diff --git a/sw/controller/src/app.c b/sw/controller/src/app.c
index a0cf63f..2568874 100644
--- a/sw/controller/src/app.c
+++ b/sw/controller/src/app.c
@@ -1,3 +1,4 @@
+#include <stdbool.h>
 #include "button.h"
 #include "cfg.h"
 #include "cic.h"
@@ -6,6 +7,7 @@
 #include "fpga.h"
 #include "hw.h"
 #include "isv.h"
+#include "led.h"
 #include "rtc.h"
 #include "sd.h"
 #include "timer.h"
@@ -28,17 +30,19 @@ void app (void) {
     dd_init();
     flashram_init();
     isv_init();
+    led_init();
     sd_init();
     usb_init();
     writeback_init();
 
-    while (1) {
+    while (true) {
         button_process();
         cfg_process();
         cic_process();
         dd_process();
         flashram_process();
         isv_process();
+        led_process();
         rtc_process();
         sd_process();
         usb_process();
diff --git a/sw/controller/src/cfg.c b/sw/controller/src/cfg.c
index a2509b7..4a6e805 100644
--- a/sw/controller/src/cfg.c
+++ b/sw/controller/src/cfg.c
@@ -5,6 +5,7 @@
 #include "flash.h"
 #include "fpga.h"
 #include "isv.h"
+#include "led.h"
 #include "rtc.h"
 #include "sd.h"
 #include "usb.h"
@@ -560,12 +561,16 @@ void cfg_process (void) {
                     case SD_CARD_OP_DEINIT:
                         sd_card_deinit();
                         break;
-                    case SD_CARD_OP_INIT:
-                        if (sd_card_init()) {
+                    case SD_CARD_OP_INIT: {
+                        led_activity_on();
+                        bool error = sd_card_init();
+                        led_activity_off();
+                        if (error) {
                             cfg_set_error(CFG_ERROR_SD_CARD);
                             return;
                         }
                         break;
+                    }
                     case SD_CARD_OP_GET_STATUS:
                         args[1] = sd_card_get_status();
                         break;
@@ -601,7 +606,7 @@ void cfg_process (void) {
                 p.sd_card_sector = args[0];
                 break;
 
-            case 's':
+            case 's': {
                 if (args[1] >= 0x800000) {
                     cfg_set_error(CFG_ERROR_BAD_ARGUMENT);
                     return;
@@ -610,14 +615,18 @@ void cfg_process (void) {
                     cfg_set_error(CFG_ERROR_BAD_ADDRESS);
                     return;
                 }
-                if (sd_read_sectors(args[0], p.sd_card_sector, args[1])) {
+                led_activity_on();
+                bool error = sd_read_sectors(args[0], p.sd_card_sector, args[1]);
+                led_activity_off();
+                if (error) {
                     cfg_set_error(CFG_ERROR_SD_CARD);
                     return;
                 }
                 p.sd_card_sector += args[1];
                 break;
+            }
 
-            case 'S':
+            case 'S': {
                 if (args[1] >= 0x800000) {
                     cfg_set_error(CFG_ERROR_BAD_ARGUMENT);
                     return;
@@ -626,12 +635,16 @@ void cfg_process (void) {
                     cfg_set_error(CFG_ERROR_BAD_ADDRESS);
                     return;
                 }
-                if (sd_write_sectors(args[0], p.sd_card_sector, args[1])) {
+                led_activity_on();
+                bool error = sd_write_sectors(args[0], p.sd_card_sector, args[1]);
+                led_activity_off();
+                if (error) {
                     cfg_set_error(CFG_ERROR_SD_CARD);
                     return;
                 }
                 p.sd_card_sector += args[1];
                 break;
+            }
 
             case 'D':
                 if (cfg_translate_address(&args[0], args[1], (SDRAM | BRAM))) {
diff --git a/sw/controller/src/dd.c b/sw/controller/src/dd.c
index d28babb..cafd82e 100644
--- a/sw/controller/src/dd.c
+++ b/sw/controller/src/dd.c
@@ -263,7 +263,7 @@ void dd_set_disk_mapping (uint32_t address, uint32_t length) {
 }
 
 void dd_handle_button (void) {
-    led_blink_act();
+    led_activity_pulse();
     if (dd_get_disk_state() == DD_DISK_STATE_EJECTED) {
         dd_set_disk_state(DD_DISK_STATE_INSERTED);
     } else {
diff --git a/sw/controller/src/led.c b/sw/controller/src/led.c
index ef4996f..076ec52 100644
--- a/sw/controller/src/led.c
+++ b/sw/controller/src/led.c
@@ -1,147 +1,147 @@
 #include <stdbool.h>
-// #include "hw.h"
+#include "hw.h"
 #include "led.h"
-// #include "rtc.h"
-// #include "timer.h"
+#include "rtc.h"
+#include "timer.h"
 
 
-// #define LED_MS_PER_TICK         (10)
-// #define LED_ERROR_TICKS_PERIOD  (50)
-// #define LED_ERROR_TICKS_ON      (25)
-// #define LED_ACT_TICKS_PERIOD    (15)
-// #define LED_ACT_TICKS_ON        (6)
+#define LED_REFRESH_PERIOD_MS   (50)
+
+#define LED_PULSE_LENGTH_MS     (500)
+
+#define ERROR_BLINK_PERIOD_MS   (100)
+#define ERROR_TOTAL_PERIOD_MS   (1000)
+
+#define CIC_ERROR_BLINKS        (1)
+#define RTC_ERROR_BLINKS        (2)
 
 
-// static bool error_mode = false;
-// static uint32_t error_timer = 0;
-// static volatile bool cic_error = false;
-// static volatile bool rtc_error = false;
+static bool activity_pulse = false;
+static int activity_pulse_timer = 0;
 
-// static uint32_t act_timer = 0;
-// static uint32_t current_act_counter = 0;
-// static volatile uint32_t next_act_counter = 0;
+static bool cic_error = false;
+static bool rtc_error = false;
+static bool error_active = false;
+static int error_timer = 0;
 
 
-// static void led_task_resume (void) {
-//     task_set_ready(TASK_ID_LED);
-// }
+void led_activity_on (void) {
+    rtc_settings_t *settings = rtc_get_settings();
+    if (!activity_pulse && !error_active && settings->led_enabled) {
+        hw_gpio_set(GPIO_ID_LED);
+    }
+}
 
-// static void led_set_state (bool state, bool force) {
-//     rtc_settings_t *settings = rtc_get_settings();
-//     if (settings->led_enabled || force) {
-//         if (state) {
-//             hw_gpio_set(GPIO_ID_LED);
-//         } else {
-//             hw_gpio_reset(GPIO_ID_LED);
-//         }
-//     } else {
-//         hw_gpio_reset(GPIO_ID_LED);
-//     }
-// }
+void led_activity_off (void) {
+    rtc_settings_t *settings = rtc_get_settings();
+    if (!activity_pulse && !error_active && settings->led_enabled) {
+        hw_gpio_reset(GPIO_ID_LED);
+    }
+}
 
-// static void led_update_error_mode (void) {
-//     if (error_mode) {
-//         if (!(cic_error || rtc_error)) {
-//             led_set_state(false, true);
-//             error_mode = false;
-//             act_timer = 0;
-//         }
-//     } else {
-//         if (cic_error || rtc_error) {
-//             led_set_state(false, true);
-//             error_mode = true;
-//             error_timer = 0;
-//         }
-//     }
-// }
-
-// static void led_process_errors (void) {
-//     if (error_timer == 0) {
-//         error_timer = LED_ERROR_TICKS_PERIOD;
-//         if (cic_error) {
-//             error_timer *= 1;
-//         } else if (rtc_error) {
-//             error_timer *= 2;
-//         }
-//         error_timer += LED_ERROR_TICKS_PERIOD;
-//     }
-
-//     if (error_timer > 0) {
-//         error_timer -= 1;
-//         if (error_timer >= LED_ERROR_TICKS_PERIOD) {
-//             uint32_t error_cycle = (error_timer % LED_ERROR_TICKS_PERIOD);
-//             if (error_cycle == LED_ERROR_TICKS_ON) {
-//                 led_set_state(true, true);
-//             }
-//             if (error_cycle == 0) {
-//                 led_set_state(false, true);
-//             }
-//         }
-//     }
-// }
-
-// static void led_process_act (void) {
-//     if (act_timer == 0) {
-//         if (current_act_counter != next_act_counter) {
-//             current_act_counter = next_act_counter;
-//             act_timer = LED_ACT_TICKS_PERIOD;
-//         }
-//     }
-
-//     if (act_timer > 0) {
-//         act_timer -= 1;
-//         if (act_timer == LED_ACT_TICKS_ON) {
-//             led_set_state(true, false);
-//         }
-//         if (act_timer == 0) {
-//             led_set_state(false, false);
-//         }
-//     }
-// }
+void led_activity_pulse (void) {
+    activity_pulse = true;
+    activity_pulse_timer = LED_PULSE_LENGTH_MS;
+}
 
 
 void led_blink_error (led_error_t error) {
-    // switch (error) {
-    //     case LED_ERROR_CIC:
-    //         cic_error = true;
-    //         break;
-    //     case LED_ERROR_RTC:
-    //         rtc_error = true;
-    //         break;
-    // }
+    switch (error) {
+        case LED_ERROR_CIC:
+            cic_error = true;
+            break;
+
+        case LED_ERROR_RTC:
+            rtc_error = true;
+            break;
+    }
+
+    error_active = (
+        cic_error |
+        rtc_error
+    );
 }
 
 void led_clear_error (led_error_t error) {
-    // switch (error) {
-    //     case LED_ERROR_CIC:
-    //         cic_error = false;
-    //         break;
-    //     case LED_ERROR_RTC:
-    //         rtc_error = false;
-    //         break;
-    // }
+    switch (error) {
+        case LED_ERROR_CIC:
+            cic_error = false;
+            break;
+
+        case LED_ERROR_RTC:
+            rtc_error = false;
+            break;
+    }
+
+    error_active = (
+        cic_error |
+        rtc_error
+    );
+
+    if (!error_active) {
+        activity_pulse = false;
+        activity_pulse_timer = 0;
+        error_timer = 0;
+    }
 }
 
-void led_blink_act (void) {
-    // next_act_counter += 1;
+
+void led_init (void) {
+    timer_countdown_start(TIMER_ID_LED, LED_REFRESH_PERIOD_MS);
 }
 
-// void led_task (void) {
-//     timer_init();
 
-//     while (1) {
-//         hw_tim_setup(TIM_ID_LED, LED_MS_PER_TICK, led_task_resume);
+void led_process (void) {
+    if (!timer_countdown_elapsed(TIMER_ID_LED)) {
+        return;
+    }
 
-//         led_update_error_mode();
+    timer_countdown_start(TIMER_ID_LED, LED_REFRESH_PERIOD_MS);
 
-//         if (error_mode) {
-//             led_process_errors();
-//         } else {
-//             led_process_act();
-//         }
+    if (error_active) {
+        int blinks = 0;
 
-//         timer_update();
+        if (cic_error) {
+            blinks = CIC_ERROR_BLINKS;
+        } else if (rtc_error) {
+            blinks = RTC_ERROR_BLINKS;
+        }
 
-//         task_yield();
-//     }
-// }
+        bool led_on = false;
+
+        for (int i = 0; i < blinks; i++) {
+            bool lower_bound = (error_timer >= (ERROR_BLINK_PERIOD_MS * (i * 2)));
+            bool upper_bound = (error_timer < (ERROR_BLINK_PERIOD_MS * ((i * 2) + 1)));
+            if (lower_bound && upper_bound) {
+                led_on = true;
+                break;
+            }
+        }
+
+        if (led_on) {
+            hw_gpio_set(GPIO_ID_LED);
+        } else {
+            hw_gpio_reset(GPIO_ID_LED);
+        }
+
+        error_timer += LED_REFRESH_PERIOD_MS;
+
+        if (error_timer >= ERROR_TOTAL_PERIOD_MS) {
+            error_timer = 0;
+        }
+
+        return;
+    }
+
+    if (activity_pulse) {
+        if (activity_pulse_timer > 0) {
+            hw_gpio_set(GPIO_ID_LED);
+        } else {
+            activity_pulse = false;
+            hw_gpio_reset(GPIO_ID_LED);
+            return;
+        }
+
+        activity_pulse_timer -= LED_REFRESH_PERIOD_MS;
+    }
+}
diff --git a/sw/controller/src/led.h b/sw/controller/src/led.h
index 4958d24..4a084a7 100644
--- a/sw/controller/src/led.h
+++ b/sw/controller/src/led.h
@@ -8,10 +8,16 @@ typedef enum {
 } led_error_t;
 
 
+void led_activity_on (void);
+void led_activity_off (void);
+void led_activity_pulse (void);
+
 void led_blink_error (led_error_t error);
 void led_clear_error (led_error_t error);
-void led_blink_act (void);
-// void led_task (void);
+
+void led_init (void);
+
+void led_process (void);
 
 
 #endif
diff --git a/sw/controller/src/primer.c b/sw/controller/src/primer.c
index 62bf8c8..b5083bb 100644
--- a/sw/controller/src/primer.c
+++ b/sw/controller/src/primer.c
@@ -19,7 +19,7 @@ static uint8_t primer_get_command (uint8_t *buffer, uint8_t *rx_length) {
     uint32_t received_crc32;
     uint8_t token[4];
 
-    while (1) {
+    while (true) {
         hw_crc32_reset();
 
         primer_get_and_calculate_crc32(token, 4, &calculated_crc32);
diff --git a/sw/controller/src/sd.c b/sw/controller/src/sd.c
index 3cae691..20498c4 100644
--- a/sw/controller/src/sd.c
+++ b/sw/controller/src/sd.c
@@ -1,6 +1,5 @@
 #include "fpga.h"
 #include "hw.h"
-#include "led.h"
 #include "sd.h"
 #include "timer.h"
 
@@ -192,7 +191,6 @@ static dat_err_t sd_dat_wait (uint16_t timeout_ms) {
     do {
         uint32_t sd_dat = fpga_reg_get(REG_SD_DAT);
         uint32_t sd_dma_scr = fpga_reg_get(REG_SD_DMA_SCR);
-        led_blink_act();
         if ((!(sd_dat & SD_DAT_BUSY)) && (!(sd_dma_scr & DMA_SCR_BUSY))) {
             if (sd_dat & SD_DAT_ERROR) {
                 sd_dat_abort();
@@ -222,8 +220,6 @@ bool sd_card_init (void) {
     p.card_initialized = true;
     p.rca = 0;
 
-    led_blink_act();
-
     sd_set_clock(CLOCK_400KHZ);
 
     sd_cmd(0, 0, RSP_NONE, NULL);
@@ -389,7 +385,6 @@ bool sd_write_sectors (uint32_t address, uint32_t sector, uint32_t count) {
 
     while (count > 0) {
         uint32_t blocks = ((count > DAT_BLOCK_MAX_COUNT) ? DAT_BLOCK_MAX_COUNT : count);
-        led_blink_act();
         if (sd_cmd(25, sector, RSP_R1, NULL)) {
             return true;
         }
@@ -422,7 +417,6 @@ bool sd_read_sectors (uint32_t address, uint32_t sector, uint32_t count) {
 
     while (count > 0) {
         uint32_t blocks = ((count > DAT_BLOCK_MAX_COUNT) ? DAT_BLOCK_MAX_COUNT : count);
-        led_blink_act();
         sd_dat_prepare(address, blocks, DAT_READ);
         if (sd_cmd(18, sector, RSP_R1, NULL)) {
             sd_dat_abort();
diff --git a/sw/controller/src/timer.c b/sw/controller/src/timer.c
index f2b91ea..ee50a10 100644
--- a/sw/controller/src/timer.c
+++ b/sw/controller/src/timer.c
@@ -2,7 +2,7 @@
 #include "timer.h"
 
 
-#define TIMER_PERIOD_MS     (50)
+#define TIMER_PERIOD_MS     (25)
 
 
 typedef struct {
diff --git a/sw/controller/src/timer.h b/sw/controller/src/timer.h
index fb5c72f..1adb086 100644
--- a/sw/controller/src/timer.h
+++ b/sw/controller/src/timer.h
@@ -8,6 +8,7 @@
 
 typedef enum {
     TIMER_ID_DD,
+    TIMER_ID_LED,
     TIMER_ID_RTC,
     TIMER_ID_SD,
     TIMER_ID_USB,