diff --git a/board/drivers/clock_source.h b/board/drivers/clock_source.h
index d1b5724f..11b2fa32 100644
--- a/board/drivers/clock_source.h
+++ b/board/drivers/clock_source.h
@@ -1,6 +1,10 @@
 #define CLOCK_SOURCE_PERIOD_MS           50U
 #define CLOCK_SOURCE_PULSE_LEN_MS        2U
 
+void clock_source_set_period(uint8_t period) {
+  register_set(&(TIM1->ARR), ((period*10U) - 1U), 0xFFFFU);
+}
+
 void clock_source_init(void) {
   // Setup timer
   register_set(&(TIM1->PSC), ((APB2_TIMER_FREQ*100U)-1U), 0xFFFFU);           // Tick on 0.1 ms
diff --git a/board/main_comms.h b/board/main_comms.h
index c1591a06..b0b9823c 100644
--- a/board/main_comms.h
+++ b/board/main_comms.h
@@ -396,6 +396,10 @@ int comms_control_handler(ControlPacket_t *req, uint8_t *resp) {
       can_loopback = (req->param1 > 0U);
       can_init_all();
       break;
+    // **** 0xe6: set custom clock source period
+    case 0xe6:
+      clock_source_set_period(req->param1);
+      break;
     // **** 0xe7: set power save state
     case 0xe7:
       set_power_save_state(req->param1);
diff --git a/python/__init__.py b/python/__init__.py
index d4698c46..60a84ff4 100644
--- a/python/__init__.py
+++ b/python/__init__.py
@@ -1019,6 +1019,9 @@ class Panda:
   def set_green_led(self, enabled):
     self._handle.controlWrite(Panda.REQUEST_OUT, 0xf7, int(enabled), 0, b'')
 
+  def set_clock_source_period(self, period):
+    self._handle.controlWrite(Panda.REQUEST_OUT, 0xe6, period, 0, b'')
+
   # ****************** Logging *****************
   def get_logs(self, last_id=None, get_all=False):
     assert (last_id is None) or (0 <= last_id < 0xFFFF)