diff --git a/peripheral/ymodem.c b/peripheral/ymodem.c
index 642f9bf..4b8f7c3 100644
--- a/peripheral/ymodem.c
+++ b/peripheral/ymodem.c
@@ -100,6 +100,34 @@ static enum rym_code _rym_read_code(struct rym_ctx *ctx, uint32_t timeout_ms)
     return RYM_CODE_NONE;
 }
 
+/* 带杂字节容忍的协议码等待: 超时窗口内逐字节扫描, 只认 accept 集合,
+ * 其余字节忽略并记 debug 日志.
+ * 场景: MCU 固件里 elog 与 ymodem 共用控制台串口, FIN 间隙的对端日志
+ * (ANSI 色码 0x1B 开头 / 文本行) 会插在协议码之前, "首字节即协议码"
+ * 的 _rym_read_code 会把它误判成协议错误 (实测 got 0x1B → -113) */
+static enum rym_code _rym_read_code_scan(struct rym_ctx *ctx, uint32_t timeout_ms,
+                                         const uint8_t *_pcAccept, size_t _nAccept)
+{
+    uint32_t start = Rd_GetTime();
+    while (Rd_GetTime() - start < timeout_ms)
+    {
+        size_t rsz = ctx->dev.read(ctx->dev.opaque, ctx->buf, 1);
+        if (rsz == 1)
+        {
+            uint8_t ucByte = *ctx->buf;
+            for (size_t k = 0; k < _nAccept; k++)
+            {
+                if (ucByte == _pcAccept[k])
+                    return (enum rym_code)ucByte;
+            }
+            log_d("ymodem: skip junk byte 0x%02X while waiting code", (unsigned)ucByte);
+            continue;
+        }
+        Rd_Delay(1);
+    }
+    return RYM_CODE_NONE;
+}
+
 static ssize_t _rym_read_data(struct rym_ctx *ctx, size_t len)
 {
     uint8_t *buf = ctx->buf + 1;
@@ -530,7 +558,13 @@ static int _rym_do_fin(struct rym_ctx *ctx)
         ctx->on_end(ctx, ctx->buf + 3, 128);
 
     _rym_putchar(ctx, RYM_CODE_NAK);
-    code = _rym_read_code(ctx, RYM_WAIT_PKG_MS);
+    /* 容忍杂字节扫描: 等发送端按双 EOT 约定补发的第二个 EOT.
+     * 发送端在收到 NAK 后可能正往同一条串口打日志 (共享控制台传输时),
+     * 首字节未必是 EOT, 不能用 _rym_read_code 直读 */
+    {
+        const uint8_t ucAccept[1] = { RYM_CODE_EOT };
+        code = _rym_read_code_scan(ctx, RYM_WAIT_PKG_MS, ucAccept, 1);
+    }
     if (code != RYM_CODE_EOT)
     {
         log_e("ymodem RX FIN phase: expected EOT, got 0x%02X (0x00=timeout)", (unsigned)code);
@@ -540,13 +574,20 @@ static int _rym_do_fin(struct rym_ctx *ctx)
     _rym_putchar(ctx, RYM_CODE_ACK);
     _rym_putchar(ctx, RYM_CODE_C);
 
-    code = _rym_read_code(ctx, RYM_WAIT_PKG_MS);
+    /* 等结束帧/下一文件包头, 同样容忍日志杂字节 */
+    {
+        const uint8_t ucAccept[2] = { RYM_CODE_SOH, RYM_CODE_STX };
+        code = _rym_read_code_scan(ctx, RYM_WAIT_PKG_MS, ucAccept, 2);
+    }
     if (code == RYM_CODE_SOH)
         data_sz = _RYM_SOH_PKG_SZ;
     else if (code == RYM_CODE_STX)
         data_sz = _RYM_STX_PKG_SZ;
     else
+    {
+        log_e("ymodem RX FIN phase: expected header, got 0x%02X (0x00=timeout)", (unsigned)code);
         return -RYM_ERR_CODE;
+    }
 
     i = _rym_read_data(ctx, data_sz - 1);
     if (i != (data_sz - 1))
@@ -583,7 +624,11 @@ static int _rym_do_send_fin(struct rym_ctx *ctx)
     data_sz = _RYM_SOH_PKG_SZ;
 
     /* EOT 阶段: 对端回 NAK 表示"请再发一次 EOT", 直接回 ACK 表示收到,
-     * 不回(超时)也重发; 三种情况都不能当失败退出 (有些接收端要两三次才确认) */
+     * 不回(超时)也重发; 三种情况都不能当失败退出 (有些接收端要两三次才确认)
+     * 【注意】NAK 是本工程接收端 (_rym_do_fin) 的标准首次应答, 属正常路径;
+     * 日志只能打 debug —— MCU 固件里 elog 与 ymodem 共用控制台串口,
+     * 在两次 EOT 之间往线上打 WARN 会污染协议流 (接收端会把 ANSI 色码
+     * 0x1B 当协议码, 误报 -113), 见 _rym_read_code_scan 注释 */
     for (retry = 0; ; retry++)
     {
         _rym_putchar(ctx, RYM_CODE_EOT);
@@ -605,7 +650,7 @@ static int _rym_do_send_fin(struct rym_ctx *ctx)
             return -RYM_ERR_ACK;
         }
 
-        log_w("ymodem TX fin: EOT %s -> resend (%u/%u)",
+        log_d("ymodem TX fin: EOT %s -> resend (%u/%u)",
               (getc_ack == RYM_CODE_NAK) ? "NAKed" : "no reply",
               (unsigned)(retry + 1), (unsigned)RYM_TX_RETRY_MAX);
     }