diff --git a/preload/apps/ecg/__init__.py b/preload/apps/ecg/__init__.py
index 4a2b8e53c3a80ef1552f9483cd66659525fcaa30..b359d2007c22e7616fee14569518e84716ed5d95 100644
--- a/preload/apps/ecg/__init__.py
+++ b/preload/apps/ecg/__init__.py
@@ -256,7 +256,8 @@ def toggle_leds():
 
     disp.update()
 
-def draw_leds(vmin,vmax):
+
+def draw_leds(vmin, vmax):
     # vmin should be in [0, -1]
     # vmax should be in [0, 1]
     global pulse, samples_since_last_pulse, last_pulse_blink
@@ -269,15 +270,23 @@ def draw_leds(vmin,vmax):
     # update led bar
     if led_mode & LED_FLAG_BAR:
         for i in reversed(range(6)):
-            leds.prep_hsv(5 + i, COLORS[5 + i] if vmin <= 0 and i <= vmin * -6 else (0, 0, 0))
+            leds.prep_hsv(
+                5 + i, COLORS[5 + i] if vmin <= 0 and i <= vmin * -6 else (0, 0, 0)
+            )
         for i in reversed(range(6)):
-            leds.prep_hsv(i, COLORS[i] if vmax >= 0 and 5 - i <= vmax * 6 else (0, 0, 0))
+            leds.prep_hsv(
+                i, COLORS[i] if vmax >= 0 and 5 - i <= vmax * 6 else (0, 0, 0)
+            )
     else:
         for i in range(11):
             leds.prep(i, (0, 0, 0))
 
     # blink red on pulse
-    if led_mode & LED_FLAG_PULSE and pulse > 0 and samples_since_last_pulse < last_pulse_blink:
+    if (
+        led_mode & LED_FLAG_PULSE
+        and pulse > 0
+        and samples_since_last_pulse < last_pulse_blink
+    ):
         last_pulse_blink = 0
         for i in range(4):
             leds.prep(11 + i, (255, 0, 0))
@@ -338,7 +347,9 @@ def draw_histogram():
         )
     else:
         led_range = last_sample_count if last_sample_count > 5 else 5
-        draw_leds(min(history[-led_range:]) / value_max, max(history[-led_range:]) / value_max)
+        draw_leds(
+            min(history[-led_range:]) / value_max, max(history[-led_range:]) / value_max
+        )
         if pulse < 0:
             disp.print(
                 current_mode + ("+Bias" if bias else ""),
@@ -375,9 +386,15 @@ def main():
     disp.clear(COLOR_BACKGROUND)
     disp.print("  BUTTONS ", posx=0, posy=0, fg=COLOR_TEXT, font=display.FONT20)
     disp.line(0, 20, 159, 20, col=COLOR_LINE)
-    disp.print("       Pause >", posx=0, posy=28, fg=COLOR_MODE_FINGER, font=display.FONT16)
-    disp.print(" Mode / Bias >", posx=0, posy=44, fg=COLOR_MODE_USB, font=display.FONT16)
-    disp.print("< LED/WriteLog", posx=0, posy=64, fg=COLOR_WRITE_BG, font=display.FONT16)
+    disp.print(
+        "       Pause >", posx=0, posy=28, fg=COLOR_MODE_FINGER, font=display.FONT16
+    )
+    disp.print(
+        " Mode / Bias >", posx=0, posy=44, fg=COLOR_MODE_USB, font=display.FONT16
+    )
+    disp.print(
+        "< LED/WriteLog", posx=0, posy=64, fg=COLOR_WRITE_BG, font=display.FONT16
+    )
     disp.update()
     utime.sleep(3)