diff --git a/board/main.c b/board/main.c
index 52f12eca..40c29f42 100644
--- a/board/main.c
+++ b/board/main.c
@@ -170,7 +170,7 @@ void tick_handler(void) {
       #endif
 
       // set green LED to be controls allowed
-      current_board->set_led(LED_GREEN, controls_allowed);
+      current_board->set_led(LED_GREEN, controls_allowed | green_led_enabled);
 
       // turn off the blue LED, turned on by CAN
       // unless we are in power saving mode
diff --git a/board/main_comms.h b/board/main_comms.h
index 37520dc0..055289c3 100644
--- a/board/main_comms.h
+++ b/board/main_comms.h
@@ -418,6 +418,10 @@ int comms_control_handler(ControlPacket_t *req, uint8_t *resp) {
     case 0xf6:
       siren_enabled = (req->param1 != 0U);
       break;
+    // **** 0xf7: set green led enabled
+    case 0xf7:
+      green_led_enabled = (req->param1 != 0U);
+      break;
     // **** 0xf8: disable heartbeat checks
     case 0xf8:
       if (!is_car_safety_mode(current_safety_mode)) {
diff --git a/board/main_declarations.h b/board/main_declarations.h
index f9273886..4570c6e6 100644
--- a/board/main_declarations.h
+++ b/board/main_declarations.h
@@ -14,6 +14,7 @@ void pwm_set(TIM_TypeDef *TIM, uint8_t channel, uint8_t percentage);
 uint8_t hw_type = 0;
 const board *current_board;
 uint32_t uptime_cnt = 0;
+bool green_led_enabled = false;
 
 // heartbeat state
 uint32_t heartbeat_counter = 0;
diff --git a/python/__init__.py b/python/__init__.py
index 00d1462c..bcd9b836 100644
--- a/python/__init__.py
+++ b/python/__init__.py
@@ -715,8 +715,10 @@ class Panda:
 
   def serial_write(self, port_number, ln):
     ret = 0
+    if type(ln) == str:
+      ln = bytes(ln, 'utf-8')
     for i in range(0, len(ln), 0x20):
-      ret += self._handle.bulkWrite(2, struct.pack("B", port_number) + bytes(ln[i:i + 0x20], 'utf-8'))
+      ret += self._handle.bulkWrite(2, struct.pack("B", port_number) + ln[i:i + 0x20])
     return ret
 
   def serial_clear(self, port_number):
@@ -835,3 +837,7 @@ class Panda:
   # ****************** Siren *****************
   def set_siren(self, enabled):
     self._handle.controlWrite(Panda.REQUEST_OUT, 0xf6, int(enabled), 0, b'')
+
+  # ****************** Debug *****************
+  def set_green_led(self, enabled):
+    self._handle.controlWrite(Panda.REQUEST_OUT, 0xf7, int(enabled), 0, b'')