diff --git a/radio/src/cli.cpp b/radio/src/cli.cpp
index 2824c5ed3..b7c00eb4e 100644
--- a/radio/src/cli.cpp
+++ b/radio/src/cli.cpp
@@ -1059,8 +1059,6 @@ static const etx_serial_init spIntmoduleSerialInitParams = {
   .stop_bits = ETX_StopBits_One,
   .word_length = ETX_WordLength_8,
   .rx_enable = true,
-  .on_receive = intmoduleFifoReceive,
-  .on_error = intmoduleFifoError,
 };
 
 static void spInternalModuleSetBaudRate(uint32_t baud)
diff --git a/radio/src/hal/serial_driver.h b/radio/src/hal/serial_driver.h
index 2a5658aec..3ebc84b50 100644
--- a/radio/src/hal/serial_driver.h
+++ b/radio/src/hal/serial_driver.h
@@ -47,8 +47,6 @@ typedef struct {
   uint8_t word_length;  // = ETX_WordLength_8;
   uint8_t rx_enable;    // = false;
 
-  void (*on_receive)(uint8_t data);  // = nullptr;
-  void (*on_error)();                // = nullptr;
 } etx_serial_init;
 
 struct etx_serial_callbacks_t {
diff --git a/radio/src/io/frsky_firmware_update.cpp b/radio/src/io/frsky_firmware_update.cpp
index 1ad1e9cd2..3aa2e4274 100644
--- a/radio/src/io/frsky_firmware_update.cpp
+++ b/radio/src/io/frsky_firmware_update.cpp
@@ -316,8 +316,6 @@ static const etx_serial_init serialInitParams = {
   .stop_bits = ETX_StopBits_One,
   .word_length = ETX_WordLength_8,
   .rx_enable = true,
-  .on_receive = intmoduleFifoReceive,
-  .on_error = intmoduleFifoError,
 };
 #endif
 
diff --git a/radio/src/io/frsky_pxx2.h b/radio/src/io/frsky_pxx2.h
index de13ff6ad..e48d99a9f 100644
--- a/radio/src/io/frsky_pxx2.h
+++ b/radio/src/io/frsky_pxx2.h
@@ -22,8 +22,10 @@
 #ifndef _IO_PXX2_H_
 #define _IO_PXX2_H_
 
-#include "../fifo.h"
-#include "../pulses/pxx.h"
+#include "fifo.h"
+#include "pulses/pxx.h"
+
+#include "board.h"
 
 class ModuleFifo : public Fifo<uint8_t, INTMODULE_FIFO_SIZE> {
   public:
diff --git a/radio/src/io/multi_firmware_update.cpp b/radio/src/io/multi_firmware_update.cpp
index 5cff0fdd2..3366144fa 100644
--- a/radio/src/io/multi_firmware_update.cpp
+++ b/radio/src/io/multi_firmware_update.cpp
@@ -82,8 +82,6 @@ static const etx_serial_init serialInitParams = {
   .stop_bits = ETX_StopBits_One,
   .word_length = ETX_WordLength_8,
   .rx_enable = true,
-  .on_receive = intmoduleFifoReceive,
-  .on_error = intmoduleFifoError,
 };
 
 class MultiInternalUpdateDriver: public MultiFirmwareUpdateDriver
diff --git a/radio/src/pulses/crossfire.cpp b/radio/src/pulses/crossfire.cpp
index ff5dbda2e..a38cfad80 100644
--- a/radio/src/pulses/crossfire.cpp
+++ b/radio/src/pulses/crossfire.cpp
@@ -111,31 +111,12 @@ static void crossfireSetupMixerScheduler(uint8_t module)
 }
 
 #if defined(INTERNAL_MODULE_CRSF)
-static void intmoduleCRSF_rx(uint8_t data)
-{
-  intmoduleFifo.push(data);
-
-#if !defined(SIMU)
-  // wakeup mixer when rx buffer is quarter full (16 bytes)
-  if (intmoduleFifo.size() >= 16) {
-    BaseType_t xHigherPriorityTaskWoken = pdFALSE;
-    xTaskNotifyFromISR(mixerTaskId.rtos_handle, 0, eNoAction,
-                       &xHigherPriorityTaskWoken);
-
-    // might effect a context switch on ISR exit
-    portYIELD_FROM_ISR(xHigherPriorityTaskWoken);
-  }
-#endif
-}
-
 static const etx_serial_init intmoduleCrossfireInitParams = {
   .baudrate = 0,
   .parity = ETX_Parity_None,
   .stop_bits = ETX_StopBits_One,
   .word_length = ETX_WordLength_8,
   .rx_enable = true,
-  .on_receive = intmoduleCRSF_rx,
-  .on_error = nullptr,
 };
 
 static void* crossfireInitInternal(uint8_t module)
@@ -146,9 +127,6 @@ static void* crossfireInitInternal(uint8_t module)
   etx_serial_init params(intmoduleCrossfireInitParams);
   params.baudrate = INT_CROSSFIRE_BAUDRATE;
 
-  // wakeup mixer when rx buffer is quarter full (16 bytes)
-  params.on_receive = intmoduleCRSF_rx;
-
   intmoduleFifo.clear();
   IntmoduleSerialDriver.init(&params);
   INTERNAL_MODULE_ON();
diff --git a/radio/src/pulses/multi.cpp b/radio/src/pulses/multi.cpp
index fb950ccbb..38e3f0a13 100644
--- a/radio/src/pulses/multi.cpp
+++ b/radio/src/pulses/multi.cpp
@@ -60,8 +60,6 @@ etx_serial_init multiSerialInitParams = {
     .stop_bits = ETX_StopBits_Two,
     .word_length = ETX_WordLength_9,
     .rx_enable = true,
-    .on_receive = intmoduleFifoReceive,
-    .on_error = intmoduleFifoError,
 };
 #endif
 
diff --git a/radio/src/pulses/pxx1.cpp b/radio/src/pulses/pxx1.cpp
index 833cb53b2..e170a8010 100644
--- a/radio/src/pulses/pxx1.cpp
+++ b/radio/src/pulses/pxx1.cpp
@@ -231,8 +231,6 @@ static const etx_serial_init pxx1SerialInit = {
   .stop_bits = ETX_StopBits_One,
   .word_length = ETX_WordLength_8,
   .rx_enable = false,
-  .on_receive = intmoduleFifoReceive,
-  .on_error = intmoduleFifoError,
 };
 
 static void* pxx1InitInternal(uint8_t module)
diff --git a/radio/src/pulses/pxx2.cpp b/radio/src/pulses/pxx2.cpp
index 6fe768266..a2b89778a 100644
--- a/radio/src/pulses/pxx2.cpp
+++ b/radio/src/pulses/pxx2.cpp
@@ -36,8 +36,6 @@ const etx_serial_init pxx2SerialInitParams = {
     .stop_bits = ETX_StopBits_One,
     .word_length = ETX_WordLength_8,
     .rx_enable = true,
-    .on_receive = intmoduleFifoReceive,
-    .on_error = intmoduleFifoError,
 };
 #endif
 
@@ -717,8 +715,6 @@ static const etx_serial_init pxx2ExtSerialInitParams = {
   .stop_bits = ETX_StopBits_One,
   .word_length = ETX_WordLength_8,
   .rx_enable = true,
-  .on_receive = extmoduleFifoReceive,
-  .on_error = extmoduleFifoError,
 };
 
 static void* pxx2InitLowSpeed(uint8_t module)
diff --git a/radio/src/serial.cpp b/radio/src/serial.cpp
index 45ba48871..6006ec144 100644
--- a/radio/src/serial.cpp
+++ b/radio/src/serial.cpp
@@ -290,8 +290,6 @@ void serialInit(uint8_t port_nr, int mode)
     .stop_bits = ETX_StopBits_One,
     .word_length = ETX_WordLength_8,
     .rx_enable = false,
-    .on_receive = nullptr,
-    .on_error = nullptr,
   };
 
   bool power_required = false;
diff --git a/radio/src/targets/common/arm/stm32/aux_serial_driver.cpp b/radio/src/targets/common/arm/stm32/aux_serial_driver.cpp
index 7e19ef328..bc5c78ef5 100644
--- a/radio/src/targets/common/arm/stm32/aux_serial_driver.cpp
+++ b/radio/src/targets/common/arm/stm32/aux_serial_driver.cpp
@@ -52,7 +52,7 @@ static void* aux_serial_init(const SerialState* st, const etx_serial_init* param
 {
   stm32_usart_init(st->usart, params);
   
-  if (params->rx_enable && st->usart->rxDMA && !params->on_receive) {
+  if (params->rx_enable && st->usart->rxDMA) {
     st->rxFifo->clear();
     stm32_usart_init_rx_dma(st->usart, st->rxFifo->buffer(), st->rxFifo->size());
   }
diff --git a/radio/src/targets/common/arm/stm32/extmodule_serial_driver.cpp b/radio/src/targets/common/arm/stm32/extmodule_serial_driver.cpp
index 3854367ce..dfc2947f1 100644
--- a/radio/src/targets/common/arm/stm32/extmodule_serial_driver.cpp
+++ b/radio/src/targets/common/arm/stm32/extmodule_serial_driver.cpp
@@ -38,19 +38,12 @@ void extmoduleFifoReceive(uint8_t data)
   extmoduleFifo.push(data);
 }
 
-void extmoduleFifoError()
-{
-  extmoduleFifo.errors++;
-}
-
 static const etx_serial_init extmoduleSerialParams = {
   .baudrate = 0,
   .parity = ETX_Parity_None,
   .stop_bits = ETX_StopBits_One,
   .word_length = ETX_WordLength_8,
   .rx_enable = true,
-  .on_receive = extmoduleFifoReceive,
-  .on_error = extmoduleFifoError,
 };
 
 static const LL_GPIO_InitTypeDef extmoduleUSART_PinDef = {
@@ -80,8 +73,8 @@ static void* extmoduleSerialStart(const etx_serial_init* params)
 {
   if (!params) return nullptr;
     
-  extmodule_driver.on_receive = params->on_receive;
-  extmodule_driver.on_error = params->on_error;
+  extmodule_driver.on_receive = extmoduleFifoReceive;
+  extmodule_driver.on_error = nullptr;
 
   // UART config
   stm32_usart_init(&extmoduleUSART, params);
diff --git a/radio/src/targets/common/arm/stm32/intmodule_serial_driver.cpp b/radio/src/targets/common/arm/stm32/intmodule_serial_driver.cpp
index 3f38ce167..30b381b67 100755
--- a/radio/src/targets/common/arm/stm32/intmodule_serial_driver.cpp
+++ b/radio/src/targets/common/arm/stm32/intmodule_serial_driver.cpp
@@ -23,9 +23,9 @@
 #include "intmodule_serial_driver.h"
 #include "stm32_usart_driver.h"
 #include "board.h"
+#include "fifo.h"
 
-#include "io/frsky_pxx2.h"
-ModuleFifo intmoduleFifo;
+Fifo<uint8_t, INTMODULE_FIFO_SIZE> intmoduleFifo;
 
 #if !defined(INTMODULE_DMA_STREAM)
 static uint8_t * intmoduleTxBufferData;
@@ -54,16 +54,11 @@ static etx_serial_callbacks_t intmodule_driver = {
 };
 
 // TODO: move this somewhere else
-void intmoduleFifoReceive(uint8_t data)
+static void intmoduleFifoReceive(uint8_t data)
 {
   intmoduleFifo.push(data);
 }
 
-void intmoduleFifoError()
-{
-  intmoduleFifo.errors++;
-}
-
 static const LL_GPIO_InitTypeDef intmoduleUSART_PinDef = {
   .Pin = INTMODULE_TX_GPIO_PIN | INTMODULE_RX_GPIO_PIN,
   .Mode = LL_GPIO_MODE_ALTERNATE,
@@ -110,8 +105,8 @@ void* intmoduleSerialStart(const etx_serial_init* params)
   //  - the UART seems to block when initialised with baudrate = 0
 
   // init callbacks
-  intmodule_driver.on_receive = params->on_receive;
-  intmodule_driver.on_error = params->on_error;
+  intmodule_driver.on_receive = intmoduleFifoReceive;
+  intmodule_driver.on_error = nullptr;
 
   stm32_usart_init(&intmoduleUSART, params);
   return nullptr;
diff --git a/radio/src/targets/common/arm/stm32/intmodule_serial_driver.h b/radio/src/targets/common/arm/stm32/intmodule_serial_driver.h
index 4ae11f99a..4ee4a63f9 100644
--- a/radio/src/targets/common/arm/stm32/intmodule_serial_driver.h
+++ b/radio/src/targets/common/arm/stm32/intmodule_serial_driver.h
@@ -26,8 +26,4 @@
 
 #define INTMODULE_USART_IRQ_PRIORITY 6
 
-// Callbacks using intmoduleFifo
-void intmoduleFifoReceive(uint8_t data);
-void intmoduleFifoError();
-
 extern const etx_serial_driver_t IntmoduleSerialDriver;
diff --git a/radio/src/targets/common/arm/stm32/timers_driver.cpp b/radio/src/targets/common/arm/stm32/timers_driver.cpp
index d058f51ba..1fe4644c3 100644
--- a/radio/src/targets/common/arm/stm32/timers_driver.cpp
+++ b/radio/src/targets/common/arm/stm32/timers_driver.cpp
@@ -67,8 +67,7 @@ static void interrupt1ms()
 #endif
 
   // 5ms loop
-  if (pre_scale == 5 || pre_scale == 10)
-  {
+  if (pre_scale == 5 || pre_scale == 10) {
 #if defined(HAPTIC)
     DEBUG_TIMER_START(debugTimerHaptic);
     HAPTIC_HEARTBEAT();
@@ -77,8 +76,7 @@ static void interrupt1ms()
   }
   
   // 10ms loop
-  if (pre_scale == 10)
-	{
+  if (pre_scale == 10) {
     pre_scale = 0;
     DEBUG_TIMER_START(debugTimerPer10ms);
     DEBUG_TIMER_SAMPLE(debugTimerPer10msPeriod);
diff --git a/radio/src/targets/horus/board.h b/radio/src/targets/horus/board.h
index 269134727..e5377eb18 100644
--- a/radio/src/targets/horus/board.h
+++ b/radio/src/targets/horus/board.h
@@ -615,6 +615,7 @@ int32_t getVolume();
 #define VOLUME_LEVEL_DEF               12
 
 // Telemetry driver
+#define INTMODULE_FIFO_SIZE            512
 #define TELEMETRY_FIFO_SIZE            512
 void telemetryPortInit(uint32_t baudrate, uint8_t mode);
 void telemetryPortSetDirectionInput();
diff --git a/radio/src/telemetry/frsky_pxx2.cpp b/radio/src/telemetry/frsky_pxx2.cpp
index ff52b081d..9c0fb04a7 100644
--- a/radio/src/telemetry/frsky_pxx2.cpp
+++ b/radio/src/telemetry/frsky_pxx2.cpp
@@ -29,6 +29,8 @@
 #include "intmodule_serial_driver.h"
 #endif
 
+static_assert(PXX2_FRAME_MAXLENGTH <= INTMODULE_FIFO_SIZE);
+
 void processGetHardwareInfoFrame(uint8_t module, const uint8_t * frame)
 {
   if (moduleState[module].mode != MODULE_MODE_GET_HARDWARE_INFO) {
diff --git a/radio/src/telemetry/telemetry.cpp b/radio/src/telemetry/telemetry.cpp
index 0c48b8283..e15ffe331 100644
--- a/radio/src/telemetry/telemetry.cpp
+++ b/radio/src/telemetry/telemetry.cpp
@@ -275,6 +275,9 @@ void telemetryWakeup()
 {
   uint8_t requiredTelemetryProtocol = modelTelemetryProtocol();
 
+  // TODO: needs to be moved to protocol/module init
+  //       as-is, it implies only ONE telemetry protocol
+  //       enabled at the same time
   if (telemetryProtocol != requiredTelemetryProtocol) {
     telemetryInit(requiredTelemetryProtocol);
   }