Diff: targets/TARGET_NXP/TARGET_LPC81X/i2c_api.c

Revision:

149:156823d33999

Parent:

144:ef7eb2e8f9f7

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/targets/TARGET_NXP/TARGET_LPC81X/i2c_api.c	Fri Oct 28 11:17:30 2016 +0100
@@ -0,0 +1,513 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2006-2013 ARM Limited
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include "i2c_api.h"
+#include "cmsis.h"
+#include "pinmap.h"
+
+#if DEVICE_I2C
+
+static const SWM_Map SWM_I2C_SDA[] = {
+    {7, 24},
+};
+
+static const SWM_Map SWM_I2C_SCL[] = {
+    {8, 0},
+};
+
+static uint8_t repeated_start = 0;
+
+#define I2C_DAT(x)          (x->i2c->MSTDAT)
+#define I2C_STAT(x)         ((x->i2c->STAT >> 1) & (0x07))
+
+static inline int i2c_status(i2c_t *obj) {
+    return I2C_STAT(obj);
+}
+
+// Wait until the Serial Interrupt (SI) is set
+static int i2c_wait_SI(i2c_t *obj) {
+    int timeout = 0;
+    while (!(obj->i2c->STAT & (1 << 0))) {
+        timeout++;
+        if (timeout > 100000) return -1;
+    }
+    return 0;
+}
+
+static inline void i2c_interface_enable(i2c_t *obj) {
+    obj->i2c->CFG |= (1 << 0);
+}
+
+static inline void i2c_power_enable(i2c_t *obj) {
+    LPC_SYSCON->SYSAHBCLKCTRL |= (1<<5);
+    LPC_SYSCON->PRESETCTRL &= ~(0x1<<6);
+    LPC_SYSCON->PRESETCTRL |= (0x1<<6);
+}
+
+void i2c_init(i2c_t *obj, PinName sda, PinName scl) {
+    obj->i2c = (LPC_I2C_TypeDef *)LPC_I2C;
+    
+    const SWM_Map *swm;
+    uint32_t regVal;
+    
+    swm = &SWM_I2C_SDA[0];
+    regVal = LPC_SWM->PINASSIGN[swm->n] & ~(0xFF << swm->offset);
+    LPC_SWM->PINASSIGN[swm->n] = regVal |  (sda   << swm->offset);
+    
+    swm = &SWM_I2C_SCL[0];
+    regVal = LPC_SWM->PINASSIGN[swm->n] & ~(0xFF << swm->offset);
+    LPC_SWM->PINASSIGN[swm->n] = regVal |  (scl   << swm->offset);
+    
+    // enable power
+    i2c_power_enable(obj);
+    // set default frequency at 100k
+    i2c_frequency(obj, 100000);
+    i2c_interface_enable(obj);
+}
+
+//Actually Wrong. Spec says: First store Address in DAT before setting STA ! 
+//Undefined state when using single byte I2C operations and too much delay
+//between i2c_start and do_i2c_write(Address).
+//Also note that lpc812 will immediately continue reading a byte when Address b0 == 1
+inline int i2c_start(i2c_t *obj) {
+    int status = 0;
+    if (repeated_start) {
+        obj->i2c->MSTCTL = (1 << 1) | (1 << 0);
+        repeated_start = 0;
+    } else {
+        obj->i2c->MSTCTL = (1 << 1);
+    }
+    return status;
+}
+
+//Generate Stop condition and wait until bus is Idle
+//Will also send NAK for previous RD
+inline int i2c_stop(i2c_t *obj) {
+    int timeout = 0;
+
+    obj->i2c->MSTCTL = (1 << 2) | (1 << 0); // STP bit and Continue bit. Sends NAK to complete previous RD
+    
+    //Spin until Ready (b0 == 1)and Status is Idle (b3..b1 == 000)
+    while ((obj->i2c->STAT & ((7 << 1) | (1 << 0))) != ((0 << 1) | (1 << 0))) { 
+        timeout ++;
+        if (timeout > 100000) return 1;
+    }
+
+    return 0;
+}
+
+static inline int i2c_do_write(i2c_t *obj, int value, uint8_t addr) {
+    // write the data
+    I2C_DAT(obj) = value;
+    
+    if (!addr)
+        obj->i2c->MSTCTL = (1 << 0);
+    
+    // wait and return status
+    i2c_wait_SI(obj);
+    return i2c_status(obj);
+}
+
+static inline int i2c_do_read(i2c_t *obj, int last) {
+    // wait for it to arrive
+    i2c_wait_SI(obj);
+    if (!last)
+        obj->i2c->MSTCTL = (1 << 0);
+    
+    // return the data
+    return (I2C_DAT(obj) & 0xFF);
+}
+
+void i2c_frequency(i2c_t *obj, int hz) {
+    // No peripheral clock divider on the M0
+    uint32_t PCLK = SystemCoreClock;
+    
+    uint32_t clkdiv = PCLK / (hz * 4) - 1;
+    
+    obj->i2c->DIV = clkdiv;
+    obj->i2c->MSTTIME = 0;
+}
+
+// The I2C does a read or a write as a whole operation
+// There are two types of error conditions it can encounter
+//  1) it can not obtain the bus
+//  2) it gets error responses at part of the transmission
+//
+// We tackle them as follows:
+//  1) we retry until we get the bus. we could have a "timeout" if we can not get it
+//      which basically turns it in to a 2)
+//  2) on error, we use the standard error mechanisms to report/debug
+//
+// Therefore an I2C transaction should always complete. If it doesn't it is usually
+// because something is setup wrong (e.g. wiring), and we don't need to programatically
+// check for that
+
+//New version WH, Tested OK for Start and Repeated Start
+//Old version was Wrong: Calls i2c_start without setting address, i2c_do_read continues before checking status, status check for wrong value
+int i2c_read(i2c_t *obj, int address, char *data, int length, int stop) {
+    int count, status;
+    
+    //Store the address+RD and then generate STA
+    I2C_DAT(obj) = address | 0x01;
+    i2c_start(obj);    
+
+    // Wait for completion of STA and Sending of SlaveAddress+RD and first Read byte
+    i2c_wait_SI(obj);
+    status = i2c_status(obj);    
+    if (status == 0x03) { // NAK on SlaveAddress
+        i2c_stop(obj);
+        return I2C_ERROR_NO_SLAVE;
+    }
+
+    // Read in all except last byte
+    for (count = 0; count < (length-1); count++) {
+        
+      // Wait for it to arrive, note that first byte read after address+RD is already waiting
+      i2c_wait_SI(obj);
+      status = i2c_status(obj);
+      if (status != 0x01) { // RX RDY
+        i2c_stop(obj);
+        return count;
+      }
+      data[count] = I2C_DAT(obj) & 0xFF; // Store read byte
+
+      obj->i2c->MSTCTL = (1 << 0); // Send ACK and Continue to read
+    }
+    
+    // Read final byte
+    // Wait for it to arrive
+    i2c_wait_SI(obj);
+
+    status = i2c_status(obj);
+    if (status != 0x01) { // RX RDY
+      i2c_stop(obj);
+      return count;
+    }
+    data[count] = I2C_DAT(obj) & 0xFF; // Store final read byte
+
+    // If not repeated start, send stop.
+    if (stop) {
+        i2c_stop(obj); // Also sends NAK for last read byte
+    } else {
+        repeated_start = 1;
+    }
+   
+    return length;
+}
+
+
+
+//New version WH, Tested OK for Start and Repeated Start
+//Old version was Wrong: Calls i2c_start without setting address first
+int i2c_write(i2c_t *obj, int address, const char *data, int length, int stop) {
+    int i, status;
+
+    //Store the address+/WR and then generate STA
+    I2C_DAT(obj) = address & 0xFE;   
+    i2c_start(obj);
+    
+    // Wait for completion of STA and Sending of SlaveAddress+/WR
+    i2c_wait_SI(obj);
+    status = i2c_status(obj);    
+    if (status == 0x03) { // NAK SlaveAddress
+        i2c_stop(obj);
+        return I2C_ERROR_NO_SLAVE;
+    }
+    
+    //Write all bytes
+    for (i=0; i<length; i++) {
+        status = i2c_do_write(obj, data[i], 0);
+        if (status != 0x02) { // TX RDY. Handles a Slave NAK on datawrite
+            i2c_stop(obj);
+            return i;
+        }
+    }
+    
+    // If not repeated start, send stop.
+    if (stop) {
+        i2c_stop(obj);
+    } else {
+        repeated_start = 1;
+    }
+    
+    return length;
+}
+
+
+
+void i2c_reset(i2c_t *obj) {
+    i2c_stop(obj);
+}
+
+int i2c_byte_read(i2c_t *obj, int last) {
+    return (i2c_do_read(obj, last) & 0xFF);
+}
+
+int i2c_byte_write(i2c_t *obj, int data) {
+    int ack;
+    int status = i2c_do_write(obj, (data & 0xFF), 0);
+    
+    switch(status) {
+        case 2:
+            ack = 1;
+            break;
+        default:
+            ack = 0;
+            break;
+    }
+
+    return ack;
+}
+
+#if DEVICE_I2CSLAVE
+
+#define I2C_SLVDAT(x)        (x->i2c->SLVDAT)
+#define I2C_SLVSTAT(x)      ((x->i2c->STAT >> 9) & (0x03))
+#define I2C_SLVSI(x)        ((x->i2c->STAT >> 8) & (0x01))
+//#define I2C_SLVCNT(x)        (x->i2c->SLVCTL = (1 << 0))
+//#define I2C_SLVNAK(x)        (x->i2c->SLVCTL = (1 << 1))
+
+#if(0)
+// Wait until the Slave Serial Interrupt (SI) is set
+// Timeout when it takes too long.
+static int i2c_wait_slave_SI(i2c_t *obj) {
+    int timeout = 0;
+    while (!(obj->i2c->STAT & (1 << 8))) {
+        timeout++;
+        if (timeout > 100000) return -1;
+    }
+    return 0;
+}
+#endif
+
+void i2c_slave_mode(i2c_t *obj, int enable_slave) {
+
+  if (enable_slave) {
+//    obj->i2c->CFG &= ~(1 << 0); //Disable Master mode    
+    obj->i2c->CFG |=  (1 << 1); //Enable Slave mode
+  }
+  else {
+//    obj->i2c->CFG |=  (1 << 0); //Enable Master mode    
+    obj->i2c->CFG &= ~(1 << 1); //Disable Slave mode
+  } 
+}
+
+// Wait for next I2C event and find out what is going on
+//
+int i2c_slave_receive(i2c_t *obj) {
+  int addr;
+  
+  // Check if there is any data pending
+  if (! I2C_SLVSI(obj)) {
+    return 0; //NoData    
+  };
+  
+  // Check State
+  switch(I2C_SLVSTAT(obj)) {
+    case 0x0: // Slave address plus R/W received 
+              // At least one of the four slave addresses has been matched by hardware.
+              // You can figure out which address by checking Slave address match Index in STAT register.
+               
+              // Get the received address
+              addr = I2C_SLVDAT(obj) & 0xFF;
+              // Send ACK on address and Continue
+              obj->i2c->SLVCTL = (1 << 0); 
+              
+              if (addr == 0x00) {
+                return 2; //WriteGeneral
+              }  
+              //check the RW bit
+              if ((addr & 0x01) == 0x01) {
+                return 1; //ReadAddressed
+              }
+              else {
+                return 3; //WriteAddressed
+              }
+              //break;
+    
+    case 0x1: // Slave receive. Received data is available (Slave Receiver mode).
+              // Oops, should never get here...     
+              obj->i2c->SLVCTL = (1 << 1);  // Send NACK on received data, try to recover...
+              return 0; //NoData        
+              
+    case 0x2: // Slave transmit. Data can be transmitted (Slave Transmitter mode).
+              // Oops, should never get here...         
+              I2C_SLVDAT(obj) = 0xFF;       // Send dummy data for transmission
+              obj->i2c->SLVCTL = (1 << 0);  // Continue and try to recover...
+              return 0; //NoData        
+    
+    case 0x3: // Reserved.
+    default:  // Oops, should never get here... 
+              obj->i2c->SLVCTL = (1 << 0);  // Continue and try to recover...              
+              return 0; //NoData        
+              //break; 
+  } //switch status  
+}
+
+// The dedicated I2C Slave byte read and byte write functions need to be called
+// from 'common' mbed I2CSlave API for devices that have separate Master and 
+// Slave engines such as the lpc812 and lpc1549.
+
+//Called when Slave is addressed for Write, Slave will receive Data in polling mode
+//Parameter last=1 means received byte will be NACKed.
+int i2c_slave_byte_read(i2c_t *obj, int last) {
+  int data;
+  
+  // Wait for data
+  while (!I2C_SLVSI(obj)); // Wait forever
+//if (i2c_wait_slave_SI(obj) != 0) {return -2;} // Wait with timeout
+
+  // Dont bother to check State, were not returning it anyhow..
+//if (I2C_SLVSTAT(obj)) == 0x01) {
+  // Slave receive. Received data is available (Slave Receiver mode).    
+//};
+
+  data = I2C_SLVDAT(obj) & 0xFF; // Get and store the received data
+  if (last) {
+    obj->i2c->SLVCTL = (1 << 1);  // Send NACK on received data and Continue 
+  }    
+  else {  
+    obj->i2c->SLVCTL = (1 << 0);  // Send ACK on data and Continue to read                
+  }
+ 
+  return data; 
+}
+
+
+//Called when Slave is addressed for Read, Slave will send Data in polling mode
+//
+int i2c_slave_byte_write(i2c_t *obj, int data) {
+
+  // Wait until Ready 
+  while (!I2C_SLVSI(obj)); // Wait forever
+//  if (i2c_wait_slave_SI(obj) != 0) {return -2;} // Wait with timeout
+
+  // Check State
+  switch(I2C_SLVSTAT(obj)) {
+    case 0x0: // Slave address plus R/W received 
+              // At least one of the four slave addresses has been matched by hardware.
+              // You can figure out which address by checking Slave address match Index in STAT register.                
+              // I2C Restart occurred
+              return -1; 
+              //break;    
+    case 0x1: // Slave receive. Received data is available (Slave Receiver mode).
+              // Should not get here... 
+              return -2;
+              //break;                
+    case 0x2: // Slave transmit. Data can be transmitted (Slave Transmitter mode).
+              I2C_SLVDAT(obj) = data & 0xFF; // Store the data for transmission
+              obj->i2c->SLVCTL = (1 << 0);   // Continue to send
+              
+              return 1;    
+              //break;      
+    case 0x3: // Reserved.
+    default:
+              // Should not get here... 
+              return -3;
+              //break; 
+  } // switch status
+}
+
+
+//Called when Slave is addressed for Write, Slave will receive Data in polling mode
+//Parameter length (>=1) is the maximum allowable number of bytes. All bytes will be ACKed.
+int i2c_slave_read(i2c_t *obj, char *data, int length) {
+  int count=0;
+  
+  // Read and ACK all expected bytes
+  while (count < length) {
+    // Wait for data
+    while (!I2C_SLVSI(obj)); // Wait forever
+//    if (i2c_wait_slave_SI(obj) != 0) {return -2;} // Wait with timeout
+
+    // Check State
+    switch(I2C_SLVSTAT(obj)) {
+      case 0x0: // Slave address plus R/W received 
+                // At least one of the four slave addresses has been matched by hardware.
+                // You can figure out which address by checking Slave address match Index in STAT register.                
+                // I2C Restart occurred
+                return -1; 
+                //break;
+    
+      case 0x1: // Slave receive. Received data is available (Slave Receiver mode).
+                data[count] = I2C_SLVDAT(obj) & 0xFF; // Get and store the received data
+                obj->i2c->SLVCTL = (1 << 0);          // Send ACK on data and Continue to read                
+                break;
+
+      case 0x2: // Slave transmit. Data can be transmitted (Slave Transmitter mode).
+      case 0x3: // Reserved.
+      default:  // Should never get here... 
+                return -2;
+                //break; 
+    } // switch status
+    
+    count++;
+  } // for all bytes
+    
+  return count; // Received the expected number of bytes
+}
+
+
+//Called when Slave is addressed for Read, Slave will send Data in polling mode
+//Parameter length (>=1) is the maximum number of bytes. Exit when Slave byte is NACKed.
+int i2c_slave_write(i2c_t *obj, const char *data, int length) {
+  int count;
+  
+  // Send and all bytes or Exit on NAK
+  for (count=0; count < length; count++) {
+    // Wait until Ready for data 
+    while (!I2C_SLVSI(obj)); // Wait forever
+//    if (i2c_wait_slave_SI(obj) != 0) {return -2;} // Wait with timeout
+
+    // Check State
+    switch(I2C_SLVSTAT(obj)) {
+      case 0x0: // Slave address plus R/W received 
+                // At least one of the four slave addresses has been matched by hardware.
+                // You can figure out which address by checking Slave address match Index in STAT register.                
+                // I2C Restart occurred
+                return -1; 
+                //break;    
+      case 0x1: // Slave receive. Received data is available (Slave Receiver mode).
+                // Should not get here... 
+                return -2;
+                //break;                
+      case 0x2: // Slave transmit. Data can be transmitted (Slave Transmitter mode).
+                I2C_SLVDAT(obj) = data[count] & 0xFF; // Store the data for transmission
+                obj->i2c->SLVCTL = (1 << 0);          // Continue to send
+                break;      
+      case 0x3: // Reserved.
+      default:
+              // Should not get here... 
+              return -3;
+              //break; 
+    } // switch status
+  } // for all bytes
+     
+  return length; // Transmitted the max number of bytes
+}
+
+
+// Set the four slave addresses. 
+void i2c_slave_address(i2c_t *obj, int idx, uint32_t address, uint32_t mask) {
+  obj->i2c->SLVADR0   = (address & 0xFE); // Store address in address 0 register
+  obj->i2c->SLVADR1   = (0x00    & 0xFE); // Store general call write address in address 1 register
+  obj->i2c->SLVADR2   = (0x01);           // Disable address 2 register
+  obj->i2c->SLVADR3   = (0x01);           // Disable address 3 register
+  obj->i2c->SLVQUAL0  = (mask & 0xFE);    // Qualifier mask for address 0 register. Any maskbit that is 1 will always be a match 
+}
+
+#endif
+
+#endif