1 files changed, 70 insertions, 0 deletions
diff --git a/fw/led.c b/fw/led.c
new file mode 100644
index 0000000..b9f1592
--- /dev/null
+++ b/fw/led.c
@@ -0,0 +1,70 @@
+/* Megumin LED display firmware
+ * Copyright (C) 2018 Sebastian Götte <code@jaseg.net>
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "global.h"
+#include "led.h"
+
+/* Status LED control */
+#define LED_STRETCHING_MS 50
+static volatile int error_led_timeout = 0;
+static volatile int comm_led_timeout = 0;
+static volatile int id_led_timeout = 0;
+
+volatile int led_state = 0;
+
+void trigger_error_led() {
+    error_led_timeout = LED_STRETCHING_MS;
+}
+
+void trigger_comm_led() {
+    comm_led_timeout = LED_STRETCHING_MS;
+}
+
+void trigger_id_led() {
+    id_led_timeout = LED_STRETCHING_MS;
+}
+
+void led_task() {
+    static int last_time = 0;
+    /* Crude LED logic. The comm, id and error LEDs each have a timeout counter
+     * that is reset to the LED_STRETCHING_MS constant on an event (either a
+     * frame received correctly or some uart, framing or protocol error). These
+     * timeout counters count down in milliseconds and the LEDs are set while
+     * they are non-zero. This means a train of several very brief events will
+     * make the LED lit permanently.
+     */
+    int time_now = sys_time; /* Latch sys_time here to avoid race conditions */
+    if (last_time != time_now) {
+        int diff = (time_now - last_time);
+
+        error_led_timeout -= diff;
+        if (error_led_timeout < 0)
+            error_led_timeout = 0;
+
+        comm_led_timeout -= diff;
+        if (comm_led_timeout < 0)
+            comm_led_timeout = 0;
+
+        id_led_timeout -= diff;
+        if (id_led_timeout < 0)
+            id_led_timeout = 0;
+
+        led_state = (led_state & ~7) | (!!id_led_timeout)<<2 | (!!error_led_timeout)<<1 | (!!comm_led_timeout)<<0;
+        last_time = time_now;
+    }
+}
+