Add st7789 lcd driver

Makefile

@@ -8,6 +8,7 @@ TARGET_FILE ?= $(APPLICATION).elf
 CC = $(CROSS_COMPILE)gcc
 CPP = $(CROSS_COMPILE)cpp
 OBJCOPY = $(CROSS_COMPILE)objcopy
+SIZE = $(CROSS_COMPILE)size
 
 SRC_DIR = src
 OBJ_DIR = obj/$(PLATFORM)
@@ -56,6 +57,7 @@ $(TARGET): $(OBJS) $(THIS_MAKEFILE)
 	@mkdir -p $(dir $@)
 	$(CC) $(CC_FLAGS) $(LD_FLAGS) $(OBJS) $(addprefix -l,$(LIBS)) -o $@
 	ln -sf $(shell pwd)/$@ $(shell pwd)/bin/firmware.elf
+	$(SIZE) -x $@
 
 $(TARGET_HEX): $(TARGET) $(THIS_MAKEFILE)
 	$(OBJCOPY) -O ihex $(TARGET) $(TARGET_HEX)

include/framebuffer.h

@@ -0,0 +1,12 @@
+#ifndef __INCLUDE_FRAMEBUFFER_H__
+#define __INCLUDE_FRAMEBUFFER_H__
+
+#include <stdint.h>
+
+void fb_draw_pixel(uint16_t *image, uint16_t x, uint16_t y, uint16_t color);
+void fb_draw_line(uint16_t *image, int16_t x0, int16_t y0, int16_t x1, int16_t y1, uint16_t color);
+
+void fb_load_image(uint16_t *dst, uint16_t *src, uint32_t length);
+void fb_set_image(uint16_t *dst, uint16_t value, uint32_t length);
+
+#endif

include/platform/nrf52/nrf52-dk.h

@@ -5,6 +5,7 @@
 
 #include "gpio.h"
 #include "spi.h"
+#include "st7789.h"
 
 // LED 1
 const struct gpio nrf_led_1 = {
@@ -50,17 +51,67 @@ const struct driver led_4 = {
     .dev = &nrf_led_4
 };
 
+// LCD
 // SPI 0
 const struct spi nrf_spi_0 = {
     .sck_pin = 2,
     .mosi_pin = 3,
-    .miso_pin = 0xff,
-    .ss_pin = 25
+    .miso_pin = 4
 };
 const struct driver spi_0 = {
     .name = "SPI0",
     .fp = &spi_fp,
     .dev = &nrf_spi_0
 };
+const struct gpio nrf_dc_pin = {
+    .pin = 18,
+    .dir = OUT
+};
+const struct driver dc_pin = {
+    .name = "DC",
+    .fp = &gpio_fp,
+    .dev = &nrf_dc_pin
+};
+const struct gpio nrf_bl_pin = {
+    .pin = 23,
+    .dir = OUT
+};
+const struct driver bl_pin = {
+    .name = "BACKLIGHT",
+    .fp = &gpio_fp,
+    .dev = &nrf_bl_pin
+};
+const struct gpio nrf_rst_pin = {
+    .pin = 26,
+    .dir = OUT
+};
+const struct driver rst_pin = {
+    .name = "RESET",
+    .fp = &gpio_fp,
+    .dev = &nrf_rst_pin
+};
+const struct gpio nrf_select_pin = {
+    .pin = 25,
+    .dir = OUT
+};
+const struct driver select_pin = {
+    .name = "SELECT",
+    .fp = &gpio_fp,
+    .dev = &nrf_select_pin
+};
+struct st7789 nrf_lcd = {
+    .spi = &spi_0,
+    .dc = &dc_pin,
+    .bl = &bl_pin,
+    .rst = &rst_pin,
+    .select = &select_pin,
+    .height = 240,
+    .width = 240,
+};
+const struct driver lcd = {
+    .name = "LCD",
+    .fp = &st7789_fp,
+    .dev = &nrf_lcd
+};
 
 #endif

include/spi.h

@@ -1,27 +1,21 @@
 #ifndef __NRF52_SPI_H__
 #define __NRF52_SPI_H__
 
-#include <stdint.h>
-
-#include "driver.h"
-
 int spi_open(const struct driver *drv);
 int spi_close(const struct driver *drv);
 
-int spi_read(const struct driver *drv, char *buffer, unsigned int len);
 int spi_write(const struct driver *drv, const char *buffer, unsigned int len);
 
 struct spi {
-    uint8_t sck_pin;
-    uint8_t mosi_pin;
-    uint8_t miso_pin;
-    uint8_t ss_pin;
+    unsigned int sck_pin;
+    unsigned int mosi_pin;
+    unsigned int miso_pin;
 };
 
 static const struct driver_fp spi_fp = {
     .open = spi_open,
     .close = spi_close,
-    .read = spi_read,
+    .read = NULL,
     .write = spi_write,
     .ioctl = NULL
 };

include/st7789.h

@@ -0,0 +1,30 @@
+#ifndef __ST7789_H__
+#define __ST7789_H__
+
+#include <stddef.h>
+
+#include "driver.h"
+
+int st7789_open(const struct driver *drv);
+int st7789_close(const struct driver *drv);
+int st7789_write(const struct driver *drv, const char *buffer, unsigned int len);
+
+struct st7789 {
+    const struct driver *spi;
+    const struct driver *dc;
+    const struct driver *bl;
+    const struct driver *rst;
+    const struct driver *select;
+    unsigned int height;
+    unsigned int width;
+};
+
+static const struct driver_fp st7789_fp = {
+    .open = st7789_open,
+    .close = st7789_close,
+    .read = NULL,
+    .write = st7789_write,
+    .ioctl = NULL,
+};
+
+#endif

src/application/spi/main.c

@@ -1,43 +1,3 @@
-/**
- * Copyright (c) 2015 - 2019, Nordic Semiconductor ASA
- *
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without modification,
- * are permitted provided that the following conditions are met:
- *
- * 1. Redistributions of source code must retain the above copyright notice, this
- *    list of conditions and the following disclaimer.
- *
- * 2. Redistributions in binary form, except as embedded into a Nordic
- *    Semiconductor ASA integrated circuit in a product or a software update for
- *    such product, must reproduce the above copyright notice, this list of
- *    conditions and the following disclaimer in the documentation and/or other
- *    materials provided with the distribution.
- *
- * 3. Neither the name of Nordic Semiconductor ASA nor the names of its
- *    contributors may be used to endorse or promote products derived from this
- *    software without specific prior written permission.
- *
- * 4. This software, with or without modification, must only be used with a
- *    Nordic Semiconductor ASA integrated circuit.
- *
- * 5. Any software provided in binary form under this license must not be reverse
- *    engineered, decompiled, modified and/or disassembled.
- *
- * THIS SOFTWARE IS PROVIDED BY NORDIC SEMICONDUCTOR ASA "AS IS" AND ANY EXPRESS
- * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
- * OF MERCHANTABILITY, NONINFRINGEMENT, AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL NORDIC SEMICONDUCTOR ASA OR CONTRIBUTORS BE
- * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
- * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
- * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
- * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-#include "nrf_drv_spi.h"
 #include "app_util_platform.h"
 #include "nrf_gpio.h"
 #include "nrf_delay.h"
@@ -48,63 +8,29 @@
 #include "nrf_log_ctrl.h"
 #include "nrf_log_default_backends.h"
 
-#define SPI_INSTANCE  0 /**< SPI instance index. */
-static const nrf_drv_spi_t spi = NRF_DRV_SPI_INSTANCE(SPI_INSTANCE);  /**< SPI instance. */
-static volatile bool spi_xfer_done;  /**< Flag used to indicate that SPI instance completed the transfer. */
+#include "board.h"
+#include "driver.h"
 
-#define TEST_STRING "Nordic"
-static uint8_t       m_tx_buf[] = TEST_STRING;           /**< TX buffer. */
-static uint8_t       m_rx_buf[sizeof(TEST_STRING) + 1];    /**< RX buffer. */
-static const uint8_t m_length = sizeof(m_tx_buf);        /**< Transfer length. */
-
-/**
- * @brief SPI user event handler.
- * @param event
- */
-void spi_event_handler(nrf_drv_spi_evt_t const * p_event,
-                       void *                    p_context)
-{
-    spi_xfer_done = true;
-    NRF_LOG_INFO("Transfer completed.");
-    if (m_rx_buf[0] != 0)
-    {
-        NRF_LOG_INFO(" Received:");
-        NRF_LOG_HEXDUMP_INFO(m_rx_buf, strlen((const char *)m_rx_buf));
-    }
-}
+const char buf[] = "Test";
 
 int main(void)
 {
-    bsp_board_init(BSP_INIT_LEDS);
-
+    unsigned int cnt = 0;
     APP_ERROR_CHECK(NRF_LOG_INIT(NULL));
     NRF_LOG_DEFAULT_BACKENDS_INIT();
 
-    nrf_drv_spi_config_t spi_config = NRF_DRV_SPI_DEFAULT_CONFIG;
-    spi_config.ss_pin   = SPI_SS_PIN;
-    spi_config.miso_pin = SPI_MISO_PIN;
-    spi_config.mosi_pin = SPI_MOSI_PIN;
-    spi_config.sck_pin  = SPI_SCK_PIN;
-    APP_ERROR_CHECK(nrf_drv_spi_init(&spi, &spi_config, spi_event_handler, NULL));
+    drv_open(&led_1);
+    drv_open(&spi_0);
 
     NRF_LOG_INFO("SPI example started.");
 
-    while (1)
-    {
-        // Reset rx buffer and transfer done flag
-        memset(m_rx_buf, 0, m_length);
-        spi_xfer_done = false;
-
-        APP_ERROR_CHECK(nrf_drv_spi_transfer(&spi, m_tx_buf, m_length, m_rx_buf, m_length));
-
-        while (!spi_xfer_done)
-        {
-            __WFE();
-        }
+    while(1) {
+        char c = (cnt++ % 2) + 0x30;
+        drv_write(&led_1, &c, 1);
+        drv_write(&spi_0, buf, sizeof(buf));
 
         NRF_LOG_FLUSH();
 
-        bsp_board_led_invert(BSP_BOARD_LED_0);
         nrf_delay_ms(200);
     }
 }

src/application/st7789_lcd/main.c

@@ -1,30 +1,33 @@
-#include <string.h>
-
 #include "app_util_platform.h"
-#include "board.h"
+#include "nrf_gpio.h"
+#include "nrf_delay.h"
+#include "boards.h"
 #include "app_error.h"
+#include <string.h>
+#include "nrf_log.h"
+#include "nrf_log_ctrl.h"
+#include "nrf_log_default_backends.h"
 
+#include "board.h"
 #include "driver.h"
-#include "delay.h"
 
-const char buffer[] = "Hello world!\r\n";
 int main(void)
 {
-    unsigned int i = 0;
+    unsigned int cnt = 0;
+    APP_ERROR_CHECK(NRF_LOG_INIT(NULL));
+    NRF_LOG_DEFAULT_BACKENDS_INIT();
+
     drv_open(&led_1);
-    drv_write(&led_1, "1", 1);
-    drv_open(&spi_0);
+    drv_open(&lcd);
 
-    // APP_ERROR_CHECK(NRF_LOG_INIT(NULL));
-    // NRF_LOG_DEFAULT_BACKENDS_INIT();
-
-    // NRF_LOG_INFO("SPI example started.");
+    NRF_LOG_INFO("SPI example started.");
 
     while(1) {
-        drv_write(&spi_0, buffer, sizeof(buffer));
-        // NRF_LOG_FLUSH();
-        char c = (i++ % 2) + 0x30;
+        char c = (cnt++ % 2) + 0x30;
         drv_write(&led_1, &c, 1);
-        delay_ms(200);
+
+        NRF_LOG_FLUSH();
+
+        nrf_delay_ms(200);
     }
 }

src/framebuffer.c

@@ -0,0 +1,76 @@
+#include <assert.h>
+#include <stddef.h>
+#include <stdlib.h>
+
+#include "framebuffer.h"
+
+void fb_draw_pixel(uint16_t *image, uint16_t x, uint16_t y, uint16_t color)
+{
+    assert(image != NULL);
+
+    image[x + 240 * y] = color;
+}
+
+#ifndef _swap_int16_t
+#define _swap_int16_t(a, b) { int16_t t = a; a = b; b = t; }
+#endif
+
+void fb_draw_line(uint16_t *image, int16_t x0, int16_t y0, int16_t x1, int16_t y1, uint16_t color)
+{
+    assert(image != NULL);
+
+    int16_t steep = abs(y1 - y0) > abs(x1 - x0);
+    if(steep) {
+        _swap_int16_t(x0, y0);
+        _swap_int16_t(x1, y1);
+    }
+    if(x0 > x1) {
+        _swap_int16_t(x0, x1);
+        _swap_int16_t(y0, y1);
+    }
+
+    int16_t dx, dy;
+    dx = x1 - x0;
+    dy = abs(y1 - y0);
+
+    int16_t err = dx / 2;
+    int16_t ystep;
+
+    if(y0 < y1) {
+        ystep = 1;
+    } else {
+        ystep = -1;
+    }
+
+    for(; x0 <= x1; x0++) {
+        if(steep) {
+            fb_draw_pixel(image, y0, x0, color);
+        } else {
+            fb_draw_pixel(image, x0, y0, color);
+        }
+        err -= dy;
+        if (err < 0) {
+            y0 += ystep;
+            err += dx;
+        }
+    }
+}
+
+void fb_load_image(uint16_t *dst, uint16_t *src, uint32_t length)
+{
+    assert(NULL != dst);
+    assert(NULL != src);
+
+    for(uint32_t i = 0; i < length; i++) {
+        dst[i] = src[i];
+    }
+}
+
+void fb_set_image(uint16_t *dst, uint16_t value, uint32_t length)
+{
+    assert(NULL != dst);
+
+    for (uint32_t i = 0; i < length; i++) {
+        dst[i] = value;
+    }
+}

src/platform/nrf52/spi.c

@@ -1,86 +1,61 @@
 #include <assert.h>
+#include <stddef.h>
 
-#include "nrf_drv_spi.h"
-#include "nrf_log.h"
-#include "nrf_log_ctrl.h"
-#include "nrf_log_default_backends.h"
+#include "nrf.h"
 
 #include "driver.h"
 #include "spi.h"
 
-#define SPI_INSTANCE    0
-static const nrf_drv_spi_t spi = NRF_DRV_SPI_INSTANCE(SPI_INSTANCE);
-static volatile bool spi_xfer_done;
-
-struct spi_object {
-    uint8_t *rx_buf;
-    uint8_t *tx_buf;
-    uint32_t rx_len;
-    uint32_t tx_len;
-};
-
-uint8_t rx_buffer[1];
-uint8_t tx_buffer[20];
-static struct spi_object spi_obj = {
-    .rx_buf = rx_buffer,
-    .tx_buf = tx_buffer,
-    .rx_len = sizeof(rx_buffer),
-    .tx_len = sizeof(tx_buffer)
-};
-
-void spi_event_handler(nrf_drv_spi_evt_t const * p_event, void * p_context)
-{
-    spi_xfer_done = true;
-    NRF_LOG_INFO("Transfer completed.");
-}
+static inline int spi_transfer(uint32_t t);
 
 int spi_open(const struct driver *drv)
 {
     assert(NULL != drv);
 
-    struct spi *this = (struct spi *)(drv->dev);
+    struct spi *this = (struct spi *)drv->dev;
 
-    nrf_drv_spi_config_t spi_config = NRF_DRV_SPI_DEFAULT_CONFIG;
-    spi_config.ss_pin = this->ss_pin;
-    spi_config.miso_pin = this->miso_pin;
-    spi_config.mosi_pin = this->mosi_pin;
-    spi_config.sck_pin  = this->sck_pin;
-    APP_ERROR_CHECK(nrf_drv_spi_init(&spi, &spi_config, spi_event_handler, NULL));
+    NRF_SPI0->ENABLE = 0;
+    NRF_SPI0->PSELSCK = this->sck_pin;
+    NRF_SPI0->PSELMOSI = this->mosi_pin;
+    NRF_SPI0->PSELMISO = this->miso_pin;
+    NRF_SPI0->FREQUENCY = SPI_FREQUENCY_FREQUENCY_M8;
+
+    NRF_SPI0->CONFIG = (0x03 << 1); //Sample on trailing edge of clock, shift serial data on leading edge, SCK polarity Active low
+    NRF_SPI0->EVENTS_READY = 0;
+    NRF_SPI0->ENABLE = (SPI_ENABLE_ENABLE_Enabled << SPI_ENABLE_ENABLE_Pos);
 
     return 0;
 }
 
 int spi_close(const struct driver *drv)
 {
-    assert(NULL != drv);
-
-    return 0;
-}
-
-int spi_read(const struct driver *drv, char *buffer, unsigned int len)
-{
-    assert((NULL != drv) && (NULL != buffer));
-
-    NRF_LOG_INFO("spi read not implemented yet.");
+    NRF_SPI0->ENABLE = 0;
 
     return 0;
 }
 
 int spi_write(const struct driver *drv, const char *buffer, unsigned int len)
 {
-    if(len > spi_obj.tx_len) {
-        NRF_LOG_ERROR("buffer too small");
-        return 0;
-    }
-    memcpy(spi_obj.tx_buf, buffer, len);
+    assert(NULL != buffer);
 
-    // Reset transfer done flag
-    spi_xfer_done = false;
+    //FIXME: missing CS handling
 
-    APP_ERROR_CHECK(nrf_drv_spi_transfer(&spi, spi_obj.tx_buf, spi_obj.tx_len, spi_obj.rx_buf, spi_obj.rx_len));
+    for(unsigned int i = 0; i < len; i++) {
+        spi_transfer(buffer[i]);
+    }
 
-    while(!spi_xfer_done) {
-        __WFE();
+    //FIXME: missing CS handling
+
+    return len;
 }
-    return (int)len;
+
+static inline int spi_transfer(uint32_t t)
+{
+    volatile uint32_t r;
+    NRF_SPI0->EVENTS_READY = 0;           // ready
+    NRF_SPI0->TXD = t;          // out
+    while(NRF_SPI0->EVENTS_READY == 0) {
+    }
+    r = NRF_SPI0->RXD;                    // in
+    return (int)r;
 }

src/st7789.c

@@ -0,0 +1,192 @@
+#include <assert.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <unistd.h>
+
+#include "delay.h"
+#include "st7789.h"
+
+static void send_cmd(const struct driver *drv, uint8_t cmd);
+static void send_data_8bit(const struct driver *drv, uint8_t data);
+
+static void lcd_init(const struct driver *drv);
+static void lcd_set_windows(const struct driver *drv, uint16_t x_start, uint16_t y_start, uint16_t x_end, uint16_t y_end);
+
+static void lcd_clear(const struct driver *drv, uint16_t Color)
+{
+    unsigned int i,j;
+    struct st7789 *this = (struct st7789*)(drv->dev);
+
+    lcd_set_windows(drv, 0, 0, 240, 240);
+    drv_write(this->dc, "1", 1);
+    for(i = 0; i < 240; i++) {
+        for(j = 0; j < 240; j++){
+            char c = (Color >> 8) & 0xff;
+            drv_write(this->spi, &c, 1);
+            c = Color & 0xff;
+            drv_write(this->spi, &c, 1);
+        }
+    }
+}
+
+int st7789_open(const struct driver *drv)
+{
+    assert(drv != NULL);
+    struct st7789 *this = (struct st7789*)(drv->dev);
+    drv_open(this->rst);
+    drv_write(this->rst, "1", 1);
+    drv_open(this->dc);
+    drv_write(this->dc, "1", 1);
+    drv_open(this->bl);
+    drv_write(this->bl, "1", 1);
+
+    drv_open(this->select);
+    drv_write(this->select, "0", 1);
+
+    drv_open(this->spi);
+    // hard reset
+    drv_write(this->rst, "0", 1);
+    delay_ms(100);
+    drv_write(this->rst, "1", 1);
+    delay_ms(100);
+
+    lcd_init(drv);
+
+    lcd_clear(drv, 0x0000);
+
+    return 0;
+}
+
+int st7789_close(const struct driver *drv)
+{
+    assert(drv != NULL);
+    struct st7789 *this = (struct st7789*)(drv->dev);
+    drv_close(this->rst);
+    drv_close(this->dc);
+    drv_close(this->bl);
+    drv_close(this->spi);
+    return 0;
+}
+
+int st7789_write(const struct driver *drv, const char *buffer, unsigned int len)
+{
+    assert(drv != NULL);
+    struct st7789 *this = (struct st7789*)(drv->dev);
+    uint16_t *image = (uint16_t *)buffer;
+    lcd_set_windows(drv, 0, 0, this->width, this->height);
+    drv_write(this->dc, "1", 1);
+    for (uint16_t i = 0; i < this->height; i++) {
+        drv_write(this->spi, (const char *)&image[i * this->width], len);
+    }
+    return len;
+}
+
+static void send_cmd(const struct driver *drv, uint8_t cmd)
+{
+    assert(drv != NULL);
+    struct st7789 *this = (struct st7789*)(drv->dev);
+    drv_write(this->dc, "0", 1);
+    drv_write(this->spi, (const char* )&cmd, 1);
+}
+
+static void send_data_8bit(const struct driver *drv, uint8_t data)
+{
+    assert(drv != NULL);
+    struct st7789 *this = (struct st7789*)(drv->dev);
+    drv_write(this->dc, "1", 1);
+    drv_write(this->spi, (const char* )&data, 1);
+}
+
+static void lcd_init(const struct driver *drv)
+{
+    send_cmd(drv, 0x36);
+    send_data_8bit(drv, 0x00);
+
+    send_cmd(drv, 0x3A);
+    send_data_8bit(drv, 0x05);
+
+    send_cmd(drv, 0xB2);
+    send_data_8bit(drv, 0x0C);
+    send_data_8bit(drv, 0x0C);
+    send_data_8bit(drv, 0x00);
+    send_data_8bit(drv, 0x33);
+    send_data_8bit(drv, 0x33);
+
+    send_cmd(drv, 0xB7);  //Gate Control
+    send_data_8bit(drv, 0x35);
+
+    send_cmd(drv, 0xBB);  //VCOM Setting
+    send_data_8bit(drv, 0x19);
+
+    send_cmd(drv, 0xC0); //LCM Control
+    send_data_8bit(drv, 0x2C);
+
+    send_cmd(drv, 0xC2);  //VDV and VRH Command Enable
+    send_data_8bit(drv, 0x01);
+    send_cmd(drv, 0xC3);  //VRH Set
+    send_data_8bit(drv, 0x12);
+    send_cmd(drv, 0xC4);  //VDV Set
+    send_data_8bit(drv, 0x20);
+
+    send_cmd(drv, 0xC6);  //Frame Rate Control in Normal Mode
+    send_data_8bit(drv, 0x0F);
+    
+    send_cmd(drv, 0xD0);  // Power Control 1
+    send_data_8bit(drv, 0xA4);
+    send_data_8bit(drv, 0xA1);
+
+    send_cmd(drv, 0xE0);  //Positive Voltage Gamma Control
+    send_data_8bit(drv, 0xD0);
+    send_data_8bit(drv, 0x04);
+    send_data_8bit(drv, 0x0D);
+    send_data_8bit(drv, 0x11);
+    send_data_8bit(drv, 0x13);
+    send_data_8bit(drv, 0x2B);
+    send_data_8bit(drv, 0x3F);
+    send_data_8bit(drv, 0x54);
+    send_data_8bit(drv, 0x4C);
+    send_data_8bit(drv, 0x18);
+    send_data_8bit(drv, 0x0D);
+    send_data_8bit(drv, 0x0B);
+    send_data_8bit(drv, 0x1F);
+    send_data_8bit(drv, 0x23);
+
+    send_cmd(drv, 0xE1);  //Negative Voltage Gamma Control
+    send_data_8bit(drv, 0xD0);
+    send_data_8bit(drv, 0x04);
+    send_data_8bit(drv, 0x0C);
+    send_data_8bit(drv, 0x11);
+    send_data_8bit(drv, 0x13);
+    send_data_8bit(drv, 0x2C);
+    send_data_8bit(drv, 0x3F);
+    send_data_8bit(drv, 0x44);
+    send_data_8bit(drv, 0x51);
+    send_data_8bit(drv, 0x2F);
+    send_data_8bit(drv, 0x1F);
+    send_data_8bit(drv, 0x1F);
+    send_data_8bit(drv, 0x20);
+    send_data_8bit(drv, 0x23);
+
+    send_cmd(drv, 0x21);  //Display Inversion On
+    send_cmd(drv, 0x11);  //Sleep Out
+    send_cmd(drv, 0x29);  //Display On
+}
+
+static void lcd_set_windows(const struct driver *drv, uint16_t x_start, uint16_t y_start, uint16_t x_end, uint16_t y_end)
+{
+    //set the X coordinates
+    send_cmd(drv, 0x2A);
+    send_data_8bit(drv, (x_start >> 8) & 0xFF);
+    send_data_8bit(drv, x_start & 0xFF);
+    send_data_8bit(drv, ((x_end  - 1) >> 8) & 0xFF);
+    send_data_8bit(drv, (x_end  - 1) & 0xFF);
+
+    //set the Y coordinates
+    send_cmd(drv, 0x2B);
+    send_data_8bit(drv, (y_start >> 8) & 0xFF);
+    send_data_8bit(drv, y_start & 0xFF);
+    send_data_8bit(drv, ((y_end  - 1) >> 8) & 0xFF);
+    send_data_8bit(drv, (y_end  - 1) & 0xFF);
+
+    send_cmd(drv, 0X2C);
+}