Added first documentation

servo_controller/COMMANDS.md

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+# USB Command Handler
+
+Implementation of command handler for this project.
+
+
+### ACK
+
+Every command returns either an ACK or NACK.
+
+### Commands
+```c
+typedef enum {
+	COMMAND_ACK,
+	COMMAND_NACK,
+	LED_TOGGLE,
+	LED_SET,
+	SERVO_SET,
+	SERVO_SET_ALL,
+	ADC_READ_RAW,
+	ADC_READ_RAW_ALL,
+	ADC_READ,
+	ADC_READ_ALL,
+	ADC_SET_READ,
+	DIGITAL_IN,
+	DIGITAL_LEG_OUT,
+	POWER_MONITOR_SET_READ,
+	POWER_MONITOR_READ,
+	SETTINGS_TEST_SAVE,
+	SETTINGS_TEST_READ,
+
+	MOVE_COMMAND_START,
+	// All the commands going to robot thread go here
+	TEST_COMMAND, // 16
+
+	MOVE_COMMAND_END
+
+} commands_e;
+```
+
+### Command Structure
+
+```c
+#define COMMAND_PREFIX 0x69
+#define COMMAND_ID 0x00
+#define COMMAND_DATA_SIZE 160
+#define COMMAND_HEADER_SIZE 13
+
+struct command_message_t {
+	uint8_t prefix;
+	uint8_t length;
+	uint8_t id;
+	uint8_t command;
+	int64_t tick;
+	uint8_t crc;
+	uint8_t data[COMMAND_DATA_SIZE];
+} __attribute__((packed));
+```
+
+### CRC Calculation Function
+
+```c
+uint8_t command_calculate_crc(struct command_message_t *msg) {
+	uint32_t sum = 0;
+	uint8_t crc = 0;
+
+	uint8_t *byte_ptr = (uint8_t *)msg;
+	int loop_length = (sizeof(struct command_message_t) - sizeof(msg->data) + msg->length);
+
+	for (int i = 0; i < loop_length; i++) {
+		if (i == (COMMAND_HEADER_SIZE - 1)) { continue; }
+		sum += byte_ptr[i];
+	}
+
+	crc = 0x100 - (sum & 0xff);
+
+	return crc;
+}
+```
+
+### Python test script (AI generated)
+
+**Command Usage:**
+
+```bash
+python3 scripts/send_cmd.py --help
+```
+
+This script sends/reads commands