Further refinements of TWIBus

Marlin/Marlin_main.cpp

@@ -842,12 +842,7 @@ void servo_init() {
   }
 
   void i2c_on_request() {          // just send dummy data for now
-    static const char *msg = "Hello World!\n";
+    i2c.reply("Hello World!\n");
-    const char *adr = msg;
-    char c;
-    i2c.reset();
-    while (c = *adr++) i2c.addbyte(c);
-    i2c.send();
   }
 
 #endif

Marlin/twibus.cpp

@@ -42,38 +42,60 @@ void TWIBus::reset() {
   this->buffer[0] = 0x00;
 }
 
-void TWIBus::address(const uint8_t addr) {
+void TWIBus::address(const uint8_t adr) {
-  this->addr = addr;
+  this->addr = adr;
 
   #if ENABLED(DEBUG_TWIBUS)
-    debug(PSTR("address"), this->addr);
+    debug(PSTR("address"), adr);
   #endif
 }
 
 void TWIBus::addbyte(const char c) {
-  if (buffer_s >= sizeof(this->buffer)) return;
+  if (this->buffer_s >= COUNT(this->buffer)) return;
   this->buffer[this->buffer_s++] = c;
+  #if ENABLED(DEBUG_TWIBUS)
+    debug(PSTR("addbyte"), c);
+  #endif
+}
 
+void TWIBus::addbytes(char src[], uint8_t bytes) {
   #if ENABLED(DEBUG_TWIBUS)
-    debug(PSTR("addbyte"), this->buffer[this->buffer_s - 1]);
+    debug(PSTR("addbytes"), bytes);
   #endif
+  while (bytes--) this->addbyte(*src++);
+}
+
+void TWIBus::addstring(char str[]) {
+  #if ENABLED(DEBUG_TWIBUS)
+    debug(PSTR("addstring"), str);
+  #endif
+  while (char c = *str++) this->addbyte(c);
 }
 
 void TWIBus::send() {
   if (!this->addr) return;
 
   #if ENABLED(DEBUG_TWIBUS)
-    debug(PSTR("send()"));
+    debug(PSTR("send"), this->addr);
   #endif
 
   Wire.beginTransmission(this->addr);
   Wire.write(this->buffer, this->buffer_s);
   Wire.endTransmission();
 
-  // Reset the buffer after sending the data
   this->reset();
 }
 
+void TWIBus::echodata(uint8_t bytes, const char prefix[], uint8_t adr) {
+  SERIAL_ECHO_START;
+  serialprintPGM(prefix);
+  SERIAL_ECHOPAIR(": from:", adr);
+  SERIAL_ECHOPAIR(" bytes:", bytes);
+  SERIAL_ECHOPGM (" data:");
+  while (bytes-- && Wire.available()) SERIAL_CHAR(Wire.read());
+  SERIAL_EOL;
+}
+
 void TWIBus::reqbytes(const uint8_t bytes) {
   if (!this->addr) return;
 
@@ -82,34 +104,57 @@ void TWIBus::reqbytes(const uint8_t bytes) {
   #endif
 
   // requestFrom() is a blocking function
-  millis_t t = millis() + this->timeout;
   Wire.requestFrom(this->addr, bytes);
+
+  // Wait until all bytes arrive, or timeout
+  millis_t t = millis() + this->timeout;
   while (Wire.available() < bytes && PENDING(millis(), t)) { /*nada*/ }
 
-  this->relaydata(bytes);
+  // Simply echo the data to the bus
+  this->echodata(bytes, PSTR("i2c-reply"), this->addr);
+}
+
+#if I2C_SLAVE_ADDRESS > 0
 
-  // Reset the buffer after sending the data
+  void TWIBus::receive(uint8_t bytes) {
+    #if ENABLED(DEBUG_TWIBUS)
+      debug(PSTR("receive"), bytes);
+    #endif
+    this->echodata(bytes, PSTR("i2c-receive"), 0);
+  }
+
+  void TWIBus::reply(char str[]/*=NULL*/) {
+    #if ENABLED(DEBUG_TWIBUS)
+      debug(PSTR("reply"), str);
+    #endif
+
+    if (str) {
       this->reset();
-}
+      this->addstring(str);
+    }
 
-void TWIBus::relaydata(uint8_t bytes) {
+    Wire.write(this->buffer, this->buffer_s);
-  SERIAL_ECHO_START;
+
-  SERIAL_ECHOPAIR("i2c-reply: from:", this->addr);
+    this->reset();
-  SERIAL_ECHOPAIR(" bytes:", bytes);
+  }
-  SERIAL_ECHOPGM (" data:");
+
-  while (bytes-- && Wire.available()) SERIAL_CHAR(Wire.read());
+#endif
-  SERIAL_EOL;
-}
 
 #if ENABLED(DEBUG_TWIBUS)
 
-  void TWIBus::debug(const char func[], int32_t val/*=-1*/) {
+  void TWIBus::prefix(const char func[]) {
-    if (DEBUGGING(INFO)) {
     SERIAL_ECHOPGM("TWIBus::");
     serialprintPGM(func);
-      if (val >= 0) SERIAL_ECHOPAIR(": ", val);
+    SERIAL_ECHOPGM(": ");
-      SERIAL_EOL;
+  }
+  void TWIBus::debug(const char func[], uint32_t adr) {
+    if (DEBUGGING(INFO)) { prefix(func); SERIAL_ECHOLN(adr); }
+  }
+  void TWIBus::debug(const char func[], char c) {
+    if (DEBUGGING(INFO)) { prefix(func); SERIAL_ECHOLN(c); }
   }
+  void TWIBus::debug(const char func[], char str[]) {
+    if (DEBUGGING(INFO)) { prefix(func); SERIAL_ECHOLN(str); }
   }
 
 #endif

Marlin/twibus.h

@@ -62,7 +62,7 @@ class TWIBus {
 
     /**
      * @brief Number of bytes on buffer
-     * @description Number of bytes in the buffer waiting to be flushed to the bus.
+     * @description Number of bytes in the buffer waiting to be flushed to the bus
      */
     uint8_t buffer_s = 0;
 
@@ -94,7 +94,7 @@ class TWIBus {
 
     /**
      * @brief Send the buffer data to the bus
-     * @details Flush the buffer to the bus at the target address.
+     * @details Flush the buffer to the target address
      */
     void send();
 
@@ -107,45 +107,57 @@ class TWIBus {
      */
     void addbyte(const char c);
 
+    /**
+     * @brief Add some bytes to the buffer
+     * @details Add bytes to the end of the buffer.
+     *          Concatenates at the buffer size.
+     *
+     * @param src source data address
+     * @param bytes the number of bytes to add
+     */
+    void addbytes(char src[], uint8_t bytes);
+
+    /**
+     * @brief Add a null-terminated string to the buffer
+     * @details Add bytes to the end of the buffer up to a nul.
+     *          Concatenates at the buffer size.
+     *
+     * @param str source string address
+     */
+    void addstring(char str[]);
+
     /**
      * @brief Set the target slave address
-     * @details The target slave address for sending the full packet.
+     * @details The target slave address for sending the full packet
      *
-     * @param addr 7-bit integer address
+     * @param adr 7-bit integer address
      */
-    void address(const uint8_t addr);
+    void address(const uint8_t adr);
 
     /**
-     * @brief Request data from the slave device
+     * @brief Echo data on the bus to serial
-     * @details Request a number of bytes from a slave device.
+     * @details Echo some number of bytes from the bus
-     *          This implementation simply sends the data to serial
+     *          to serial in a parser-friendly format.
-     *          in a parser-friendly format.
      *
      * @param bytes the number of bytes to request
      */
-    void reqbytes(const uint8_t bytes);
+    static void echodata(uint8_t bytes, const char prefix[], uint8_t adr);
 
     /**
-     * @brief Relay data from the slave device to serial
+     * @brief Request data from the slave device
-     * @details Relay a number of bytes from the bus to
+     * @details Request a number of bytes from a slave device.
-     *          serial in a parser-friendly format.
+     *          This implementation simply sends the data to serial
+     *          in a parser-friendly format.
      *
      * @param bytes the number of bytes to request
      */
-    void relaydata(uint8_t bytes);
+    void reqbytes(const uint8_t bytes);
 
     #if I2C_SLAVE_ADDRESS > 0
 
-      /**
-       * @brief Receive bytes (passively)
-       * @details Receive bytes sent to our slave address.
-       *          and simply echo them to serial.
-       */
-      inline void receive(uint8_t bytes) { relaydata(bytes); }
-
       /**
        * @brief Register a slave receive handler
-       * @details Set a handler to receive data addressed to us.
+       * @details Set a handler to receive data addressed to us
        *
        * @param handler A function to handle receiving bytes
        */
@@ -153,12 +165,25 @@ class TWIBus {
 
       /**
        * @brief Register a slave request handler
-       * @details Set a handler to send data requested from us.
+       * @details Set a handler to send data requested from us
        *
        * @param handler A function to handle receiving bytes
        */
       inline void onRequest(const twiRequestFunc_t handler) { Wire.onRequest(handler); }
 
+      /**
+       * @brief Default handler to receive
+       * @details Receive bytes sent to our slave address
+       *          and simply echo them to serial.
+       */
+      void receive(uint8_t bytes);
+
+      /**
+       * @brief Send a reply to the bus
+       * @details Send the buffer and clear it.
+       */
+      void reply(char str[]=NULL);
+
     #endif
 
     #if ENABLED(DEBUG_TWIBUS)
@@ -167,7 +192,11 @@ class TWIBus {
        * @brief Prints a debug message
        * @details Prints a simple debug message "TWIBus::function: value"
        */
-      static void debug(const char func[], int32_t val = -1);
+      static void prefix(const char func[]);
+      static void debug(const char func[], uint32_t adr);
+      static void debug(const char func[], char c);
+      static void debug(const char func[], char adr[]);
+      static inline void debug(const char func[], uint8_t v) { debug(func, (uint32_t)v); }
 
     #endif
 };