49.5.4.3.3 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 49-11. Memory Mapping for 8-bit Grayscale Mode
Bit 31 30 29 28 27 26 25 24
Pixel 3
Bit 23 22 21 20 19 18 17 16
Pixel 2
Bit 15 14 13 12 11 10 9 8
Pixel 1
Bit 7 6 5 4 3 2 1 0
Pixel 0