tweak to dual host info device cdc to make it easier to pass hil test

Author: hathach

examples/dual/host_info_to_device_cdc/src/main.c

@@ -108,6 +108,7 @@ static void usb_device_init(void) {
   tusb_init(BOARD_TUD_RHPORT, &dev_init);
   tud_cdc_configure_t cdc_cfg = TUD_CDC_CONFIGURE_DEFAULT();
   cdc_cfg.tx_persistent       = true;
+  cdc_cfg.tx_overwritabe_if_not_connected = false;
   tud_cdc_configure(&cdc_cfg);
   board_init_after_tusb();
 }
@@ -209,6 +210,13 @@ void tud_resume_cb(void) {
 }
 
 void cdc_task(void) {
+  if (!tud_cdc_connected()) {
+    // delay a bit otherwise we can outpace host's terminal. Linux will set LineState (DTR) then Line Coding.
+    // If we send data before Linux's terminal set Line Coding, it can be ignored --> missing data with hardware test loop
+    tusb_time_delay_ms_api(50);
+    return;
+  }
+
   for (uint8_t daddr = 1; daddr <= CFG_TUH_DEVICE_MAX; daddr++) {
     if (tuh_mounted(daddr)) {
       if (is_print[daddr]) {

examples/dual/host_info_to_device_cdc/src/tusb_config.h

@@ -112,7 +112,7 @@
 
 // CDC FIFO size of TX and RX
 #define CFG_TUD_CDC_RX_BUFSIZE   (TUD_OPT_HIGH_SPEED ? 512 : 64)
-#define CFG_TUD_CDC_TX_BUFSIZE   (TUD_OPT_HIGH_SPEED ? 512 : 64)
+#define CFG_TUD_CDC_TX_BUFSIZE   (TUD_OPT_HIGH_SPEED ? 512 : 256)
 
 // CDC Endpoint transfer buffer size, more is faster
 #define CFG_TUD_CDC_EP_BUFSIZE   (TUD_OPT_HIGH_SPEED ? 512 : 64)