1 files changed, 102 insertions, 0 deletions

diff --git a/protocol/pjrc/usb_debug.c b/protocol/pjrc/usb_debug.c
new file mode 100644
index 000000000..c1e6f6544
--- /dev/null
+++ b/protocol/pjrc/usb_debug.c
@@ -0,0 +1,102 @@
+/* USB Keyboard Plus Debug Channel Example for Teensy USB Development Board
+ * http://www.pjrc.com/teensy/usb_keyboard.html
+ * Copyright (c) 2009 PJRC.COM, LLC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <avr/interrupt.h>
+#include "sendchar.h"
+#include "usb_debug.h"
+
+
+// the time remaining before we transmit any partially full
+// packet, or send a zero length packet.
+volatile uint8_t debug_flush_timer=0;
+
+
+int8_t sendchar(uint8_t c)
+{
+        static uint8_t previous_timeout=0;
+        uint8_t timeout, intr_state;
+
+        // if we're not online (enumerated and configured), error
+        if (!usb_configured()) return -1;
+        // interrupts are disabled so these functions can be
+        // used from the main program or interrupt context,
+        // even both in the same program!
+        intr_state = SREG;
+        cli();
+        UENUM = DEBUG_TX_ENDPOINT;
+        // if we gave up due to timeout before, don't wait again
+        if (previous_timeout) {
+                if (!(UEINTX & (1<<RWAL))) {
+                        SREG = intr_state;
+                        return -1;
+                }
+                previous_timeout = 0;
+        }
+        // wait for the FIFO to be ready to accept data
+        timeout = UDFNUML + 4;
+        while (1) {
+                // are we ready to transmit?
+                if (UEINTX & (1<<RWAL)) break;
+                SREG = intr_state;
+                // have we waited too long?
+                if (UDFNUML == timeout) {
+                        previous_timeout = 1;
+                        return -1;
+                }
+                // has the USB gone offline?
+                if (!usb_configured()) return -1;
+                // get ready to try checking again
+                intr_state = SREG;
+                cli();
+                UENUM = DEBUG_TX_ENDPOINT;
+        }
+        // actually write the byte into the FIFO
+        UEDATX = c;
+        // if this completed a packet, transmit it now!
+        if (!(UEINTX & (1<<RWAL))) {
+                UEINTX = 0x3A;
+                debug_flush_timer = 0;
+        } else {
+                debug_flush_timer = 2;
+        }
+        SREG = intr_state;
+        return 0;
+}
+
+// immediately transmit any buffered output.
+void usb_debug_flush_output(void)
+{
+        uint8_t intr_state;
+
+        intr_state = SREG;
+        cli();
+        if (debug_flush_timer) {
+                UENUM = DEBUG_TX_ENDPOINT;
+                while ((UEINTX & (1<<RWAL))) {
+                        UEDATX = 0;
+                }
+                UEINTX = 0x3A;
+                debug_flush_timer = 0;
+        }
+        SREG = intr_state;
+}