Index: branches/autonomous_recharging/code/projects/libbayboard/i2c.c
===================================================================
--- branches/autonomous_recharging/code/projects/libbayboard/i2c.c	(nonexistent)
+++ branches/autonomous_recharging/code/projects/libbayboard/i2c.c	(revision 968)
@@ -0,0 +1,347 @@
+/**
+ * Copyright (c) 2007 Colony Project
+ * 
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ * 
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ **/
+
+
+/**
+ * @file i2c.c
+ * @brief Implemenation of I2C communications protocol
+ * 
+ * In the case where you have master sends and then a master request to the same
+ * address, you will not give up control of the line because the send and
+ * request addresses are seen as different addresses. In between it will send a
+ * restart but will not give up the line.
+ *
+ * @author CMU Robotics Club, Kevin Woo, Sursh Nidhiry
+ * @bug Not tested.
+ */
+
+#include <avr/interrupt.h>
+#include <util/twi.h>
+
+#include "i2c.h"
+#include "ring_buffer.h"
+
+/**
+ * @defgroup i2c I2C 
+ *
+ * @brief Provides Inter-Interconnected-Communications (I2C)
+ * 
+ * Initiates I2C functions on an ATMega128 which has a fully hardware Two Wire 
+ * Interface (TWI) module. Any Atmel chip with this hardware should be able to
+ * use the software.
+ *
+ * This code will operate in a multi-master enviornment and can be either a
+ * slave or a master at any time (as long as they are not one or the other at
+ * the moment. You can queue up multiple transmission modes in the buffer up to 
+ * the buffer size. The buffer is implemented as a ring buffer.
+ *
+ * It is implemented using callback functions. Whenever you want to send a packet
+ * you can call the built in send function (as a master) and it will send an array
+ * of bytes. Master recieve and slave send/receive are all handled by the call back
+ * functions. It is up to the end user to create functions that will handle the
+ * receiving of packets. Their functions will be called with every byte recieved
+ * so you must either buffer the inputs or handle each one separately.
+ *
+ * On errors we will simply flush the entire buffer.
+ * 
+ * For information on how I2C operates, read the wikipedia article
+ * http://en.wikipedia.org/wiki/I2c
+ * for a good explanation of how it works.
+ * @{
+ */
+
+/** 
+ * @brief Set bit rate 12 = 100kbit/s (max speed setting is 10 for an
+ *  8 MHz clock). It is a divider, so the lower the number the faster the speed.
+ */
+#define I2C_BIT_RATE_DIVIDER 0x0C
+
+static int start_flag;
+
+static fun_mrecv_t master_recv_function;
+static fun_srecv_t slave_recv_function;
+static fun_send_t slave_send_function;
+
+RING_BUFFER_NEW(i2c_buffer, 128, char, i2c_write_buff, i2c_addr_buff);
+
+
+/**
+ * @brief Initializes the i2c module.
+ *
+ * Initializes the I2C module to start listening on the i2c lines. If the callback functions
+ * are not set to null they will be called when that transmission mode is called. The address
+ * is your address that you will listen to when you are not the master.
+ *
+ * @param addr 			Your address on the I2C bus.
+ * @param master_recv 	The address of the function to call when you receive a byte when you are a
+ *                    	master.
+ * @param slave_recv 	The address of the function to call when you are a slave you receive data
+ *								from the master
+ * @param slave_send		The address of the function to call when you are a slave and the master
+ *								requests data from you.
+ *
+ * @return 0 for success, nonzero for failure
+ **/
+int i2c_init(char addr, fun_mrecv_t master_recv, fun_srecv_t slave_recv, fun_send_t slave_send) {
+    master_recv_function = master_recv;
+    slave_recv_function = slave_recv;
+    slave_send_function = slave_send;
+
+    RING_BUFFER_CLEAR(i2c_write_buff);
+    RING_BUFFER_CLEAR(i2c_addr_buff);
+  
+    /* enables twi interrupt, automatic ack sending, and all twi hardware */
+    TWCR =  (_BV(TWEA) | _BV(TWEN) | _BV(TWIE));
+
+    /* sets the bit rate of data transmission */
+    TWBR = I2C_BIT_RATE_DIVIDER;
+
+    /* sets the address (it is stored in the 7 most significant bits) and allows
+     * global messages to be accepted */
+    TWAR = (addr << 1) | 1;
+	
+	sei();
+  
+    return 0;
+}
+
+/**
+ * @brief Sends a byte array over I2C as a master
+ *
+ * Will perform a send over I2C to the destination from data for the ammount of
+ * bytes that bytes is.
+ *
+ * @param dest		Destination address of the data on the I2C bus.
+ * @param data 	The pointer to the byte array of data
+ * @param bytes	The amount of bytes long that the byte array is. This is how
+ *						many bytes from the array that the function will send.
+ *
+ * @return zero for success, nonzero for failure
+ **/
+int i2c_send(char dest, char *data, size_t bytes) {
+    int i;
+
+    /* adding data to be sent to ring buffers is not atomic,
+     * so disable interrupts */
+    cli();
+    for(i = 0; i < bytes; i++) {
+        if(RING_BUFFER_FULL(i2c_write_buff)) {
+            sei();
+            return -1;
+        }
+
+        RING_BUFFER_ADD(i2c_write_buff, data[i]);
+        RING_BUFFER_ADD(i2c_addr_buff, dest << 1);
+    }
+    
+    /* re-enable the interrupts */
+    sei();
+    
+    /* send the start bit, only if this device is not currently master */
+    if(!start_flag) {
+        start_flag = 1;
+        TWCR |= _BV(TWSTA);
+        TWCR |= _BV(TWINT);
+    }
+  
+    return 0;
+}
+ 
+/**
+ * @brief Send a master request to the destination
+ *
+ * Sends a request of data from the target address and calls
+ * the callback function to handle data as it comes in. This function will
+ * not work if the slave has not informationt to send or has nothing implemented
+ * to send it.
+ *
+ * @param dest		The destination that we want to receive information from.
+ *
+ * @return 0 for success, nonzero for failure
+ **/ 
+int i2c_request(char dest) {
+    if(RING_BUFFER_FULL(i2c_write_buff))
+        return -1;
+  
+    RING_BUFFER_ADD(i2c_write_buff, 0);
+    RING_BUFFER_ADD(i2c_addr_buff, (dest << 1) | 1);
+  
+    if(!start_flag) {
+        start_flag = 1;
+        TWCR |= _BV(TWSTA);
+        TWCR |= _BV(TWINT);
+    }
+  
+    return 0;
+}
+
+/** @} **/
+ 
+/**
+ * @brief Interrupt to handle I2C interrupts from the I2C hardware.
+ * 
+ * Uses the status codes from the I2C register to handle the events
+ * needed to advance in I2C stages. For instance, you will get a bit for
+ * receiving a start ack, then a address ack, then a data ack, etc.
+ * The events are handled in each switch case. The status codes are defined
+ * by avr-gcc in /util/twi.h but are the same codes as the Atmel documentation.
+ *
+ * Bytes are sent by popping off the ring buffer. It also will keep track
+ * of what modes the send is in.
+ *
+ * Errors are handled here as well.
+ **/ 
+ISR(TWI_vect) {
+	static char data_to_send;
+	static char addr_to_send = -1;
+	char addr, statusCode;
+  
+	//Get status code (only upper 5 bits)
+	statusCode = (TWSR & 0xF8);
+
+    switch (statusCode) {
+        //Start sent successfully
+        case TW_START:
+        case TW_REP_START:
+            /* Send address and write
+             * ring_buffer will not be empty */
+            RING_BUFFER_REMOVE(i2c_addr_buff, addr_to_send);
+            RING_BUFFER_REMOVE(i2c_write_buff, data_to_send);
+            
+            /* first send the address */
+            TWDR = addr_to_send; 
+            
+            //Turn off start bits
+            TWCR &= ~_BV(TWSTA);
+            break;
+
+        //Master Transmit - Address sent succesfully
+        case TW_MT_SLA_ACK:
+        //Send byte
+            TWDR = data_to_send;
+            //PORTG &= ~_BV(PG2);
+            break;
+	 
+        //Master Transmit - Data sent succesfully
+        case TW_MT_DATA_ACK:    
+            //If there is still data to send
+            if(!RING_BUFFER_EMPTY(i2c_write_buff)) {
+                RING_BUFFER_PEEK(i2c_addr_buff, addr);
+        
+                //Still data for this address
+                if (addr == addr_to_send) {
+                    RING_BUFFER_REMOVE(i2c_addr_buff, addr);
+                    RING_BUFFER_REMOVE(i2c_write_buff, TWDR);
+                    break;
+                //No more data for this address, data for another address -> resend start
+                } else {
+                    TWCR |= _BV(TWSTA);
+                    break;
+                }
+            }
+            /* there are no bytes to send */
+            TWCR |= _BV(TWSTO);
+            start_flag = 0;
+            break; 
+            
+        //Master Transmit - Slave sends a nack, transmit is done
+        case TW_MT_DATA_NACK:
+            //PORTG |= _BV(PG2);
+            TWCR |= _BV(TWSTO);
+            start_flag = 0;
+            break;
+    
+        //Master Receive - Address sent succesfully
+        case TW_MR_SLA_ACK:
+            //PORTG |= _BV(PG2);
+            break;
+            
+        //Master Receive - Data received succesfully
+        case TW_MR_DATA_ACK:
+            if(master_recv_function) {
+                if(!master_recv_function(TWDR)) {
+                    TWCR &= ~_BV(TWEA);
+                }
+            }
+            break;
+            
+        //Master Receive - Slave sends a nack, transmission is done    
+        case TW_MR_DATA_NACK:
+            TWCR |= _BV(TWEA);
+      
+            //If there is still data to send
+            if(!RING_BUFFER_EMPTY(i2c_write_buff)) {
+                TWCR |= _BV(TWSTA);
+                break;
+            }
+      
+            /* there are no bytes to send */
+            TWCR |= _BV(TWSTO);
+            start_flag = 0;  
+            break;
+    
+        //Slave Transmit - Address received
+        case TW_ST_SLA_ACK:
+            break;
+    
+        //Slave Transmit - Nack received, no data requsted
+        case TW_ST_DATA_NACK:
+            break;
+        
+        //Slave Transmit - Data requested, ack received
+        case TW_ST_DATA_ACK:
+            if (slave_send_function) {
+                TWDR = slave_send_function();
+            }
+            break;
+    
+        //Slave Receive - Address received  
+        case TW_SR_SLA_ACK:
+            break;
+    
+        //Slave Receive - Data received, ack returned
+        case TW_SR_DATA_ACK:
+            if(slave_recv_function) {
+                slave_recv_function(TWDR);
+            }
+            
+            break;
+      
+        //Stop sent  
+        case TW_SR_STOP:
+            break;
+	
+        //Problem on the bus, reset everything
+        default:
+            TWCR |= _BV(TWSTO);
+            start_flag = 0;
+            RING_BUFFER_CLEAR(i2c_write_buff);
+            RING_BUFFER_CLEAR(i2c_addr_buff);  	
+    }
+  
+  /* Toggle TWINT so that it resets and executes the commands */
+  TWCR |= _BV(TWINT);
+}
+
Index: branches/autonomous_recharging/code/projects/libbayboard/i2c.h
===================================================================
--- branches/autonomous_recharging/code/projects/libbayboard/i2c.h	(nonexistent)
+++ branches/autonomous_recharging/code/projects/libbayboard/i2c.h	(revision 968)
@@ -0,0 +1,57 @@
+/**
+ * Copyright (c) 2007 Colony Project
+ * 
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ * 
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ **/
+
+
+/** @file i2c.h
+ *  @brief Header file for I2C
+ *
+ *  Contains functions for I2C.
+ *
+ *  @author Kevin Woo and Suresh Nidhiry, Colony Project, CMU Robotics Club
+ **/
+
+
+#ifndef _I2C_H_
+#define _I2C_H_
+
+#include <stddef.h>
+
+/** @brief Address of slave receive handler function **/
+typedef void (*fun_srecv_t)(char);
+
+/** @brief Address of master receive handler function**/
+typedef int (*fun_mrecv_t)(char);
+
+/** @brief Address of slave send handler function**/
+typedef char (*fun_send_t)(void);
+
+int i2c_init(char addr, fun_mrecv_t master_recv, fun_srecv_t slave_recv, fun_send_t slave_send);
+int i2c_send(char dest, char* data, size_t bytes);
+int i2c_request(char dest);
+
+void i2c_packet_rec (char i2c_byte);
+void i2c_packet_sniff(char data);
+#endif
+
