Diff: I2CTransaction.cpp

Revision:

0:96a7926b9d64

Child:

1:5d9e9c0682f0

Child:

2:19e7e472a51f

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/I2CTransaction.cpp	Wed May 21 21:12:32 2014 +0000
@@ -0,0 +1,174 @@
+#include "I2CTransaction.h"
+
+/**
+    I2C Transaction Class.
+    
+    Author: Andrew H. Fagg  (May, 2014)
+    
+    TODO: finish this description
+    
+    This class provides:
+    - Interrupt-driven I2C master functionality
+    - Representations of whole transactions
+    
+    I2C Transactions generally come in two varieties: a write and a write followed by a read
+
+
+
+Notes:
+    I2C Status codes:
+    - 32: write NO-ACK
+    - 72: read NO-ACK
+    - 40: write ACK
+    - 88: read ACK
+*/
+
+// Initialization of static member (kind of gross to do it this way)
+//MODI2C* I2CTransaction::i2c = new MODI2C(p9, p10);
+MODI2C* I2CTransaction::i2c = new MODI2C(p28, p27);
+
+/**
+    Transaction constructor
+    
+    @param I2C address (7-bit address)
+    @param writePacket Pointer to the data structure to be written
+    @param writePacketLength Number of bytes to be written
+    @param readPacket Pointer to the data structure to be filled during the read (NULL = none)
+    @param readPacketLength Number of bytes to read
+*/
+
+I2CTransaction::I2CTransaction(int address, char* writePacket, int writePacketLength, char* readPacket, int readPacketLength)
+{
+    this->address = address;
+    this->writePacket = writePacket;
+    this->writePacketLength = writePacketLength;
+    this->readPacket = readPacket;
+    this->readPacketLength = readPacketLength;
+    if(readPacket == NULL) this->readPacketLength = 0;
+    status[0] = status[1] = -1;
+}
+
+/**
+    Set the I2C bus frequency
+    
+    @param frequency in Hertz
+*/
+
+void I2CTransaction::setFrequency(int frequency)
+{
+    i2c->frequency(frequency);
+}
+
+/**
+    Indicate whether the transaction has completed (whether successful or not)
+    
+    Note: assumes that for the case with no read part of the transaction, status[1]
+    has been left in its initial state (-1)
+*/
+
+bool I2CTransaction::completed()
+{
+    return(status[0] != 0 && status[1] != 0);
+}
+
+/**
+    Return the specified status code for this transaction
+    
+    @param i 0 = write status code; 1 = read status code
+    @return Status code (see documentation at top of this file)
+*/
+
+int I2CTransaction::getStatus(int i)
+{
+    if(i >= 0 && i <= 1) return status[i];
+    else return -1;
+}
+
+/**
+    Start a transaction.
+    
+    Does not initiate a transaction if it is already in progress.
+    
+    Note: no error checking yet on the read and write calls
+    
+    @return true if transaction has been initiated; false if it is already in progress
+*/
+
+bool I2CTransaction::initiateTransaction()
+{
+    if(!completed()) {
+        // Already in progress: bail
+        return false;
+    } else {
+        // Start the write
+        i2c->write(address << 1, writePacket, writePacketLength, false, &(status[0]));
+        
+        // Start the read if it exists
+        if(readPacket != NULL) {
+            i2c->read_nb(address << 1, readPacket, readPacketLength, false, &(status[1]));
+        }
+        return true;
+    }
+}
+
+/**
+    Wait until the transaction has completed, up to the specified number of milliseconds
+    
+    @param timeout Number of milliseconds to wait
+    
+    @return true if transaction completed; false if timed out
+*/
+
+bool I2CTransaction::waitForCompletion(int timeout)
+{
+    for(int i = 0; i < timeout; ++i) {
+        if(this->completed()) return true;
+        wait_ms(1);
+    }
+    return(false);
+}
+
+/**
+    Display the transaction status codes
+
+    @param pc Pointer to an initialized serial handler
+    @param strg String description of this transaction
+*/
+
+void I2CTransaction::displayStatus(Serial *pc, char* strg)
+{
+    if(readPacket == NULL) {
+        // Write only
+        pc->printf("%s\t%d\n\r", strg, status[0]);
+    } else {
+        // Write - Read
+        pc->printf("%s\t%d\t%d\n\r", strg, status[0], status[1]);
+    }
+}
+
+/**
+    Check that the transaction was successfully completed.
+
+    @return true if successful, false if not
+*/
+
+bool I2CTransaction::success()
+{
+    // Write transaction must have completed with the correct status code (40)
+    // Read transaction, if it exists, must also complete correctly (88)
+    return (status[0] == 40) && (readPacket == NULL || status[1] == 88);
+}
+
+
+/**
+    Check that the transaction has an error
+
+    @return true if error, false if not
+*/
+
+bool I2CTransaction::error()
+{
+    // Write transaction has completed with an error code (can't be 0 (in progress) or 40 (correct))
+    // Read transaction, if it exists, has completed with an error code (can't be 0 (in progress) or 88 (correct))
+    return (status[0] != 0 && status[0] != 40) || (readPacket != NULL && status[1] != 0 && status[1] != 88);
+}
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