Enable USB auto-reset in a hard fault.

Redirect thread-mode execution to a fail routine which throbs the LED to
indicate a hard fault. Because the fail routine runs in thread mode
with interrupts on, USB auto-reset should now work. Test by executing
some bogus instruction (e.g. *(volatile int*)0xf34fdaa = 0;) and check
that the auto-reset continues to work.

1 files changed, 31 insertions, 20 deletions

diff --git a/libmaple/util.c b/libmaple/util.c
index a747948..3325d2b 100644
--- a/libmaple/util.c
+++ b/libmaple/util.c
@@ -68,7 +68,7 @@ void _fail(const char* file, int line, const char* exp) {
     usart_putudec(ERROR_USART_NUM, line);
     usart_putc(ERROR_USART_NUM, '\n');
     usart_putc(ERROR_USART_NUM, '\r');
-    
+
     /* Turn on the error LED  */
     gpio_set_mode(ERROR_LED_PORT, ERROR_LED_PIN, GPIO_MODE_OUTPUT_PP);
 
@@ -77,24 +77,35 @@ void _fail(const char* file, int line, const char* exp) {
     nvic_irq_enable(NVIC_INT_USBLP);
 
     /* Error fade  */
-    while (1) {
-        if (CC == TOP_CNT)  {
-            slope = -1;
-        } else if (CC == 0) {
-            slope = 1;
-        }
-
-        if (i == TOP_CNT)  {
-            CC += slope;
-            i = 0;
-        }
-
-        if (i < CC) {
-            gpio_write_bit(ERROR_LED_PORT, ERROR_LED_PIN, 1);
-        } else {
-            gpio_write_bit(ERROR_LED_PORT, ERROR_LED_PIN, 0);
-        }
-        i++;
-    }
+    throb();
+}
+
+void throb(void) {
+   int32  slope   = 1;
+   uint32 CC      = 0x0000;
+   uint32 TOP_CNT = 0x0200;
+   uint32 i       = 0;
+
+   gpio_set_mode(ERROR_LED_PORT, ERROR_LED_PIN, GPIO_MODE_OUTPUT_PP);
+   /* Error fade  */
+   while (1) {
+      if (CC == TOP_CNT)  {
+         slope = -1;
+      } else if (CC == 0) {
+         slope = 1;
+      }
+
+      if (i == TOP_CNT)  {
+         CC += slope;
+         i = 0;
+      }
+
+      if (i < CC) {
+         gpio_write_bit(ERROR_LED_PORT, ERROR_LED_PIN, 1);
+      } else {
+         gpio_write_bit(ERROR_LED_PORT, ERROR_LED_PIN, 0);
+      }
+      i++;
+   }
 }