diff --git a/src/main.cpp b/src/main.cpp
index 3f03ef6..d50123b 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -233,6 +233,7 @@ void sendESPNOW() {
 
   WiFi.forceSleepWake();
   delay(1);  // yield();
+  digitalWrite(LED_BUILTIN, LOW);
   WiFi.persistent(false); // don't load and save credentials to flash
   WiFi.mode(WIFI_STA);
   if (esp_now_init()==0) {
@@ -241,7 +242,8 @@ void sendESPNOW() {
       esp_now_add_peer(remoteMac, ESP_NOW_ROLE_SLAVE, WIFI_CHANNEL, NULL, 0);
       u8 bs[sizeof(sd)];
       memcpy(bs, &sd, sizeof(sd));
-      esp_now_send(NULL, bs, sizeof(sd)); // max ESP_NOW_MAX_DATA_LEN
+      for (int i=0; i<20; i++)
+        esp_now_send(NULL, bs, sizeof(sd)); // max ESP_NOW_MAX_DATA_LEN
 
     } else {
       Serial.println("error configuring ESP NOW");
@@ -253,6 +255,7 @@ void sendESPNOW() {
   WiFi.mode(WIFI_OFF);
   WiFi.forceSleepBegin();
   delay(1); // yield();
+  digitalWrite(LED_BUILTIN, HIGH);
   Serial.printf("sendESPNOW() took %d ms\n", millis()-espnowmillis);
 }
 
@@ -264,6 +267,9 @@ void ICACHE_RAM_ATTR ISR_geiger_impulse() {
 void setup() {
   Serial.begin(115200);
 
+  pinMode(LED_BUILTIN, OUTPUT);
+  digitalWrite(LED_BUILTIN, HIGH);  // turn OFF board led
+
   sds.begin(SDS_TX, SDS_RX);
   sds.mode_mon_300();
 
@@ -276,6 +282,8 @@ void setup() {
 
   pinMode(GEIGER_PIN, INPUT);
   attachInterrupt(digitalPinToInterrupt(GEIGER_PIN), ISR_geiger_impulse, FALLING);
+
+  Serial.println("ready."); Serial.flush();
 }
 
 void loop() {