I2C multi instances: Remove static qualifier on TwoWire attributes

I2C buffers, as well as some other attributes of the TwoWire class,
should not be static (shared between instances),
otherwise multi instance I2C doesn't work properly.
For example when MCU is master on one instance and slave on the other,
Slave reception under interruption can happen in the middle of master transmission,
and there is conflict on the shared resources.

fixes #699

Author: ABOSTM

libraries/Wire/src/Wire.cpp

@@ -27,22 +27,6 @@ extern "C" {
 
 #include "Wire.h"
 
-// Initialize Class Variables //////////////////////////////////////////////////
-uint8_t *TwoWire::rxBuffer = nullptr;
-uint8_t TwoWire::rxBufferAllocated = 0;
-uint8_t TwoWire::rxBufferIndex = 0;
-uint8_t TwoWire::rxBufferLength = 0;
-
-uint8_t TwoWire::txAddress = 0;
-uint8_t *TwoWire::txBuffer = nullptr;
-uint8_t TwoWire::txBufferAllocated = 0;
-uint8_t TwoWire::txBufferIndex = 0;
-uint8_t TwoWire::txBufferLength = 0;
-
-uint8_t TwoWire::transmitting = 0;
-void (*TwoWire::user_onRequest)(void);
-void (*TwoWire::user_onReceive)(int);
-
 // Constructors ////////////////////////////////////////////////////////////////
 
 TwoWire::TwoWire()
@@ -81,6 +65,13 @@ void TwoWire::begin(uint8_t address, bool generalCall)
   txBufferLength = 0;
   resetTxBuffer();
 
+  rxBuffer = nullptr;
+  rxBufferAllocated = 0;
+  txAddress = 0;
+  txBuffer = nullptr;
+  txBufferAllocated = 0;
+  _i2c.__this = (void *)this;
+  user_onRequest = NULL;
   transmitting = 0;
 
   ownAddress = address << 1;
@@ -403,44 +394,48 @@ void TwoWire::flush(void)
 }
 
 // behind the scenes function that is called when data is received
-void TwoWire::onReceiveService(uint8_t *inBytes, int numBytes)
+void TwoWire::onReceiveService(i2c_t *obj, uint8_t *inBytes, int numBytes)
 {
+  TwoWire *TW = (TwoWire *)(obj->__this);
+
   // don't bother if user hasn't registered a callback
-  if (user_onReceive) {
+  if (TW->user_onReceive) {
     // don't bother if rx buffer is in use by a master requestFrom() op
     // i know this drops data, but it allows for slight stupidity
     // meaning, they may not have read all the master requestFrom() data yet
-    if (rxBufferIndex >= rxBufferLength) {
+    if (TW->rxBufferIndex >= TW->rxBufferLength) {
 
-      allocateRxBuffer(numBytes);
+      TW->allocateRxBuffer(numBytes);
       // error if no memory block available to allocate the buffer
-      if (rxBuffer == nullptr) {
+      if (TW->rxBuffer == nullptr) {
         Error_Handler();
       }
 
       // copy twi rx buffer into local read buffer
       // this enables new reads to happen in parallel
-      memcpy(rxBuffer, inBytes, numBytes);
+      memcpy(TW->rxBuffer, inBytes, numBytes);
       // set rx iterator vars
-      rxBufferIndex = 0;
-      rxBufferLength = numBytes;
+      TW->rxBufferIndex = 0;
+      TW->rxBufferLength = numBytes;
       // alert user program
-      user_onReceive(numBytes);
+      TW->user_onReceive(numBytes);
     }
   }
 }
 
 // behind the scenes function that is called when data is requested
-void TwoWire::onRequestService(void)
+void TwoWire::onRequestService(i2c_t *obj)
 {
+  TwoWire *TW = (TwoWire *)(obj->__this);
+
   // don't bother if user hasn't registered a callback
-  if (user_onRequest) {
+  if (TW->user_onRequest) {
     // reset tx buffer iterator vars
     // !!! this will kill any pending pre-master sendTo() activity
-    txBufferIndex = 0;
-    txBufferLength = 0;
+    TW->txBufferIndex = 0;
+    TW->txBufferLength = 0;
     // alert user program
-    user_onRequest();
+    TW->user_onRequest();
   }
 }
 

libraries/Wire/src/Wire.h

@@ -37,28 +37,28 @@ extern "C" {
 
 class TwoWire : public Stream {
   private:
-    static uint8_t *rxBuffer;
-    static uint8_t rxBufferAllocated;
-    static uint8_t rxBufferIndex;
-    static uint8_t rxBufferLength;
+    uint8_t *rxBuffer;
+    uint8_t rxBufferAllocated;
+    uint8_t rxBufferIndex;
+    uint8_t rxBufferLength;
 
-    static uint8_t txAddress;
-    static uint8_t *txBuffer;
-    static uint8_t txBufferAllocated;
-    static uint8_t txBufferIndex;
-    static uint8_t txBufferLength;
+    uint8_t txAddress;
+    uint8_t *txBuffer;
+    uint8_t txBufferAllocated;
+    uint8_t txBufferIndex;
+    uint8_t txBufferLength;
 
-    static uint8_t transmitting;
+    uint8_t transmitting;
 
     uint8_t ownAddress;
     i2c_t _i2c;
 
-    static void (*user_onRequest)(void);
-    static void (*user_onReceive)(int);
-    static void onRequestService(void);
-    static void onReceiveService(uint8_t *, int);
+    void (*user_onRequest)(void);
+    void (*user_onReceive)(int);
+    static void onRequestService(i2c_t *);
+    static void onReceiveService(i2c_t *, uint8_t *, int);
 
-    static void allocateRxBuffer(size_t length);
+    void allocateRxBuffer(size_t length);
     void allocateTxBuffer(size_t length);
 
     void resetRxBuffer(void);

libraries/Wire/src/utility/twi.c

@@ -948,7 +948,7 @@ i2c_t *get_i2c_obj(I2C_HandleTypeDef *hi2c)
   * @param  function: callback function to use
   * @retval None
   */
-void i2c_attachSlaveRxEvent(i2c_t *obj, void (*function)(uint8_t *, int))
+void i2c_attachSlaveRxEvent(i2c_t *obj, void (*function)(i2c_t *, uint8_t *, int))
 {
   if ((obj != NULL) && (function != NULL)) {
     obj->i2c_onSlaveReceive = function;
@@ -961,7 +961,7 @@ void i2c_attachSlaveRxEvent(i2c_t *obj, void (*function)(uint8_t *, int))
   * @param  function: callback function to use
   * @retval None
   */
-void i2c_attachSlaveTxEvent(i2c_t *obj, void (*function)(void))
+void i2c_attachSlaveTxEvent(i2c_t *obj, void (*function)(i2c_t *))
 {
   if ((obj != NULL) && (function != NULL)) {
     obj->i2c_onSlaveTransmit = function;
@@ -986,7 +986,7 @@ void HAL_I2C_AddrCallback(I2C_HandleTypeDef *hi2c, uint8_t TransferDirection, ui
       obj->slaveMode = SLAVE_MODE_TRANSMIT;
 
       if (obj->i2c_onSlaveTransmit != NULL) {
-        obj->i2c_onSlaveTransmit();
+        obj->i2c_onSlaveTransmit(obj);
       }
 #if defined(STM32F0xx) || defined(STM32F1xx) || defined(STM32F2xx) || defined(STM32F3xx) ||\
     defined(STM32F4xx) || defined(STM32L0xx) || defined(STM32L1xx) || defined(STM32MP1xx)
@@ -1026,7 +1026,7 @@ void HAL_I2C_ListenCpltCallback(I2C_HandleTypeDef *hi2c)
   /*  Previous master transaction now ended, so inform upper layer if needed
    *  then prepare for listening to next request */
   if ((obj->slaveMode == SLAVE_MODE_RECEIVE) && (obj->slaveRxNbData != 0)) {
-    obj->i2c_onSlaveReceive((uint8_t *) obj->i2cTxRxBuffer, obj->slaveRxNbData);
+    obj->i2c_onSlaveReceive(obj, (uint8_t *) obj->i2cTxRxBuffer, obj->slaveRxNbData);
   }
   obj->slaveMode = SLAVE_MODE_LISTEN;
   obj->slaveRxNbData = 0;

libraries/Wire/src/utility/twi.h

@@ -99,15 +99,16 @@ struct i2c_s {
      */
   I2C_TypeDef  *i2c;
   I2C_HandleTypeDef handle;
+  void *__this;
   PinName sda;
   PinName scl;
   IRQn_Type irq;
 #if !defined(STM32F0xx) && !defined(STM32G0xx) && !defined(STM32L0xx)
   IRQn_Type irqER;
 #endif /* !STM32F0xx && !STM32G0xx && !STM32L0xx */
   volatile int slaveRxNbData; // Number of accumulated bytes received in Slave mode
-  void (*i2c_onSlaveReceive)(uint8_t *, int);
-  void (*i2c_onSlaveTransmit)(void);
+  void (*i2c_onSlaveReceive)(i2c_t *, uint8_t *, int);
+  void (*i2c_onSlaveTransmit)(i2c_t *);
   volatile uint8_t i2cTxRxBuffer[I2C_TXRX_BUFFER_SIZE];
   volatile uint8_t i2cTxRxBufferSize;
   volatile uint8_t slaveMode;
@@ -138,8 +139,8 @@ i2c_status_e i2c_master_read(i2c_t *obj, uint8_t dev_address, uint8_t *data, uin
 
 i2c_status_e i2c_IsDeviceReady(i2c_t *obj, uint8_t devAddr, uint32_t trials);
 
-void i2c_attachSlaveRxEvent(i2c_t *obj, void (*function)(uint8_t *, int));
-void i2c_attachSlaveTxEvent(i2c_t *obj, void (*function)(void));
+void i2c_attachSlaveRxEvent(i2c_t *obj, void (*function)(i2c_t *, uint8_t *, int));
+void i2c_attachSlaveTxEvent(i2c_t *obj, void (*function)(i2c_t *));
 
 #ifdef __cplusplus
 }