Split software I2C code into Master-only and Master-or-Slave parts, enabling multiple instances of TwoWire in master-only role

cores/esp8266/core_esp8266_si2c.cpp

@@ -57,17 +57,12 @@ static inline __attribute__((always_inline)) bool SCL_READ(const int twi_scl)
  return (GPI & (1 << twi_scl)) != 0;
 }
 
-
 // Implement as a class to reduce code size by allowing access to many global variables with a single base pointer
-class Twi
+// Derived from TwiMaster which can be instantied multiple times
+class TwiMasterOrSlave : public TwiMaster
 {
 private:
- unsigned int preferred_si2c_clock = 100000;
- uint32_t twi_dcount = 18;
- unsigned char twi_sda = 0;
- unsigned char twi_scl = 0;
  unsigned char twi_addr = 0;
- uint32_t twi_clockStretchLimit = 0;
 
  // These are int-wide, even though they could all fit in a byte, to reduce code size and avoid any potential
  // issues about RmW on packed bytes. The int-wide variations of asm instructions are smaller than the equivalent
@@ -93,8 +88,9 @@ class Twi
  uint8_t twi_rxBuffer[TWI_BUFFER_LENGTH];
  volatile int twi_rxBufferIndex = 0;
 
- void (*twi_onSlaveTransmit)(void);
- void (*twi_onSlaveReceive)(uint8_t*, size_t);
+ void* twi_SlaveTargetObject;
+ void (*twi_onSlaveTransmit)(void*);
+ void (*twi_onSlaveReceive)(uint8_t*, size_t, void*);
 
  // ETS queue/timer interfaces
  enum { EVENTTASK_QUEUE_SIZE = 1, EVENTTASK_QUEUE_PRIO = 2 };
@@ -108,59 +104,46 @@ class Twi
  static void eventTask(ETSEvent *e);
  static void IRAM_ATTR onTimer(void *unused);
 
- // Allow not linking in the slave code if there is no call to setAddress
+ // Allow not linking in the slave code if there is no call to enableSlave
  bool _slaveEnabled = false;
 
  // Internal use functions
- void IRAM_ATTR busywait(unsigned int v);
- bool write_start(void);
- bool write_stop(void);
- bool write_bit(bool bit);
- bool read_bit(void);
- bool write_byte(unsigned char byte);
- unsigned char read_byte(bool nack);
  void IRAM_ATTR onTwipEvent(uint8_t status);
 
- // Handle the case where a slave needs to stretch the clock with a time-limited busy wait
- inline void WAIT_CLOCK_STRETCH()
- {
- esp8266::polledTimeout::oneShotFastUs timeout(twi_clockStretchLimit);
- esp8266::polledTimeout::periodicFastUs yieldTimeout(5000);
- while (!timeout && !SCL_READ(twi_scl)) // outer loop is stretch duration up to stretch limit
- {
- if (yieldTimeout) // inner loop yields every 5ms
- {
- yield();
- }
- }
- }
-
- // Generate a clock "valley" (at the end of a segment, just before a repeated start)
- void twi_scl_valley(void);
-
 public:
- void setClock(unsigned int freq);
- void setClockStretchLimit(uint32_t limit);
+ // custom version
  void init(unsigned char sda, unsigned char scl);
+
  void setAddress(uint8_t address);
- unsigned char writeTo(unsigned char address, unsigned char * buf, unsigned int len, unsigned char sendStop);
- unsigned char readFrom(unsigned char address, unsigned char* buf, unsigned int len, unsigned char sendStop);
- uint8_t status();
  uint8_t transmit(const uint8_t* data, uint8_t length);
- void attachSlaveRxEvent(void (*function)(uint8_t*, size_t));
- void attachSlaveTxEvent(void (*function)(void));
+ void attachSlaveRxEvent(void (*function)(uint8_t*, size_t, void*));
+ void attachSlaveTxEvent(void (*function)(void*));
  void IRAM_ATTR reply(uint8_t ack);
  void IRAM_ATTR releaseBus(void);
- void enableSlave();
+ void enableSlave(void* targetObject);
 };
 
-static Twi twi;
+static TwiMasterOrSlave twi;
+TwiMaster& twiMasterSingleton = twi;
 
 #ifndef FCPU80
 #define FCPU80 80000000L
 #endif
 
-void Twi::setClock(unsigned int freq)
+inline void TwiMaster::WAIT_CLOCK_STRETCH()
+{
+ esp8266::polledTimeout::oneShotFastUs timeout(twi_clockStretchLimit);
+ esp8266::polledTimeout::periodicFastUs yieldTimeout(5000);
+ while (!timeout && !SCL_READ(twi_scl)) // outer loop is stretch duration up to stretch limit
+ {
+ if (yieldTimeout) // inner loop yields every 5ms
+ {
+ yield();
+ }
+ }
+}
+
+void TwiMaster::setClock(unsigned int freq)
 {
  if (freq < 1000) // minimum freq 1000Hz to minimize slave timeouts and WDT resets
  {
@@ -190,14 +173,24 @@ void Twi::setClock(unsigned int freq)
 #endif
 }
 
-void Twi::setClockStretchLimit(uint32_t limit)
+void TwiMaster::setClockStretchLimit(uint32_t limit)
 {
  twi_clockStretchLimit = limit;
 }
 
 
 
-void Twi::init(unsigned char sda, unsigned char scl)
+void TwiMaster::init(unsigned char sda, unsigned char scl)
+{
+ twi_sda = sda;
+ twi_scl = scl;
+ pinMode(twi_sda, INPUT_PULLUP);
+ pinMode(twi_scl, INPUT_PULLUP);
+ twi_setClock(preferred_si2c_clock);
+ twi_setClockStretchLimit(150000L); // default value is 150 mS
+}
+
+void TwiMasterOrSlave::init(unsigned char sda, unsigned char scl)
 {
  // set timer function
  ets_timer_setfn(&timer, onTimer, NULL);
@@ -213,32 +206,33 @@ void Twi::init(unsigned char sda, unsigned char scl)
  twi_setClockStretchLimit(150000L); // default value is 150 mS
 }
 
-void Twi::setAddress(uint8_t address)
+void TwiMasterOrSlave::setAddress(uint8_t address)
 {
  // set twi slave address (skip over R/W bit)
  twi_addr = address << 1;
 }
 
-void Twi::enableSlave()
+void TwiMasterOrSlave::enableSlave(void* targetObject)
 {
  if (!_slaveEnabled)
  {
+ twi_SlaveTargetObject = targetObject;
  attachInterrupt(twi_scl, onSclChange, CHANGE);
  attachInterrupt(twi_sda, onSdaChange, CHANGE);
  _slaveEnabled = true;
  }
 }
 
-void IRAM_ATTR Twi::busywait(unsigned int v)
+void IRAM_ATTR TwiMaster::busywait(unsigned int v)
 {
  unsigned int i;
  for (i = 0; i < v; i++) // loop time is 5 machine cycles: 31.25ns @ 160MHz, 62.5ns @ 80MHz
  {
- __asm__ __volatile__("nop"); // minimum element to keep GCC from optimizing this function out.
+ asm("nop"); // minimum element to keep GCC from optimizing this function out.
  }
 }
 
-bool Twi::write_start(void)
+bool TwiMaster::write_start(void)
 {
  SCL_HIGH(twi_scl);
  SDA_HIGH(twi_sda);
@@ -252,7 +246,7 @@ bool Twi::write_start(void)
  return true;
 }
 
-bool Twi::write_stop(void)
+bool TwiMaster::write_stop(void)
 {
  SCL_LOW(twi_scl);
  SDA_LOW(twi_sda);
@@ -265,7 +259,7 @@ bool Twi::write_stop(void)
  return true;
 }
 
-bool Twi::write_bit(bool bit)
+bool TwiMaster::write_bit(bool bit)
 {
  SCL_LOW(twi_scl);
  if (bit)
@@ -283,7 +277,7 @@ bool Twi::write_bit(bool bit)
  return true;
 }
 
-bool Twi::read_bit(void)
+bool TwiMaster::read_bit(void)
 {
  SCL_LOW(twi_scl);
  SDA_HIGH(twi_sda);
@@ -295,7 +289,7 @@ bool Twi::read_bit(void)
  return bit;
 }
 
-bool Twi::write_byte(unsigned char byte)
+bool TwiMaster::write_byte(unsigned char byte)
 {
  unsigned char bit;
  for (bit = 0; bit < 8; bit++)
@@ -306,7 +300,7 @@ bool Twi::write_byte(unsigned char byte)
  return !read_bit();//NACK/ACK
 }
 
-unsigned char Twi::read_byte(bool nack)
+unsigned char TwiMaster::read_byte(bool nack)
 {
  unsigned char byte = 0;
  unsigned char bit;
@@ -318,7 +312,7 @@ unsigned char Twi::read_byte(bool nack)
  return byte;
 }
 
-unsigned char Twi::writeTo(unsigned char address, unsigned char * buf, unsigned int len, unsigned char sendStop)
+unsigned char TwiMaster::writeTo(unsigned char address, unsigned char * buf, unsigned int len, unsigned char sendStop)
 {
  unsigned int i;
  if (!write_start())
@@ -363,7 +357,7 @@ unsigned char Twi::writeTo(unsigned char address, unsigned char * buf, unsigned
  return 0;
 }
 
-unsigned char Twi::readFrom(unsigned char address, unsigned char* buf, unsigned int len, unsigned char sendStop)
+unsigned char TwiMaster::readFrom(unsigned char address, unsigned char* buf, unsigned int len, unsigned char sendStop)
 {
  unsigned int i;
  if (!write_start())
@@ -402,15 +396,15 @@ unsigned char Twi::readFrom(unsigned char address, unsigned char* buf, unsigned
  return 0;
 }
 
-void Twi::twi_scl_valley(void)
+void TwiMaster::twi_scl_valley(void)
 {
  SCL_LOW(twi_scl);
  busywait(twi_dcount);
  SCL_HIGH(twi_scl);
  WAIT_CLOCK_STRETCH();
 }
 
-uint8_t Twi::status()
+uint8_t TwiMaster::status()
 {
  WAIT_CLOCK_STRETCH(); // wait for a slow slave to finish
  if (!SCL_READ(twi_scl))
@@ -435,7 +429,7 @@ uint8_t Twi::status()
  return I2C_OK;
 }
 
-uint8_t Twi::transmit(const uint8_t* data, uint8_t length)
+uint8_t TwiMasterOrSlave::transmit(const uint8_t* data, uint8_t length)
 {
  uint8_t i;
 
@@ -461,20 +455,20 @@ uint8_t Twi::transmit(const uint8_t* data, uint8_t length)
  return 0;
 }
 
-void Twi::attachSlaveRxEvent(void (*function)(uint8_t*, size_t))
+void TwiMasterOrSlave::attachSlaveRxEvent(void (*function)(uint8_t*, size_t, void*))
 {
  twi_onSlaveReceive = function;
 }
 
-void Twi::attachSlaveTxEvent(void (*function)(void))
+void TwiMasterOrSlave::attachSlaveTxEvent(void (*function)(void*))
 {
  twi_onSlaveTransmit = function;
 }
 
 // DO NOT INLINE, inlining reply() in combination with compiler optimizations causes function breakup into
 // parts and the IRAM_ATTR isn't propagated correctly to all parts, which of course causes crashes.
 // TODO: test with gcc 9.x and if it still fails, disable optimization with -fdisable-ipa-fnsplit
-void IRAM_ATTR Twi::reply(uint8_t ack)
+void IRAM_ATTR TwiMasterOrSlave::reply(uint8_t ack)
 {
  // transmit master read ready signal, with or without ack
  if (ack)
@@ -492,7 +486,7 @@ void IRAM_ATTR Twi::reply(uint8_t ack)
 }
 
 
-void IRAM_ATTR Twi::releaseBus(void)
+void IRAM_ATTR TwiMasterOrSlave::releaseBus(void)
 {
  // release bus
  //TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWEA) | _BV(TWINT);
@@ -505,7 +499,7 @@ void IRAM_ATTR Twi::releaseBus(void)
 }
 
 
-void IRAM_ATTR Twi::onTwipEvent(uint8_t status)
+void IRAM_ATTR TwiMasterOrSlave::onTwipEvent(uint8_t status)
 {
  twip_status = status;
  switch (status)
@@ -612,7 +606,7 @@ void IRAM_ATTR Twi::onTwipEvent(uint8_t status)
  }
 }
 
-void IRAM_ATTR Twi::onTimer(void *unused)
+void IRAM_ATTR TwiMasterOrSlave::onTimer(void *unused)
 {
  (void)unused;
  twi.releaseBus();
@@ -621,7 +615,7 @@ void IRAM_ATTR Twi::onTimer(void *unused)
  twi.twip_state = TWIP_BUS_ERR;
 }
 
-void Twi::eventTask(ETSEvent *e)
+void TwiMasterOrSlave::eventTask(ETSEvent *e)
 {
 
  if (e == NULL)
@@ -632,7 +626,7 @@ void Twi::eventTask(ETSEvent *e)
  switch (e->sig)
  {
  case TWI_SIG_TX:
- twi.twi_onSlaveTransmit();
+ twi.twi_onSlaveTransmit(twi.twi_SlaveTargetObject);
 
  // if they didn't change buffer & length, initialize it
  if (twi.twi_txBufferLength == 0)
@@ -649,7 +643,7 @@ void Twi::eventTask(ETSEvent *e)
  case TWI_SIG_RX:
  // ack future responses and leave slave receiver state
  twi.releaseBus();
- twi.twi_onSlaveReceive(twi.twi_rxBuffer, e->par);
+ twi.twi_onSlaveReceive(twi.twi_rxBuffer, e->par, twi.twi_SlaveTargetObject);
  break;
  }
 }
@@ -662,7 +656,7 @@ void Twi::eventTask(ETSEvent *e)
 // Shorthand for if the state is any of the or'd bitmask x
 #define IFSTATE(x) if (twip_state_mask & (x))
 
-void IRAM_ATTR Twi::onSclChange(void)
+void IRAM_ATTR TwiMasterOrSlave::onSclChange(void)
 {
  unsigned int sda;
  unsigned int scl;
@@ -860,7 +854,7 @@ void IRAM_ATTR Twi::onSclChange(void)
  }
 }
 
-void IRAM_ATTR Twi::onSdaChange(void)
+void IRAM_ATTR TwiMasterOrSlave::onSdaChange(void)
 {
  unsigned int sda;
  unsigned int scl;
@@ -998,16 +992,17 @@ extern "C" {
  return twi.transmit(buf, len);
  }
 
- void twi_attachSlaveRxEvent(void (*cb)(uint8_t*, size_t))
+ void twi_attachSlaveRxEventWithTarget(void (*cb)(uint8_t*, size_t, void*))
  {
  twi.attachSlaveRxEvent(cb);
  }
 
- void twi_attachSlaveTxEvent(void (*cb)(void))
+ void twi_attachSlaveTxEventWithTarget(void (*cb)(void*))
  {
  twi.attachSlaveTxEvent(cb);
  }
 
+
  void twi_reply(uint8_t r)
  {
  twi.reply(r);
@@ -1018,9 +1013,9 @@ extern "C" {
  twi.releaseBus();
  }
 
- void twi_enableSlaveMode(void)
+ void twi_enableSlaveModeWithTarget(void* targetObject)
  {
- twi.enableSlave();
+ twi.enableSlave(targetObject);
  }
 
 };