[CC1101] FIFO Refills to transmit packets up to 255 bytes (#1404)

* Update CC1101.h

Add Max packet size for FIFO Refills

* Define FIFO Size, Max packet Length for FIFO refills

* FIFO REFILL

- Go through FSTXON State
- Check MARCSTATE to ensure ready to tx
- Initial FIFO fill
- Check FIFO bytes twice in accordance with errata
- Refill FIFO
- Check MARCSTATE is idle before returning

* Fix typos

* Fix another typo

* min -> std::min per build check

* Revert std::min back to min

* Use RADIOLIB_MIN Macro instead of min

* Move MARC State check for Idle to finishTransmit function

Change allows startTransmit to stop blocking once the last bytes are added to the FIFO

* Add timeouts for both MARC state checks

* Fix typo

* No interrupt for packets bigger than 64 bytes

* Initialize state as RADIOLIB_ERR_NONE if avoiding ISR

* Update example with packet size and discussion link

* Update example with new packet size and discussion link

* Update example, clarify blocking on greater than 64 bytes link discussion

* Update doxygen comments for 255 byte limit, limitations and discussion link

examples/CC1101/CC1101_Transmit_Address/CC1101_Transmit_Address.ino

@@ -82,10 +82,11 @@ void setup() {
 void loop() {
   Serial.print(F("[CC1101] Transmitting packet ... "));
 
-  // you can transmit C-string or Arduino string up to 64 characters long
+  // you can transmit C-string or Arduino string up to 255 characters long
   int state = radio.transmit("Hello World!");
 
-  // you can also transmit byte array up to 64 bytes long
+  // you can also transmit byte array up to 255 bytes long
+  // With some limitations see here: https://github.com/jgromes/RadioLib/discussions/1138
   /*
     byte byteArr[] = {0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF};
     int state = radio.transmit(byteArr, 8);

examples/CC1101/CC1101_Transmit_Blocking/CC1101_Transmit_Blocking.ino

@@ -2,7 +2,7 @@
   RadioLib CC1101 Blocking Transmit Example
 
   This example transmits packets using CC1101 FSK radio module.
-  Each packet contains up to 64 bytes of data, in the form of:
+  Each packet contains up to 255 bytes of data with some limitations (https://github.com/jgromes/RadioLib/discussions/1138), in the form of:
   - Arduino String
   - null-terminated char array (C-string)
   - arbitrary binary data (byte array)
@@ -57,11 +57,11 @@ int count = 0;
 void loop() {
   Serial.print(F("[CC1101] Transmitting packet ... "));
 
-  // you can transmit C-string or Arduino string up to 64 characters long
+  // you can transmit C-string or Arduino string up to 255 characters long
   String str = "Hello World! #" + String(count++);
   int state = radio.transmit(str);
 
-  // you can also transmit byte array up to 64 bytes long
+  // you can also transmit byte array up to 255 bytes long with some limitations; https://github.com/jgromes/RadioLib/discussions/1138
   /*
     byte byteArr[] = {0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF};
     int state = radio.transmit(byteArr, 8);
@@ -72,7 +72,7 @@ void loop() {
     Serial.println(F("success!"));
 
   } else if (state == RADIOLIB_ERR_PACKET_TOO_LONG) {
-    // the supplied packet was longer than 64 bytes
+    // the supplied packet was longer than 255 bytes
     Serial.println(F("too long!"));
 
   } else {

examples/CC1101/CC1101_Transmit_Interrupt/CC1101_Transmit_Interrupt.ino

@@ -3,7 +3,7 @@
 
   This example transmits packets using CC1101 FSK radio module.
   Once a packet is transmitted, an interrupt is triggered.
-  Each packet contains up to 64 bytes of data, in the form of:
+  Each packet contains up to 255 bytes of data with some limitations (https://github.com/jgromes/RadioLib/discussions/1138), in the form of:
   - Arduino String
   - null-terminated char array (C-string)
   - arbitrary binary data (byte array)
@@ -73,10 +73,12 @@ void setup() {
   Serial.print(F("[CC1101] Sending first packet ... "));
 
   // you can transmit C-string or Arduino string up to
-  // 64 characters long
+  // 255 characters long
   transmissionState = radio.startTransmit("Hello World!");
 
-  // you can also transmit byte array up to 64 bytes long
+  // you can also transmit byte array up to 255 bytes long
+  // When transmitting more than 64 bytes startTransmit blocks to refill the FIFO.
+  // Blocking ceases once the last bytes have been placed in the FIFO
   /*
     byte byteArr[] = {0x01, 0x23, 0x45, 0x56,
                       0x78, 0xAB, 0xCD, 0xEF};
@@ -119,11 +121,11 @@ void loop() {
     Serial.print(F("[CC1101] Sending another packet ... "));
 
     // you can transmit C-string or Arduino string up to
-    // 64 characters long
+    // 255 characters long
     String str = "Hello World! #" + String(count++);
     transmissionState = radio.startTransmit(str);
 
-    // you can also transmit byte array up to 64 bytes long
+    // you can also transmit byte array up to 255 bytes long with limitations https://github.com/jgromes/RadioLib/discussions/1138
     /*
       byte byteArr[] = {0x01, 0x23, 0x45, 0x67,
                         0x89, 0xAB, 0xCD, 0xEF};

src/modules/CC1101/CC1101.cpp

@@ -236,23 +236,49 @@ int16_t CC1101::startTransmit(const uint8_t* data, size_t len, uint8_t addr) {
   // flush Tx FIFO
   SPIsendCommand(RADIOLIB_CC1101_CMD_FLUSH_TX);
 
-  // set GDO0 mapping
-  int16_t state = SPIsetRegValue(RADIOLIB_CC1101_REG_IOCFG2, RADIOLIB_CC1101_GDOX_SYNC_WORD_SENT_OR_PKT_RECEIVED, 5, 0);
-  RADIOLIB_ASSERT(state);
+  // Turn on freq oscilator
+  SPIsendCommand(RADIOLIB_CC1101_CMD_FSTXON);
+
+  // Check MARCSTATE and wait until ready to tx
+  // 724us is the longest time for calibrate per datasheet
+  RadioLibTime_t start = this->mod->hal->micros();
+  while(SPIgetRegValue(RADIOLIB_CC1101_REG_MARCSTATE, 4, 0) != 0x12) {
+    if(this->mod->hal->micros() - start > 724) {
+      standby();
+      return(RADIOLIB_ERR_TX_TIMEOUT);
+    }
+  }
+
+  // set GDO0 mapping only if we aren't refilling the FIFO
+  int16_t state = RADIOLIB_ERR_NONE;
+  if(len <= RADIOLIB_CC1101_FIFO_SIZE) {
+    state = SPIsetRegValue(RADIOLIB_CC1101_REG_IOCFG2, RADIOLIB_CC1101_GDOX_SYNC_WORD_SENT_OR_PKT_RECEIVED, 5, 0);
+    RADIOLIB_ASSERT(state);
+  }
+
+  // data put on FIFO
+  uint8_t dataSent = 0;
 
   // optionally write packet length
   if(this->packetLengthConfig == RADIOLIB_CC1101_LENGTH_CONFIG_VARIABLE) {
+    if (len > RADIOLIB_CC1101_MAX_PACKET_LENGTH - 1) {
+        return(RADIOLIB_ERR_PACKET_TOO_LONG);
+    }
     SPIwriteRegister(RADIOLIB_CC1101_REG_FIFO, len);
+    dataSent+= 1;
   }
 
   // check address filtering
   uint8_t filter = SPIgetRegValue(RADIOLIB_CC1101_REG_PKTCTRL1, 1, 0);
   if(filter != RADIOLIB_CC1101_ADR_CHK_NONE) {
     SPIwriteRegister(RADIOLIB_CC1101_REG_FIFO, addr);
+    dataSent += 1;
   }
 
   // fill the FIFO
-  SPIwriteRegisterBurst(RADIOLIB_CC1101_REG_FIFO, const_cast<uint8_t*>(data), len);
+  uint8_t initialWrite = RADIOLIB_MIN((uint8_t)len, (uint8_t)(RADIOLIB_CC1101_FIFO_SIZE - dataSent));
+  SPIwriteRegisterBurst(RADIOLIB_CC1101_REG_FIFO, const_cast<uint8_t*>(data), initialWrite);
+  dataSent += initialWrite;
 
   // set RF switch (if present)
   this->mod->setRfSwitchState(Module::MODE_TX);
@@ -260,11 +286,40 @@ int16_t CC1101::startTransmit(const uint8_t* data, size_t len, uint8_t addr) {
   // set mode to transmit
   SPIsendCommand(RADIOLIB_CC1101_CMD_TX);
 
+  // Keep feeding the FIFO until the packet is done
+  while (dataSent < len) {
+    uint8_t fifoBytes = 0;
+    uint8_t prevFifobytes = 0;
+
+    // Check number of bytes on FIFO twice due to the CC1101 errata. Block until two reads are equal.
+    do{
+      fifoBytes = SPIgetRegValue(RADIOLIB_CC1101_REG_TXBYTES, 6, 0);
+      prevFifobytes = SPIgetRegValue(RADIOLIB_CC1101_REG_TXBYTES, 6, 0);
+    } while (fifoBytes != prevFifobytes);
+
+    //If there is room add more data to the FIFO
+    if (fifoBytes < RADIOLIB_CC1101_FIFO_SIZE) {
+        uint8_t bytesToWrite = RADIOLIB_MIN((uint8_t)(RADIOLIB_CC1101_FIFO_SIZE - fifoBytes), (uint8_t)(len - dataSent));
+        SPIwriteRegisterBurst(RADIOLIB_CC1101_REG_FIFO, const_cast<uint8_t*>(&data[dataSent]), bytesToWrite);
+        dataSent += bytesToWrite;
+    }
+  }
   return(state);
 }
 
 int16_t CC1101::finishTransmit() {
   // set mode to standby to disable transmitter/RF switch
+  
+  // Check MARCSTATE for Idle to let anything in the FIFO empty
+  // Timeout is 2x FIFO transmit time
+  RadioLibTime_t timeout = (1.0f/(this->bitRate))*(RADIOLIB_CC1101_FIFO_SIZE*2.0f);
+  RadioLibTime_t start = this->mod->hal->millis();
+  while(SPIgetRegValue(RADIOLIB_CC1101_REG_MARCSTATE, 4, 0) != 0x01) {
+    if(this->mod->hal->millis() - start > timeout) {
+      return(RADIOLIB_ERR_TX_TIMEOUT);
+    }
+  }
+  
   int16_t state = standby();
   RADIOLIB_ASSERT(state);
 

src/modules/CC1101/CC1101.h

@@ -8,7 +8,8 @@
 
 // CC1101 physical layer properties
 #define RADIOLIB_CC1101_FREQUENCY_STEP_SIZE                     396.7285156
-#define RADIOLIB_CC1101_MAX_PACKET_LENGTH                       64
+#define RADIOLIB_CC1101_MAX_PACKET_LENGTH                       255
+#define RADIOLIB_CC1101_FIFO_SIZE                               64
 #define RADIOLIB_CC1101_CRYSTAL_FREQ                            26.0f
 #define RADIOLIB_CC1101_DIV_EXPONENT                            16
 
@@ -701,7 +702,10 @@ class CC1101: public PhysicalLayer {
     void clearPacketSentAction() override;
 
     /*!
-      \brief Interrupt-driven binary transmit method.
+      \brief Interrupt-driven binary transmit method for packets less than 64 bytes.
+      Method blocks for packets longer than 64 bytes up to a 255 byte limit, until 
+      the last bytes are placed in the FIFO. Some limitations and issues apply; see discussion: 
+      https://github.com/jgromes/RadioLib/discussions/1138
       Overloads for string-based transmissions are implemented in PhysicalLayer.
       \param data Binary data to be sent.
       \param len Number of bytes to send.