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 1. 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 |