Merge pull request #41 from r2axz/r2axz-re-enumerate-on-reset

Force USB re-enumeration on device reset
r2axz · Aug 24, 2021 · a1b6948 · a1b6948
2 parents 13f7657 + 7e30bd0
commit a1b6948
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diff --git a/Makefile b/Makefile
@@ -69,7 +69,7 @@ cppcheck: $(SRCS)
 
 .PHONY: flash
 flash: $(TARGET).hex
-	$(STFLASH) --format ihex write $<
+	$(STFLASH) --reset --format ihex write $<
 
 .PHONY: size
 size: $(TARGET).elf

diff --git a/usb_io.c b/usb_io.c
@@ -53,6 +53,16 @@ void usb_io_reset() {
 }
 
 void usb_io_init() {
+    /* Force USB re-enumeration */
+    RCC->APB2ENR |= RCC_APB2ENR_IOPAEN;
+    GPIOA->CRH &= ~GPIO_CRH_CNF12;
+    GPIOA->CRH |= GPIO_CRH_MODE12_1;
+    for (int i=0; i<0xFFFF; i++) {
+        __NOP();
+    }
+    GPIOA->CRH &= ~GPIO_CRH_MODE12;
+    GPIOA->CRH |= GPIO_CRH_CNF12_0;
+    /* Initialize USB */
     NVIC_DisableIRQ(USB_LP_CAN1_RX0_IRQn);
     if (SystemCoreClock != RCC_MAX_FREQUENCY) {
         RCC->CFGR |= RCC_CFGR_USBPRE;