fix(core): 修复一些情况下板卡无法进入waiting for download模式

common/modules/mixly-modules/web/serial-transport.js

@@ -110,7 +110,11 @@ class Transport {
 
     async setRTS(state) {
         await this.serial.setRTS(state);
-        if (this.tracing) this.trace(`Set RTS = ${state}`);
+        await this.serial.setDTR(this.serial.getDTR());
+        if (this.tracing) {
+            this.trace(`Set RTS = ${state}`);
+            this.trace(`Set DTR = ${this.serial.getDTR()}`);
+        }
     }
 
     async setDTR(state) {

common/modules/mixly-modules/web/serialport.js

@@ -224,11 +224,23 @@ class WebSerialPort extends Serial {
     }
 
     async setDTR(dtr) {
-        return this.setDTRAndRTS(dtr, this.getRTS());
+        if (!this.isOpened()) {
+            return;
+        }
+        await this.#serialport_.setSignals({
+            dataTerminalReady: dtr
+        });
+        super.setDTR(dtr);
     }
 
     async setRTS(rts) {
-        return this.setDTRAndRTS(this.getDTR(), rts);
+        if (!this.isOpened()) {
+            return;
+        }
+        await this.#serialport_.setSignals({
+            requestToSend: rts
+        });
+        super.setRTS(rts);
     }
 
     getVID() {