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Sentinel65X-Handbook
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Work on fleshing out sections

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Kyle Cardoza 2024-03-24 03:35:36 -04:00
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Audio & Video.md
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@ -15,9 +15,13 @@ The video generation is done using two independent tile/bitmap layers, and a thi
![12-bit RGB image of a parrot](images/RGB_12bits_palette_sample_image.png) ![12-bit colour palette](images/RGB_12bits_palette_color_test_chart.png)
Each of the tile/bitmap layers is fully indepentent for content, mode, scrolling, etc. Both layers support two special modes useful for text displays, in 16 and 256 colours.
There are enough sprites supported to act as a third bitmap layer, should the programmer wish to make use of sprites in that manner.
## Audio
The VERA FPGA core produces audio output in i2S format, which is fed to the A/V port for conversion into an analog or digital format suitable for the target display device.
The VERA FPGA core produces audio output in [I²S](https://en.wikipedia.org/wiki/I²S) format, which is fed to the A/V port for conversion into an analog or digital format suitable for the target display device.
Audio is generated using a 16-voice stereo programmable sound generator, with each voice able to generate sounds independently, with the waveform for each chosen freely from among Pulse, Sawtooth, Triangle, and Noise.
@ -86,7 +90,7 @@ The `ADDR0_H` and `ADDR1_H` registers control the low byte of the selected addre
Bit 0 of the `ADDRx_H` is bit 16 of the address of the data port selected by `ADDRSEL`. Bits 1 and 2 of `ADDRx_H` are unused. Bit 3 is called `DECR0` or `DECR1`; when this bit is clear, the address of the selected data port will increment by the amount set with bits 4-7, called `INCR0` or `INCR1`, according to the table below. When `DECR0` or `DECR1` is set, then the address will _decrement_ by the same amount when the matching data register is read from or written to.
| `INCR` value | Address Increment |
| -------------: | ---------------: |
| :-------------: | :---------------: |
| 0 | 0 |
| 1 | 1 |
| 2 | 2 |
@ -366,6 +370,10 @@ The layer position value determines the drawing order of the sprite relative to
| 2 | Between layer 0 and 1 |
| 3 | Above layer 1 |
The horizontal and vertical flip bits, as you would expect, flip the sprite's bitmap along the horizontal and vertical axes, respectively.
The palette offset is used to translate colour values from the sprite bitmap data, where those values are between 1 and 15. Such values are modified by adding the product of 16 and the palette offset.
## 16-Bit Reads/Writes
With appropriate configuration of registers, it is possible to perform sequential 16-bit reads and writes to VERA address space: