# GC9107 Readme

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## Table of contents

* [Overview](#overview)
* [Test](#test)
* [Software](#software)
  * [User Options](#user-options)
* [Hardware](#hardware)

## Overview

* Name: GC9107
* Description:

C++ Raspberry pi PICO  library for a TFT SPI LCD, GC9107  Driver.

The GC9107 is a 262,144-color single-chip SOC driver for a-TFT liquid crystal display with resolution of 128RGBx160dots, comprising a 384-channel source driver, a 160-channel gate driver, 46,080 bytes GRAM for graphic display data of 128RGBx160 dots, and power supply circuit.

1. Power modes, Invert, Scroll, Rotate, Bitmaps supported.
2. Hardware & software SPI
3. Tested on 60x160 Bar Display

* [DataSheet](https://www.buydisplay.com/download/ic/GC9107.pdf)

## Test

There are example files included. User picks the one they want
by editing the CMakeLists.txt :: add_executable(${PROJECT_NAME}  section.
Comment in one path and one path only.

| Filename | Function | Note |
| --- | --- | --- |
| hello | Hello world portrait | --- |
| hello_90 | Hello world landscape | --- |
| frame_buffer | Testing frame Buffer mode | dislib16_ADVANCED_SCREEN_BUFFER_ENABLE must be enabled user option 2 |
| bmp_data | bitmaps tests | Bitmap data is stored in arrays on PICO |
| text_graphics_functions | Text + Graphics + Functions | --- |

## Software

### User Options

In the main.cpp example files. There are  sections in "Setup()" function
where user can make adjustments to select for SPI type used, PCB type used and screen size.

0. USER OPTION 0 SPI_SPEED + TYPE
1. USER OPTION 1 GPIO
2. USER OPTION 2 SCREEN SECTION
3. USER OPTION 3 OFFSET'S

#### USER OPTION 0 SPI SPEED + TYPE

Here the user can pass the SPI Bus freq in kiloHertz, Currently set to 8 Mhz.
Max SPI speed on the PICO is 62.5Mhz.
There is a file with SPI test results for the FPS tests in extra/doc folder.
2nd parameter is the SPI interface(spi0 spi1 etc).

If users wants software SPI just call this method
with just one argument for the optional GPIO software uS delay,
which by default is zero. Setting this higher can be used to slow down Software SPI
which may be beneficial in  some setups.

#### USER OPTION 1 GPIO

The 5 GPIO pins used, the clock and data lines must be the clock and data lines
of spi interface chosen in option 0 if using hardware SPI.

#### USER OPTION 2 Screen size

In the main.cpp file, in USER OPTION 2 .
User can adjust Display size (width & height) in pixels, memory base
and colour order (RGB or BGR)

There are two memory base variants called "Display data GRAM mapping" in datasheet
Which I refer to as model A and B, These require different init routines.

1. 128x128 mapping (MEMORY_BASE_GM_128x128)
2. 128x160 mapping (MEMORY_BASE_GM_128x160)

#### USER OPTION 2 Screen offsets

In addition here are number of different truncated displays on market.
These truncated displays require different offset's.
These displays have panel sizes smaller than available Video RAM.
Known displays types on market with GC9107 controller.
Note: The offsets for untested devices are estimates and may be incorrect.

| Display Type | Memory Base | VRAM size (WbyH) | Offsets rotation | Tested |
| --- | --- | --- | --- | --- |
| 128x128 Square | MEMORY_BASE_GM_128x128 A | 128 , 128 | 0,0 | No device |
| 128x115 Round Truncated | MEMORY_BASE_GM_128x128 A | 128 , 128 | 0,13 ? | No device |
| 60x160 Truncated | MEMORY_BASE_GM_128x160 B | 128 , 160 | 34,0 | YES! |
| 96x160 Truncated | MEMORY_BASE_GM_128x160 B | 128 , 160 | 16,0? | No device |
| 128x160 Full | MEMORY_BASE_GM_128x160 B | 128 , 160 | 0,0 | No device |

Example Offset calculation for a truncated display(60x160) is as follows.

[![ offsets ](https://github.com/gavinlyonsrepo/displaylib_16bit_PICO/blob/main/extra/image/gc91.png)](https://github.com/gavinlyonsrepo/displaylib_16bit_PICO/blob/main/extra/image/gc91.png)

## Hardware

[![ display pic ](https://github.com/gavinlyonsrepo/displaylib_16bit_PICO/blob/main/extra/image/gc92.png)](https://github.com/gavinlyonsrepo/displaylib_16bit_PICO/blob/main/extra/image/gc92.png)

Connections as setup in main.cpp test file.

| Pin desc | HW SPI |
| --- | --- |
| GND Ground | GND |
| VCC | 3.3 VCC |
| SCL Clock | GPIO 18 |
| SDA Data in | GPIO 19 |
| RST Reset | GPIO 4 |
| DC Data or command | GPIO 3 |
| CS Chip select | GPIO 2 |
| BL Backlight | VCC thru resistor |

1. This is a 3.3V logic device do NOT connect the I/O logic lines to 5V logic device.
2. SW SPI pick any GPIO you like , HW SPI SCLK and SDA will be tied to spio interface.
3. Backlight on/off control is left to user.
4. If no Reset pin present: pass -1 as argument for Reset pin number in SetupGPIO()functions
5. To operate without CS pin: pass -1 as argument for CS pin number in SetupGPIO()function and ground the CS pin on device side.