學長建議修改內容

src/unitdev04/esp32.py

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+from machine import UART
+import time
+import struct
+import gc
+
+# =========================================================
+# ESP32 / MicroPython：UAV 端 XBee <-> Flight Controller Bridge
+# Packet-size TDMA + DONE + SYSID / GCS address 自動學習版
+#
+# 本版已刪除「一般 DISC / 強制 DSCF」雙模式。
+# 現在只保留一種 discovery 封包，名稱統一叫 DISC。
+#
+# 重要：
+# - DISC 的功能等同於原本的 DSCF，也就是「強制 discovery」。
+# - UAV 收到 DISC 後，只要已知 MY_SYSID 與 DEST_64，就會重新回 HELO。
+# - 若收到 DISC 時 MY_SYSID 尚未學到，會設定 DISC_PENDING；
+#   之後一旦從飛控 MAVLink 學到 SYSID，就自動補送 HELO。
+#
+# 封包格式：
+# GCS -> UAV:
+#   DISC
+#   POLL + target_sysid(1) + grant_bytes(2)
+#   COMM / RTK broadcast downlink bytes
+#
+# UAV -> GCS:
+#   HELO + sysid(1)
+#   DONE + sysid(1) + sent_len(2) + remain_len(2)
+#
+# 注意：
+# - HELO 不帶 remain。
+# - DONE 保留 remain。
+# - MY_SYSID 不寫死，由飛控 MAVLink 自動學。
+# - DEST_64 不寫死，由 DISC 的 XBee 0x90 src64 自動學。
+# - POLL 只負責 TDMA 授權；COMM / RTK 直接 forward。
+# =========================================================
+
+
+# ================= 設定區 =================
+FC_BAUDRATE = 115200
+XB_BAUDRATE = 115200
+
+DEST_64 = None
+MY_SYSID = None
+
+SYSID_LEARN_CONFIRM_COUNT = 3
+_sysid_candidate = None
+_sysid_candidate_count = 0
+
+# 若收到 DISC 時還沒學到 MY_SYSID，就先記住。
+# 等之後從 FC MAVLink 學到 MY_SYSID 後，自動補送 HELO。
+DISC_PENDING = False
+
+XBEE_MAX_PAYLOAD = 100
+
+# Discovery：只保留 DISC；功能等同原本 DSCF，收到後強制回 HELO。
+DISC_MAGIC = b'DISC'
+
+# UAV -> GCS hello：
+# HELO + sysid(1)
+HELLO_MAGIC = b'HELO'
+
+HELLO_MIN_INTERVAL_MS = 1000
+_last_hello_ms = 0
+
+# 保留此變數只作狀態記錄；本版 DISC 會 force=True，所以不會被 HELLO_SENT 擋掉。
+HELLO_SENT = False
+
+POLL_MAGIC = b'POLL'
+DEFAULT_GRANT_BYTES = 600
+
+DONE_MAGIC = b'DONE'
+
+MAX_BUF_SIZE = 6144
+READ_FC_BYTES = 250
+
+FC_UART_ID = 1
+FC_TX_PIN = 32
+FC_RX_PIN = 33
+
+XB_UART_ID = 2
+XB_TX_PIN = 25
+XB_RX_PIN = 26
+# =========================================
+
+
+uart_fc = UART(FC_UART_ID, baudrate=FC_BAUDRATE, tx=FC_TX_PIN, rx=FC_RX_PIN, rxbuf=4096)
+uart_xb = UART(XB_UART_ID, baudrate=XB_BAUDRATE, tx=XB_TX_PIN, rx=XB_RX_PIN, rxbuf=4096)
+
+tx_buf = bytearray()  # FC -> GCS 等待 TDMA poll 的 MAVLink stream
+rx_buf = bytearray()  # XBee API frame parser buffer
+
+
+# =========================================================
+# 基本工具函式
+# =========================================================
+
+def get_checksum(data):
+    return 0xFF - (sum(data) & 0xFF)
+
+
+def is_valid_addr64(addr):
+    if addr is None:
+        return False
+    if len(addr) != 8:
+        return False
+    if addr == b'\x00\x00\x00\x00\x00\x00\x00\x00':
+        return False
+    return True
+
+
+def learn_dest64_from_src64(src64):
+    """
+    UAV 收到 GCS 的 XBee 0x90 frame 時，
+    0x90 裡面的 src64 就是 GCS / coordinator XBee 的 64-bit address。
+    """
+    global DEST_64
+    global HELLO_SENT
+    global DISC_PENDING
+
+    if not is_valid_addr64(src64):
+        return False
+
+    src64 = bytes(src64)
+
+    if DEST_64 is None:
+        DEST_64 = src64
+        HELLO_SENT = False
+        return True
+
+    if DEST_64 != src64:
+        DEST_64 = src64
+        HELLO_SENT = False
+        DISC_PENDING = False
+        return True
+
+    return False
+
+
+def build_api_tx_frame(payload):
+    """
+    建立 XBee API frame type 0x10，把 payload 送到 DEST_64。
+    若 DEST_64 尚未學到，回傳 None。
+    """
+    if DEST_64 is None:
+        return None
+
+    frame_content = bytearray()
+    frame_content.append(0x10)
+    frame_content.append(0x00)
+    frame_content.extend(DEST_64)
+    frame_content.extend(b'\xFF\xFE')
+    frame_content.append(0x00)
+    frame_content.append(0x00)
+    frame_content.extend(payload)
+
+    length = len(frame_content)
+
+    packet = bytearray()
+    packet.append(0x7E)
+    packet.append((length >> 8) & 0xFF)
+    packet.append(length & 0xFF)
+    packet.extend(frame_content)
+    packet.append(get_checksum(frame_content))
+
+    return packet
+
+
+def send_to_xbee_chunked(payload):
+    """
+    把 payload 依 XBEE_MAX_PAYLOAD 切成多個 XBee API TX frame 送出。
+    """
+    if DEST_64 is None:
+        return False
+
+    total_len = len(payload)
+    sent_len = 0
+
+    while sent_len < total_len:
+        end_len = min(sent_len + XBEE_MAX_PAYLOAD, total_len)
+        chunk = payload[sent_len:end_len]
+        sent_len = end_len
+
+        pkt = build_api_tx_frame(chunk)
+        if pkt is None:
+            return False
+
+        uart_xb.write(pkt)
+        time.sleep_ms(1)
+
+    return True
+
+
+# =========================================================
+# HELO / DONE 回報
+# =========================================================
+
+def send_hello_report(force=False):
+    """
+    UAV 回報自己存在：
+        HELO + MY_SYSID
+
+    本版 DISC 預設以 force=True 呼叫，因此每次收到 DISC 都會重新回 HELO。
+    """
+    global _last_hello_ms
+    global HELLO_SENT
+
+    if MY_SYSID is None:
+        return False
+    if DEST_64 is None:
+        return False
+
+    if HELLO_SENT and not force:
+        return False
+
+    now = time.ticks_ms()
+    if not force:
+        if time.ticks_diff(now, _last_hello_ms) < HELLO_MIN_INTERVAL_MS:
+            return False
+
+    payload = HELLO_MAGIC + struct.pack('>B', MY_SYSID)
+    pkt = build_api_tx_frame(payload)
+    if pkt is None:
+        return False
+
+    uart_xb.write(pkt)
+    _last_hello_ms = now
+    HELLO_SENT = True
+
+    time.sleep_ms(1)
+    return True
+
+
+def try_send_pending_hello():
+    """
+    若先收到 DISC、後學到 MY_SYSID，這裡會自動補送 HELO。
+    """
+    global DISC_PENDING
+
+    if DISC_PENDING and MY_SYSID is not None and DEST_64 is not None:
+        delay_ms = 20 + (((MY_SYSID * 37) + (time.ticks_ms() & 0xFF)) % 180)
+        time.sleep_ms(delay_ms)
+
+        if send_hello_report(force=True):
+            DISC_PENDING = False
+
+
+def send_done_report(sent_len, remain_len):
+    """
+    DONE payload:
+        b'DONE' + sysid(1) + sent_len(2) + remain_len(2)
+    """
+    if MY_SYSID is None:
+        return False
+    if DEST_64 is None:
+        return False
+
+    if sent_len > 65535:
+        sent_len = 65535
+    if remain_len > 65535:
+        remain_len = 65535
+
+    payload = DONE_MAGIC + struct.pack('>BHH', MY_SYSID, sent_len, remain_len)
+    pkt = build_api_tx_frame(payload)
+    if pkt is None:
+        return False
+
+    uart_xb.write(pkt)
+    time.sleep_ms(1)
+    return True
+
+
+# =========================================================
+# MAVLink frame 解析與 MY_SYSID 自動學習
+# =========================================================
+
+def find_first_mavlink_magic(buf):
+    pos_fe = buf.find(b'\xFE')
+    pos_fd = buf.find(b'\xFD')
+
+    if pos_fe == -1:
+        return pos_fd
+    if pos_fd == -1:
+        return pos_fe
+    return pos_fe if pos_fe < pos_fd else pos_fd
+
+
+def mavlink_frame_length(buf, start_idx):
+    if start_idx >= len(buf):
+        return None
+
+    magic = buf[start_idx]
+
+    if magic == 0xFE:
+        if len(buf) - start_idx < 2:
+            return None
+        payload_len = buf[start_idx + 1]
+        total_len = payload_len + 8
+        if len(buf) - start_idx < total_len:
+            return None
+        return total_len
+
+    if magic == 0xFD:
+        if len(buf) - start_idx < 3:
+            return None
+        payload_len = buf[start_idx + 1]
+        incompat_flags = buf[start_idx + 2]
+        signed = (incompat_flags & 0x01) != 0
+        total_len = payload_len + 12 + (13 if signed else 0)
+        if len(buf) - start_idx < total_len:
+            return None
+        return total_len
+
+    return None
+
+
+def get_mavlink_sysid(buf, start_idx):
+    if start_idx >= len(buf):
+        return None
+
+    magic = buf[start_idx]
+
+    if magic == 0xFE:
+        if len(buf) - start_idx >= 6:
+            return buf[start_idx + 3]
+
+    if magic == 0xFD:
+        if len(buf) - start_idx >= 10:
+            return buf[start_idx + 5]
+
+    return None
+
+
+def learn_my_sysid_from_tx_buf():
+    """
+    從 FC -> ESP32 的 tx_buf 中找完整 MAVLink frame，
+    並自動學習飛控的 MAVLink SYSID。
+
+    若更改飛控 SYSID，建議重新上電 ESP32，讓 MY_SYSID 重新學習。
+    """
+    global MY_SYSID
+    global _sysid_candidate
+    global _sysid_candidate_count
+    global HELLO_SENT
+    global tx_buf
+
+    # 已經學到 SYSID 後，不再掃 tx_buf，減少 ESP32 運算量
+    if MY_SYSID is not None:
+        return
+
+    if len(tx_buf) == 0:
+        return
+
+    idx = 0
+    checked = 0
+
+    while idx < len(tx_buf) and checked < 8:
+        sub = tx_buf[idx:]
+        rel_start = find_first_mavlink_magic(sub)
+        if rel_start == -1:
+            return
+
+        start = idx + rel_start
+        frame_len = mavlink_frame_length(tx_buf, start)
+        if frame_len is None:
+            return
+
+        sysid = get_mavlink_sysid(tx_buf, start)
+
+        if sysid is not None and sysid > 0:
+            if _sysid_candidate == sysid:
+                _sysid_candidate_count += 1
+            else:
+                _sysid_candidate = sysid
+                _sysid_candidate_count = 1
+
+            if _sysid_candidate_count >= SYSID_LEARN_CONFIRM_COUNT:
+                MY_SYSID = _sysid_candidate
+                HELLO_SENT = False
+                return
+
+        idx = start + frame_len
+        checked += 1
+
+
+# =========================================================
+# tx_buf MAVLink frame 取出與裁切
+# =========================================================
+
+def pop_mavlink_frames_by_quota(quota_bytes):
+    global tx_buf
+
+    if quota_bytes <= 0 or len(tx_buf) == 0:
+        return b''
+
+    start = find_first_mavlink_magic(tx_buf)
+    if start == -1:
+        tx_buf = bytearray()
+        return b''
+
+    if start > 0:
+        tx_buf = tx_buf[start:]
+
+    out = bytearray()
+
+    while len(tx_buf) > 0:
+        if tx_buf[0] not in (0xFE, 0xFD):
+            start = find_first_mavlink_magic(tx_buf)
+            if start == -1:
+                tx_buf = bytearray()
+                break
+            tx_buf = tx_buf[start:]
+
+        frame_len = mavlink_frame_length(tx_buf, 0)
+        if frame_len is None:
+            break
+
+        if len(out) > 0 and (len(out) + frame_len) > quota_bytes:
+            break
+
+        if len(out) == 0 and frame_len > quota_bytes:
+            out.extend(tx_buf[:frame_len])
+            tx_buf = tx_buf[frame_len:]
+            break
+
+        out.extend(tx_buf[:frame_len])
+        tx_buf = tx_buf[frame_len:]
+
+        if len(out) >= quota_bytes:
+            break
+
+    return bytes(out)
+
+
+def trim_tx_buffer_if_needed():
+    global tx_buf
+
+    if len(tx_buf) <= MAX_BUF_SIZE:
+        return
+
+    target_size = MAX_BUF_SIZE // 2
+
+    while len(tx_buf) > target_size:
+        start = find_first_mavlink_magic(tx_buf)
+        if start == -1:
+            tx_buf = bytearray()
+            return
+
+        if start > 0:
+            tx_buf = tx_buf[start:]
+            continue
+
+        frame_len = mavlink_frame_length(tx_buf, 0)
+        if frame_len is None:
+            if len(tx_buf) > target_size:
+                tx_buf = tx_buf[-target_size:]
+            return
+
+        tx_buf = tx_buf[frame_len:]
+
+
+def flush_tx_buffer(grant_bytes):
+    global tx_buf
+
+    # DEST_64 未學到時不能送資料，保留防護避免先 pop tx_buf 造成資料遺失
+    if DEST_64 is None:
+        return
+
+    if grant_bytes <= 0:
+        send_done_report(0, len(tx_buf))
+        return
+
+    data_to_send = pop_mavlink_frames_by_quota(grant_bytes)
+    sent_len = len(data_to_send)
+
+    if sent_len > 0:
+        send_to_xbee_chunked(data_to_send)
+
+    send_done_report(sent_len, len(tx_buf))
+
+
+# =========================================================
+# GCS control payload 解析
+# =========================================================
+
+def parse_poll_payload(real_data):
+    if not real_data.startswith(POLL_MAGIC):
+        return None, None
+
+    if len(real_data) == 5:
+        return real_data[4], DEFAULT_GRANT_BYTES
+
+    if len(real_data) == 7:
+        target_sysid = real_data[4]
+        grant_bytes = (real_data[5] << 8) | real_data[6]
+        return target_sysid, grant_bytes
+
+    return None, None
+
+
+def is_discovery_payload(real_data):
+    return real_data.startswith(DISC_MAGIC)
+
+
+# =========================================================
+# XBee API RX parser
+# =========================================================
+
+def process_xbee_buffer():
+    global rx_buf
+    global DISC_PENDING
+
+    while True:
+        start_pos = rx_buf.find(b'\x7E')
+        if start_pos == -1:
+            rx_buf = bytearray()
+            return
+
+        if start_pos > 0:
+            rx_buf = rx_buf[start_pos:]
+
+        if len(rx_buf) < 3:
+            return
+
+        pkt_len = (rx_buf[1] << 8) | rx_buf[2]
+        total_len = pkt_len + 4
+
+        if pkt_len > 300:
+            rx_buf = rx_buf[1:]
+            continue
+
+        if len(rx_buf) < total_len:
+            return
+
+        packet = rx_buf[3:3 + pkt_len]
+        checksum_recv = rx_buf[3 + pkt_len]
+
+        if get_checksum(packet) == checksum_recv:
+            if len(packet) > 0 and packet[0] == 0x90:
+                # XBee Receive Packet 0x90:
+                # packet = 90 | src64(8) | src16(2) | options(1) | RF data
+                if len(packet) >= 12:
+                    src64 = bytes(packet[1:9])
+                    real_data = packet[12:]
+
+                    # -------------------------------------------------
+                    # DISC：本版唯一 discovery 封包。
+                    # 功能等同原本 DSCF：收到後強制回 HELO。
+                    # -------------------------------------------------
+                    if is_discovery_payload(real_data):
+                        learn_dest64_from_src64(src64)
+                        learn_my_sysid_from_tx_buf()
+
+                        if MY_SYSID is not None and DEST_64 is not None:
+                            delay_ms = 20 + (((MY_SYSID * 37) + (time.ticks_ms() & 0xFF)) % 180)
+                            time.sleep_ms(delay_ms)
+                            send_hello_report(force=True)
+                            DISC_PENDING = False
+                        else:
+                            DISC_PENDING = True
+
+                    else:
+                        # -------------------------------------------------
+                        # 判斷是不是 POLL
+                        # -------------------------------------------------
+                        target_sysid, grant_bytes = parse_poll_payload(real_data)
+
+                        if target_sysid is not None:
+                            # POLL 只負責 TDMA 授權；DISC 已負責 GCS address / SYSID 學習
+                            if MY_SYSID is not None and target_sysid == MY_SYSID:
+                                flush_tx_buffer(grant_bytes)
+
+                        else:
+                            # COMM / RTK / 一般 GCS broadcast 下行資料
+                            # DISC 與 POLL 已經在前面處理掉，剩下資料直接轉給 FC / RTK module
+                            uart_fc.write(real_data)
+
+            rx_buf = rx_buf[total_len:]
+
+        else:
+            rx_buf = rx_buf[1:]
+
+
+# =========================================================
+# 初始清理
+# =========================================================
+
+try:
+    gc.collect()
+except Exception:
+    pass
+
+
+# =========================================================
+# 主迴圈
+# =========================================================
+
+while True:
+    try:
+        # -------------------------------------------------
+        # FC -> ESP32 tx buffer
+        # -------------------------------------------------
+        if uart_fc.any():
+            data = uart_fc.read(READ_FC_BYTES)
+            if data:
+                tx_buf.extend(data)
+
+                learn_my_sysid_from_tx_buf()
+                try_send_pending_hello()
+                trim_tx_buffer_if_needed()
+
+        # -------------------------------------------------
+        # XBee -> ESP32
+        # -------------------------------------------------
+        if uart_xb.any():
+            chunk = uart_xb.read()
+            if chunk:
+                rx_buf.extend(chunk)
+
+            process_xbee_buffer()
+
+        time.sleep_ms(1)
+
+    except MemoryError:
+        tx_buf = bytearray()
+        rx_buf = bytearray()
+
+        try:
+            gc.collect()
+        except Exception:
+            pass
+
+        time.sleep_ms(10)
+
+    except Exception:
+        time.sleep_ms(2)