From fffb1fae9f6c43997c7ee0993e68ec7cd80ebb17 Mon Sep 17 00:00:00 2001
From: jgromes <jan.gromes@gmail.com>
Date: Sat, 13 Jul 2024 16:42:46 +0100
Subject: [PATCH] [PHY] Make transmit data const (#1156)

---
 src/modules/CC1101/CC1101.cpp                 | 6 +++---
 src/modules/CC1101/CC1101.h                   | 4 ++--
 src/modules/LR11x0/LR11x0.cpp                 | 8 ++++----
 src/modules/LR11x0/LR11x0.h                   | 4 ++--
 src/modules/RF69/RF69.cpp                     | 6 +++---
 src/modules/RF69/RF69.h                       | 4 ++--
 src/modules/SX126x/SX126x.cpp                 | 7 +++----
 src/modules/SX126x/SX126x.h                   | 4 ++--
 src/modules/SX127x/SX127x.cpp                 | 6 +++---
 src/modules/SX127x/SX127x.h                   | 4 ++--
 src/modules/SX128x/SX128x.cpp                 | 8 ++++----
 src/modules/SX128x/SX128x.h                   | 4 ++--
 src/modules/Si443x/Si443x.cpp                 | 6 +++---
 src/modules/Si443x/Si443x.h                   | 4 ++--
 src/modules/nRF24/nRF24.cpp                   | 6 +++---
 src/modules/nRF24/nRF24.h                     | 4 ++--
 src/protocols/PhysicalLayer/PhysicalLayer.cpp | 4 ++--
 src/protocols/PhysicalLayer/PhysicalLayer.h   | 4 ++--
 18 files changed, 46 insertions(+), 47 deletions(-)

diff --git a/src/modules/CC1101/CC1101.cpp b/src/modules/CC1101/CC1101.cpp
index 7d08ac7a..45a5558a 100644
--- a/src/modules/CC1101/CC1101.cpp
+++ b/src/modules/CC1101/CC1101.cpp
@@ -98,7 +98,7 @@ void CC1101::reset() {
   SPIsendCommand(RADIOLIB_CC1101_CMD_RESET);
 }
 
-int16_t CC1101::transmit(uint8_t* data, size_t len, uint8_t addr) {
+int16_t CC1101::transmit(const uint8_t* data, size_t len, uint8_t addr) {
   // calculate timeout (5ms + 500 % of expected time-on-air)
   RadioLibTime_t timeout = 5 + (RadioLibTime_t)((((float)(len * 8)) / this->bitRate) * 5);
 
@@ -289,7 +289,7 @@ void CC1101::clearGdo2Action() {
   this->mod->hal->detachInterrupt(this->mod->hal->pinToInterrupt(this->mod->getGpio()));
 }
 
-int16_t CC1101::startTransmit(uint8_t* data, size_t len, uint8_t addr) {
+int16_t CC1101::startTransmit(const uint8_t* data, size_t len, uint8_t addr) {
   // check packet length
   if(len > RADIOLIB_CC1101_MAX_PACKET_LENGTH) {
     return(RADIOLIB_ERR_PACKET_TOO_LONG);
@@ -317,7 +317,7 @@ int16_t CC1101::startTransmit(uint8_t* data, size_t len, uint8_t addr) {
   }
 
   // fill the FIFO
-  SPIwriteRegisterBurst(RADIOLIB_CC1101_REG_FIFO, data, len);
+  SPIwriteRegisterBurst(RADIOLIB_CC1101_REG_FIFO, const_cast<uint8_t*>(data), len);
 
   // set RF switch (if present)
   this->mod->setRfSwitchState(Module::MODE_TX);
diff --git a/src/modules/CC1101/CC1101.h b/src/modules/CC1101/CC1101.h
index 55eb9a84..cb5efe71 100644
--- a/src/modules/CC1101/CC1101.h
+++ b/src/modules/CC1101/CC1101.h
@@ -575,7 +575,7 @@ class CC1101: public PhysicalLayer {
       \param addr Address to send the data to. Will only be added if address filtering was enabled.
       \returns \ref status_codes
     */
-    int16_t transmit(uint8_t* data, size_t len, uint8_t addr = 0) override;
+    int16_t transmit(const uint8_t* data, size_t len, uint8_t addr = 0) override;
 
     /*!
       \brief Blocking binary receive method.
@@ -687,7 +687,7 @@ class CC1101: public PhysicalLayer {
       \param addr Address to send the data to. Will only be added if address filtering was enabled.
       \returns \ref status_codes
     */
-    int16_t startTransmit(uint8_t* data, size_t len, uint8_t addr = 0) override;
+    int16_t startTransmit(const uint8_t* data, size_t len, uint8_t addr = 0) override;
 
     /*!
       \brief Clean up after transmission is done.
diff --git a/src/modules/LR11x0/LR11x0.cpp b/src/modules/LR11x0/LR11x0.cpp
index 906c56c8..dff27ceb 100644
--- a/src/modules/LR11x0/LR11x0.cpp
+++ b/src/modules/LR11x0/LR11x0.cpp
@@ -130,7 +130,7 @@ int16_t LR11x0::reset() {
   return(RADIOLIB_ERR_NONE);
 }
 
-int16_t LR11x0::transmit(uint8_t* data, size_t len, uint8_t addr) {
+int16_t LR11x0::transmit(const uint8_t* data, size_t len, uint8_t addr) {
    // set mode to standby
   int16_t state = standby();
   RADIOLIB_ASSERT(state);
@@ -363,7 +363,7 @@ void LR11x0::clearPacketSentAction() {
   this->clearIrqAction();
 }
 
-int16_t LR11x0::startTransmit(uint8_t* data, size_t len, uint8_t addr) {
+int16_t LR11x0::startTransmit(const uint8_t* data, size_t len, uint8_t addr) {
   // suppress unused variable warning
   (void)addr;
 
@@ -401,12 +401,12 @@ int16_t LR11x0::startTransmit(uint8_t* data, size_t len, uint8_t addr) {
   if(modem == RADIOLIB_LR11X0_PACKET_TYPE_LR_FHSS) {
     // in LR-FHSS mode, the packet is built by the device
     // TODO add configurable grid step and device offset
-    state = lrFhssBuildFrame(this->lrFhssHdrCount, this->lrFhssCr, RADIOLIB_LR11X0_LR_FHSS_GRID_STEP_FCC, true, this->lrFhssBw, this->lrFhssHopSeq, 0, data, len);
+    state = lrFhssBuildFrame(this->lrFhssHdrCount, this->lrFhssCr, RADIOLIB_LR11X0_LR_FHSS_GRID_STEP_FCC, true, this->lrFhssBw, this->lrFhssHopSeq, 0, const_cast<uint8_t*>(data), len);
     RADIOLIB_ASSERT(state);
 
   } else {
     // write packet to buffer
-    state = writeBuffer8(data, len);
+    state = writeBuffer8(const_cast<uint8_t*>(data), len);
     RADIOLIB_ASSERT(state);
 
   }
diff --git a/src/modules/LR11x0/LR11x0.h b/src/modules/LR11x0/LR11x0.h
index e00c6bf6..9177569c 100644
--- a/src/modules/LR11x0/LR11x0.h
+++ b/src/modules/LR11x0/LR11x0.h
@@ -797,7 +797,7 @@ class LR11x0: public PhysicalLayer {
       \param addr Address to send the data to. Will only be added if address filtering was enabled.
       \returns \ref status_codes
     */
-    int16_t transmit(uint8_t* data, size_t len, uint8_t addr = 0) override;
+    int16_t transmit(const uint8_t* data, size_t len, uint8_t addr = 0) override;
 
     /*!
       \brief Blocking binary receive method.
@@ -911,7 +911,7 @@ class LR11x0: public PhysicalLayer {
       \param addr Address to send the data to. Will only be added if address filtering was enabled.
       \returns \ref status_codes
     */
-    int16_t startTransmit(uint8_t* data, size_t len, uint8_t addr = 0) override;
+    int16_t startTransmit(const uint8_t* data, size_t len, uint8_t addr = 0) override;
 
     /*!
       \brief Clean up after transmission is done.
diff --git a/src/modules/RF69/RF69.cpp b/src/modules/RF69/RF69.cpp
index 260962a5..d5a07c9e 100644
--- a/src/modules/RF69/RF69.cpp
+++ b/src/modules/RF69/RF69.cpp
@@ -98,7 +98,7 @@ void RF69::reset() {
   this->mod->hal->delay(10);
 }
 
-int16_t RF69::transmit(uint8_t* data, size_t len, uint8_t addr) {
+int16_t RF69::transmit(const uint8_t* data, size_t len, uint8_t addr) {
   // calculate timeout (5ms + 500 % of expected time-on-air)
   RadioLibTime_t timeout = 5 + (RadioLibTime_t)((((float)(len * 8)) / this->bitRate) * 5);
 
@@ -380,7 +380,7 @@ bool RF69::fifoGet(volatile uint8_t* data, int totalLen, volatile int* rcvLen) {
   return(false);
 }
 
-int16_t RF69::startTransmit(uint8_t* data, size_t len, uint8_t addr) {
+int16_t RF69::startTransmit(const uint8_t* data, size_t len, uint8_t addr) {
   // set mode to standby
   int16_t state = setMode(RADIOLIB_RF69_STANDBY);
   RADIOLIB_ASSERT(state);
@@ -413,7 +413,7 @@ int16_t RF69::startTransmit(uint8_t* data, size_t len, uint8_t addr) {
     packetLen = RADIOLIB_RF69_FIFO_THRESH - 1;
     this->mod->SPIsetRegValue(RADIOLIB_RF69_REG_FIFO_THRESH, RADIOLIB_RF69_TX_START_CONDITION_FIFO_NOT_EMPTY, 7, 7);
   }
-  this->mod->SPIwriteRegisterBurst(RADIOLIB_RF69_REG_FIFO, data, packetLen);
+  this->mod->SPIwriteRegisterBurst(RADIOLIB_RF69_REG_FIFO, const_cast<uint8_t*>(data), packetLen);
 
   // this is a hack, but it seems than in Stream mode, Rx FIFO level is getting triggered 1 byte before it should
   // just add a padding byte that can be dropped without consequence
diff --git a/src/modules/RF69/RF69.h b/src/modules/RF69/RF69.h
index 7d77ef66..a7a25e49 100644
--- a/src/modules/RF69/RF69.h
+++ b/src/modules/RF69/RF69.h
@@ -523,7 +523,7 @@ class RF69: public PhysicalLayer {
       \param addr Address to send the data to. Will only be added if address filtering was enabled.
       \returns \ref status_codes
     */
-    int16_t transmit(uint8_t* data, size_t len, uint8_t addr = 0) override;
+    int16_t transmit(const uint8_t* data, size_t len, uint8_t addr = 0) override;
 
     /*!
       \brief Blocking binary receive method.
@@ -685,7 +685,7 @@ class RF69: public PhysicalLayer {
       \param addr Address to send the data to. Will only be added if address filtering was enabled.
       \returns \ref status_codes
     */
-    int16_t startTransmit(uint8_t* data, size_t len, uint8_t addr = 0) override;
+    int16_t startTransmit(const uint8_t* data, size_t len, uint8_t addr = 0) override;
 
     /*!
       \brief Clean up after transmission is done.
diff --git a/src/modules/SX126x/SX126x.cpp b/src/modules/SX126x/SX126x.cpp
index 591346d4..6b4cdda5 100644
--- a/src/modules/SX126x/SX126x.cpp
+++ b/src/modules/SX126x/SX126x.cpp
@@ -228,7 +228,7 @@ int16_t SX126x::reset(bool verify) {
   }
 }
 
-int16_t SX126x::transmit(uint8_t* data, size_t len, uint8_t addr) {
+int16_t SX126x::transmit(const uint8_t* data, size_t len, uint8_t addr) {
   // set mode to standby
   int16_t state = standby();
   RADIOLIB_ASSERT(state);
@@ -512,8 +512,7 @@ void SX126x::clearChannelScanAction() {
   this->clearDio1Action();
 }
 
-
-int16_t SX126x::startTransmit(uint8_t* data, size_t len, uint8_t addr) {
+int16_t SX126x::startTransmit(const uint8_t* data, size_t len, uint8_t addr) {
   // suppress unused variable warning
   (void)addr;
 
@@ -548,7 +547,7 @@ int16_t SX126x::startTransmit(uint8_t* data, size_t len, uint8_t addr) {
   RADIOLIB_ASSERT(state);
 
   // write packet to buffer
-  state = writeBuffer(data, len);
+    state = writeBuffer(const_cast<uint8_t*>(data), len);
   RADIOLIB_ASSERT(state);
 
   // clear interrupt flags
diff --git a/src/modules/SX126x/SX126x.h b/src/modules/SX126x/SX126x.h
index f05e5d9a..0fc9b6ac 100644
--- a/src/modules/SX126x/SX126x.h
+++ b/src/modules/SX126x/SX126x.h
@@ -506,7 +506,7 @@ class SX126x: public PhysicalLayer {
       \param addr Address to send the data to. Will only be added if address filtering was enabled.
       \returns \ref status_codes
     */
-    int16_t transmit(uint8_t* data, size_t len, uint8_t addr = 0) override;
+    int16_t transmit(const uint8_t* data, size_t len, uint8_t addr = 0) override;
 
     /*!
       \brief Blocking binary receive method.
@@ -630,7 +630,7 @@ class SX126x: public PhysicalLayer {
       \param addr Address to send the data to. Will only be added if address filtering was enabled.
       \returns \ref status_codes
     */
-    int16_t startTransmit(uint8_t* data, size_t len, uint8_t addr = 0) override;
+    int16_t startTransmit(const uint8_t* data, size_t len, uint8_t addr = 0) override;
 
     /*!
       \brief Clean up after transmission is done.
diff --git a/src/modules/SX127x/SX127x.cpp b/src/modules/SX127x/SX127x.cpp
index d81671e8..010c209b 100644
--- a/src/modules/SX127x/SX127x.cpp
+++ b/src/modules/SX127x/SX127x.cpp
@@ -141,7 +141,7 @@ int16_t SX127x::beginFSK(uint8_t* chipVersions, uint8_t numVersions, float freqD
   return(state);
 }
 
-int16_t SX127x::transmit(uint8_t* data, size_t len, uint8_t addr) {
+int16_t SX127x::transmit(const uint8_t* data, size_t len, uint8_t addr) {
   // set mode to standby
   int16_t state = setMode(RADIOLIB_SX127X_STANDBY);
   RADIOLIB_ASSERT(state);
@@ -549,7 +549,7 @@ bool SX127x::fifoGet(volatile uint8_t* data, int totalLen, volatile int* rcvLen)
   return(false);
 }
 
-int16_t SX127x::startTransmit(uint8_t* data, size_t len, uint8_t addr) {
+int16_t SX127x::startTransmit(const uint8_t* data, size_t len, uint8_t addr) {
   // set mode to standby
   int16_t state = setMode(RADIOLIB_SX127X_STANDBY);
 
@@ -609,7 +609,7 @@ int16_t SX127x::startTransmit(uint8_t* data, size_t len, uint8_t addr) {
     packetLen = RADIOLIB_SX127X_FIFO_THRESH - 1;
     this->mod->SPIsetRegValue(RADIOLIB_SX127X_REG_FIFO_THRESH, RADIOLIB_SX127X_TX_START_FIFO_NOT_EMPTY, 7, 7);
   }
-  this->mod->SPIwriteRegisterBurst(RADIOLIB_SX127X_REG_FIFO, data, packetLen);
+  this->mod->SPIwriteRegisterBurst(RADIOLIB_SX127X_REG_FIFO, const_cast<uint8_t*>(data), packetLen);
 
   // set RF switch (if present)
   this->mod->setRfSwitchState(Module::MODE_TX);
diff --git a/src/modules/SX127x/SX127x.h b/src/modules/SX127x/SX127x.h
index a9711d81..7e8d5e5a 100644
--- a/src/modules/SX127x/SX127x.h
+++ b/src/modules/SX127x/SX127x.h
@@ -633,7 +633,7 @@ class SX127x: public PhysicalLayer {
       \param addr Node address to transmit the packet to. Only used in FSK mode.
       \returns \ref status_codes
     */
-    int16_t transmit(uint8_t* data, size_t len, uint8_t addr = 0) override;
+    int16_t transmit(const uint8_t* data, size_t len, uint8_t addr = 0) override;
 
     /*!
       \brief Binary receive method. Will attempt to receive arbitrary binary data up to 255 bytes long using %LoRa or up to 63 bytes using FSK modem.
@@ -797,7 +797,7 @@ class SX127x: public PhysicalLayer {
       \param addr Node address to transmit the packet to. Only used in FSK mode.
       \returns \ref status_codes
     */
-    int16_t startTransmit(uint8_t* data, size_t len, uint8_t addr = 0) override;
+    int16_t startTransmit(const uint8_t* data, size_t len, uint8_t addr = 0) override;
 
     /*!
       \brief Clean up after transmission is done.
diff --git a/src/modules/SX128x/SX128x.cpp b/src/modules/SX128x/SX128x.cpp
index f35ccc26..8f41a797 100644
--- a/src/modules/SX128x/SX128x.cpp
+++ b/src/modules/SX128x/SX128x.cpp
@@ -301,7 +301,7 @@ int16_t SX128x::reset(bool verify) {
   }
 }
 
-int16_t SX128x::transmit(uint8_t* data, size_t len, uint8_t addr) {
+int16_t SX128x::transmit(const uint8_t* data, size_t len, uint8_t addr) {
   // check packet length
   if(len > RADIOLIB_SX128X_MAX_PACKET_LENGTH) {
     return(RADIOLIB_ERR_PACKET_TOO_LONG);
@@ -485,7 +485,7 @@ void SX128x::clearPacketSentAction() {
   this->clearDio1Action();
 }
 
-int16_t SX128x::startTransmit(uint8_t* data, size_t len, uint8_t addr) {
+int16_t SX128x::startTransmit(const uint8_t* data, size_t len, uint8_t addr) {
   // suppress unused variable warning
   (void)addr;
 
@@ -519,10 +519,10 @@ int16_t SX128x::startTransmit(uint8_t* data, size_t len, uint8_t addr) {
   // write packet to buffer
   if(modem == RADIOLIB_SX128X_PACKET_TYPE_BLE) {
     // first 2 bytes of BLE payload are PDU header
-    state = writeBuffer(data, len, 2);
+    state = writeBuffer(const_cast<uint8_t*>(data), len, 2);
     RADIOLIB_ASSERT(state);
   } else {
-    state = writeBuffer(data, len);
+    state = writeBuffer(const_cast<uint8_t*>(data), len);
     RADIOLIB_ASSERT(state);
   }
 
diff --git a/src/modules/SX128x/SX128x.h b/src/modules/SX128x/SX128x.h
index c93d79c4..6ce9164f 100644
--- a/src/modules/SX128x/SX128x.h
+++ b/src/modules/SX128x/SX128x.h
@@ -426,7 +426,7 @@ class SX128x: public PhysicalLayer {
       \param addr Address to send the data to. Unsupported, compatibility only.
       \returns \ref status_codes
     */
-    int16_t transmit(uint8_t* data, size_t len, uint8_t addr = 0) override;
+    int16_t transmit(const uint8_t* data, size_t len, uint8_t addr = 0) override;
 
     /*!
       \brief Blocking binary receive method.
@@ -530,7 +530,7 @@ class SX128x: public PhysicalLayer {
       \param addr Address to send the data to. Unsupported, compatibility only.
       \returns \ref status_codes
     */
-    int16_t startTransmit(uint8_t* data, size_t len, uint8_t addr = 0) override;
+    int16_t startTransmit(const uint8_t* data, size_t len, uint8_t addr = 0) override;
 
     /*!
       \brief Clean up after transmission is done.
diff --git a/src/modules/Si443x/Si443x.cpp b/src/modules/Si443x/Si443x.cpp
index 7dfd8eb8..4ba1b21c 100644
--- a/src/modules/Si443x/Si443x.cpp
+++ b/src/modules/Si443x/Si443x.cpp
@@ -71,7 +71,7 @@ void Si443x::reset() {
   this->mod->hal->delay(100);
 }
 
-int16_t Si443x::transmit(uint8_t* data, size_t len, uint8_t addr) {
+int16_t Si443x::transmit(const uint8_t* data, size_t len, uint8_t addr) {
   // calculate timeout (5ms + 500 % of expected time-on-air)
   RadioLibTime_t timeout = 5 + (uint32_t)((((float)(len * 8)) / this->bitRate) * 5);
 
@@ -226,7 +226,7 @@ void Si443x::clearPacketSentAction() {
   this->clearIrqAction();
 }
 
-int16_t Si443x::startTransmit(uint8_t* data, size_t len, uint8_t addr) {
+int16_t Si443x::startTransmit(const uint8_t* data, size_t len, uint8_t addr) {
   // check packet length
   if(len > RADIOLIB_SI443X_MAX_PACKET_LENGTH) {
     return(RADIOLIB_ERR_PACKET_TOO_LONG);
@@ -252,7 +252,7 @@ int16_t Si443x::startTransmit(uint8_t* data, size_t len, uint8_t addr) {
   (void)addr;
 
   // write packet to FIFO
-  this->mod->SPIwriteRegisterBurst(RADIOLIB_SI443X_REG_FIFO_ACCESS, data, len);
+  this->mod->SPIwriteRegisterBurst(RADIOLIB_SI443X_REG_FIFO_ACCESS, const_cast<uint8_t*>(data), len);
 
   // set RF switch (if present)
   this->mod->setRfSwitchState(Module::MODE_TX);
diff --git a/src/modules/Si443x/Si443x.h b/src/modules/Si443x/Si443x.h
index 24f8bb06..c100b04e 100644
--- a/src/modules/Si443x/Si443x.h
+++ b/src/modules/Si443x/Si443x.h
@@ -591,7 +591,7 @@ class Si443x: public PhysicalLayer {
       \param addr Node address to transmit the packet to.
       \returns \ref status_codes
     */
-    int16_t transmit(uint8_t* data, size_t len, uint8_t addr = 0) override;
+    int16_t transmit(const uint8_t* data, size_t len, uint8_t addr = 0) override;
 
     /*!
       \brief Binary receive method. Will attempt to receive arbitrary binary data up to 64 bytes long.
@@ -683,7 +683,7 @@ class Si443x: public PhysicalLayer {
       \param addr Node address to transmit the packet to.
       \returns \ref status_codes
     */
-    int16_t startTransmit(uint8_t* data, size_t len, uint8_t addr = 0) override;
+    int16_t startTransmit(const uint8_t* data, size_t len, uint8_t addr = 0) override;
 
     /*!
       \brief Clean up after transmission is done.
diff --git a/src/modules/nRF24/nRF24.cpp b/src/modules/nRF24/nRF24.cpp
index 09d8bf09..deafef27 100644
--- a/src/modules/nRF24/nRF24.cpp
+++ b/src/modules/nRF24/nRF24.cpp
@@ -82,7 +82,7 @@ int16_t nRF24::standby(uint8_t mode) {
   return(this->mod->SPIsetRegValue(RADIOLIB_NRF24_REG_CONFIG, mode, 1, 1));
 }
 
-int16_t nRF24::transmit(uint8_t* data, size_t len, uint8_t addr) {
+int16_t nRF24::transmit(const uint8_t* data, size_t len, uint8_t addr) {
   // start transmission
   int16_t state = startTransmit(data, len, addr);
   RADIOLIB_ASSERT(state);
@@ -175,7 +175,7 @@ void nRF24::clearPacketSentAction() {
   this->clearIrqAction();
 }
 
-int16_t nRF24::startTransmit(uint8_t* data, size_t len, uint8_t addr) {
+int16_t nRF24::startTransmit(const uint8_t* data, size_t len, uint8_t addr) {
   // suppress unused variable warning
   (void)addr;
 
@@ -205,7 +205,7 @@ int16_t nRF24::startTransmit(uint8_t* data, size_t len, uint8_t addr) {
   uint8_t buff[32];
   memset(buff, 0x00, 32);
   memcpy(buff, data, len);
-  SPIwriteTxPayload(data, len);
+  SPIwriteTxPayload(const_cast<uint8_t*>(data), len);
 
   // CE high to start transmitting
   this->mod->hal->digitalWrite(this->mod->getRst(), this->mod->hal->GpioLevelHigh);
diff --git a/src/modules/nRF24/nRF24.h b/src/modules/nRF24/nRF24.h
index 14d26209..428df70f 100644
--- a/src/modules/nRF24/nRF24.h
+++ b/src/modules/nRF24/nRF24.h
@@ -238,7 +238,7 @@ class nRF24: public PhysicalLayer {
       \param addr Dummy address parameter, to ensure PhysicalLayer compatibility.
       \returns \ref status_codes
     */
-    int16_t transmit(uint8_t* data, size_t len, uint8_t addr) override;
+    int16_t transmit(const uint8_t* data, size_t len, uint8_t addr) override;
 
     /*!
       \brief Blocking binary receive method.
@@ -305,7 +305,7 @@ class nRF24: public PhysicalLayer {
       \param addr Dummy address parameter, to ensure PhysicalLayer compatibility.
       \returns \ref status_codes
     */
-    int16_t startTransmit(uint8_t* data, size_t len, uint8_t addr) override;
+    int16_t startTransmit(const uint8_t* data, size_t len, uint8_t addr) override;
 
     /*!
       \brief Clean up after transmission is done.
diff --git a/src/protocols/PhysicalLayer/PhysicalLayer.cpp b/src/protocols/PhysicalLayer/PhysicalLayer.cpp
index f351cb47..dc97908b 100644
--- a/src/protocols/PhysicalLayer/PhysicalLayer.cpp
+++ b/src/protocols/PhysicalLayer/PhysicalLayer.cpp
@@ -53,7 +53,7 @@ int16_t PhysicalLayer::transmit(const char* str, uint8_t addr) {
   return(transmit((uint8_t*)str, strlen(str), addr));
 }
 
-int16_t PhysicalLayer::transmit(uint8_t* data, size_t len, uint8_t addr) {
+int16_t PhysicalLayer::transmit(const uint8_t* data, size_t len, uint8_t addr) {
   (void)data;
   (void)len;
   (void)addr;
@@ -150,7 +150,7 @@ int16_t PhysicalLayer::startTransmit(const char* str, uint8_t addr) {
   return(startTransmit((uint8_t*)str, strlen(str), addr));
 }
 
-int16_t PhysicalLayer::startTransmit(uint8_t* data, size_t len, uint8_t addr) {
+int16_t PhysicalLayer::startTransmit(const uint8_t* data, size_t len, uint8_t addr) {
   (void)data;
   (void)len;
   (void)addr;
diff --git a/src/protocols/PhysicalLayer/PhysicalLayer.h b/src/protocols/PhysicalLayer/PhysicalLayer.h
index a32997d3..ad53f622 100644
--- a/src/protocols/PhysicalLayer/PhysicalLayer.h
+++ b/src/protocols/PhysicalLayer/PhysicalLayer.h
@@ -98,7 +98,7 @@ class PhysicalLayer {
       \param addr Node address to transmit the packet to. Only used in FSK mode.
       \returns \ref status_codes
     */
-    virtual int16_t transmit(uint8_t* data, size_t len, uint8_t addr = 0);
+    virtual int16_t transmit(const uint8_t* data, size_t len, uint8_t addr = 0);
 
     #if defined(RADIOLIB_BUILD_ARDUINO)
     /*!
@@ -181,7 +181,7 @@ class PhysicalLayer {
       \param addr Node address to transmit the packet to. Only used in FSK mode.
       \returns \ref status_codes
     */
-    virtual int16_t startTransmit(uint8_t* data, size_t len, uint8_t addr = 0);
+    virtual int16_t startTransmit(const uint8_t* data, size_t len, uint8_t addr = 0);
 
     /*!
       \brief Clean up after transmission is done.