diff --git a/README.md b/README.md
index ff916ca..184cf30 100644
--- a/README.md
+++ b/README.md
@@ -64,8 +64,8 @@ Serial (HardwareSerial2)
 
 SDS011 pin | ESP32 pin | Notes
 -----------|-----------|----------
-TXD        | IO16      |
-RXD        | IO17      |
+TXD        | IO15      | (don't use IO16 together with PSRAM)
+RXD        | IO2       | (don't use IO17 together with PSRAM)
 GND        | GND       |
 25µm       | nc        |
 5V         | VUSB      | 5V
diff --git a/platformio.ini b/platformio.ini
index d503fed..59f4401 100644
--- a/platformio.ini
+++ b/platformio.ini
@@ -21,8 +21,8 @@ build_flags =
 ;    -DLOG_DEFAULT_LEVEL=ESP_LOG_VERBOSE
 ;    -DLOG_LOCAL_LEVEL=ESP_LOG_VERBOSE
 ;    -DCORE_DEBUG_LEVEL=ARDUHAL_LOG_LEVEL_VERBOSE
-;    -DBOARD_HAS_PSRAM
-;    -mfix-esp32-psram-cache-issue
+    -DBOARD_HAS_PSRAM
+    -mfix-esp32-psram-cache-issue
     -DWIFI_SSID="\"${sysenv.WIFI_SSID}\""
     -DWIFI_PASSWD="\"${sysenv.WIFI_PASSWD}\""
     -DWIFI_SSID2="\"${sysenv.WIFI_SSID2}\""
diff --git a/src/main.cpp b/src/main.cpp
index 42a9cdc..558e28d 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -738,6 +738,7 @@ void sendValues() {
 void setup()
 {
   Serial.begin(115200);
+  Serial2.begin(9600, SERIAL_8N1, /*rx*/15, /*tx*/2); // IMPORTANT: don't run with default pins 16, 17 as they are connected to PSRAM on boards that ship with it
 
   esp_sleep_wakeup_cause_t wakeup_reason = esp_sleep_get_wakeup_cause();
   ++bootCount;