[UPD] README.md

Author: Plaenkler

README.md

@@ -17,19 +17,23 @@ Designed to support a wide range of ePaper displays from **WaveShare** and **Goo
 
  * MCU: ESP32-C3-WROOM-02-H4
  * Power supply: [Egg_LDO_1000](https://github.com/Plaenkler/Egg_LDO_1000)
- * Connectivity: I2C, UART over USB, UART
+ * Connectivity: SPI, UART/USB, 24-pin FPC ePaper connection
 
 ## ⚡ Circuit Diagram
 
-Coming soon...
+![gulu_circuit diagram](https://github.com/Plaenkler/Gulu_ESP32-C3_ePaper/assets/60503970/1ba6de68-8dc7-44b1-94b2-039d5cceef62)
 
-## Software capabilities
+## Power consumption
 
-Coming soon...
+The power consumption in deep sleep mode of the ESP32-C3 was measured using the [Power Profiler Kit II](https://www.nordicsemi.com/Products/Development-hardware/Power-Profiler-Kit-2) from Nordic Semiconductor.
+The example firmware in this project was used as a benchmark.
+A daughter board such as the [Egg_LDO_1000](https://github.com/Plaenkler/Egg_LDO_1000) was not used, and VOUT and GND of the kit were connected directly to the corresponding pads.
+During the measurement, a 7.5 inch black and white display ([WFT0583CZ61](https://www.good-display.com/product/396.html)) from [Good Display](https://www.good-display.com) was connected to the FPC port.
+The duration of the measurement in this case was one minute after the first cycle of the firmware, which resulted in an average current of **~35μA**.
+When the display is not connected, the current is approximately **~10μA** in deep sleep mode.
 
-## Board and connections
+![One_minute_deep_sleep](https://github.com/Plaenkler/Gulu_ESP32-C3_ePaper/assets/60503970/87c6e501-ffcb-41a7-be25-fa08fab55342)
 
-Coming soon...
 
 ## Arduino compatibility
 
@@ -52,16 +56,53 @@ static const uint8_t SCK   = 5; // EPD_SCK
 
 ## Firmware example
 
-Coming soon...
+### Display Definition and Image
 
-## Power consumption
+This section contains a header file with a definition for the display and a sample image.
+The display is initialized with the required pins specified for the GxEPD2 library.
+Additionally, a sample image is defined as an array of byte data stored in PROGMEM (program memory) of the microcontroller.
 
-The power consumption in deep sleep mode of the ESP32-C3 was measured using the [Power Profiler Kit II](https://www.nordicsemi.com/Products/Development-hardware/Power-Profiler-Kit-2) from Nordic Semiconductor.
-The example firmware in this project was used as a benchmark.
-A daughter board such as the [Egg_LDO_1000](https://github.com/Plaenkler/Egg_LDO_1000) was not used, and VOUT and GND of the kit were connected directly to the corresponding pads.
-During the measurement, a 7.5 inch black and white display ([WFT0583CZ61](https://www.good-display.com/product/396.html)) from [Good Display](https://www.good-display.com) was connected to the FPC port.
-The duration of the measurement in this case was one minute after the first cycle of the firmware, which resulted in an average current of **~35μA**.
-When the display is not connected, the current is approximately **~10μA** in deep sleep mode.
+```cpp
+#ifndef _750_T7_H_
+#define _750_T7_H_
 
-![One_minute_deep_sleep](https://github.com/Plaenkler/Gulu_ESP32-C3_ePaper/assets/60503970/87c6e501-ffcb-41a7-be25-fa08fab55342)
+#include <GxEPD2_BW.h>
+
+GxEPD2_BW<GxEPD2_750_T7, GxEPD2_750_T7::HEIGHT> display(
+  GxEPD2_750_T7(6, 7, 10, 3)
+);
+
+const unsigned char image[] PROGMEM = {
+    0x55, 0x55, 0x55, 0x6d, 0xb6, 0xdb, 0x6d, 0xb5, 0x6a, 0xbf, 0xf5, 0x22, ...
+```
+
+### Main Program
+
+The first section initializes the necessary components for the firmware.
+Firstly, the onboard LED (connected to pin 0) is configured as an output.
+Then, the display initialization is called.
 
+```cpp
+#include "750_T7.h"
+
+void setup() {
+  pinMode(0, OUTPUT);
+  display.init();
+}
+```
+
+In the main part of the program, the sample picture is displayed on the screen, after which the screen is switched to hibernation mode.
+Subsequently, the onboard LED is turned on for one second and then turned off.
+After that, a timer wakeup for the deep sleep mode is enabled, and the microcontroller is put into deep sleep.
+
+```cpp
+void loop() {
+  display.drawImage(image, 0, 0, 800, 480);
+  display.hibernate();
+  digitalWrite(0, 1);
+  delay(1e3);
+  digitalWrite(0, 0);
+  esp_sleep_enable_timer_wakeup(1e7);
+  esp_deep_sleep_start();
+}
+```