data bus is the physical interface to the ISI. These bits are sampled and written to memory.

To enable 8-bit Grayscale mode, configure ISI_CFG2 as follows:

• Clear ISI_CFG2.GRAYSCALE.
• Clear ISI_CFG2.RGB_SWAP.
• Clear ISI_CFG2.COL_SPACE.
• Configure the field ISI_CFG2.YCC_SWAP to value 0.
• Configure the field ISI_CFG2.IM_VSIZE with the vertical resolution of the image minus 1.
• Configure the field ISI_CFG2.IM_HSIZE with the horizontal resolution of the image divided by 2. The horizontal resolution must be a multiple of 2.

The codec datapath is used to capture the 8-bit grayscale image. Use the following configuration:

• Set ISI_DMA_C_CTRL.C_FETCH.
• Configure ISI_DMA_C_DSCR.C_DSCR with the descriptor address.
• Write a one to the bit ISI_DMA_CHER.C_CH_EN.

  Table 36-11. Memory Mapping for 8-bit Grayscale Mode

  31	30	29	28	27	26	25	24
  Pixel 3
  23	22	21	20	19	18	17	16
  Pixel 2
  15	14	13	12	11	10	9	8
  Pixel 1
  7	6	5	4	3	2	1	0
  Pixel 0