Added 100us delay between USB power-down and system reset.

gkatev · Jul 5, 2020 · 044510b · 044510b
1 parent 791621b
commit 044510b
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Showing 2 changed files with 10 additions and 1 deletion.
diff --git a/core/usb_vcp.cpp b/core/usb_vcp.cpp
@@ -226,7 +226,6 @@ static enum usbd_request_return_codes vcp_control_request(
 		struct usb_setup_data *req)) {
 
 	switch (req->bRequest) {
-
 		case USB_CDC_REQ_SET_CONTROL_LINE_STATE:
 			g_usbd_is_connected = req->wValue & 1;
 
@@ -242,6 +241,11 @@ static enum usbd_request_return_codes vcp_control_request(
 			write_dfu_magicword();
 			kill_usb();
 
+			/* Wait ~100us (stm32f103). This appears to be
+			 * necessary in specific USB environments. */
+			for(uint i = 0; i < 1200; i++)
+				__asm__("nop");
+
 			scb_reset_system();
 
 			// Won't actually return

diff --git a/dfu-bootloader/usbdfu.c b/dfu-bootloader/usbdfu.c
@@ -187,6 +187,11 @@ static void usbdfu_getstatus_complete(usbd_device *usbd_dev, struct usb_setup_da
 		write_magic_word(MAGICWORD_LOAD_APP);
 		kill_usb();
 
+		/* Wait ~100us (stm32f103). This appears to be
+		 * necessary in specific USB environments. */
+		for(i = 0; i < 1200; i++)
+			__asm__("nop");
+
 		scb_reset_system();
 
 		return; /* Will never return. */