--- /dev/null
+/*
+ * Copyright (c) 2009 Communication Group and Eislab at
+ * Lulea University of Technology
+ *
+ * Contact: Laurynas Riliskis, LTU
+ * Mail: laurynas.riliskis@ltu.se
+ * All rights reserved.
+ *
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * - Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * - Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the
+ * distribution.
+ * - Neither the name of Communication Group at Lulea University of Technology
+ * nor the names of its contributors may be used to endorse or promote
+ * products derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL STANFORD
+ * UNIVERSITY OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "I2C.h"
+
+/**
+ * This module implements a software I2CPacket with 7-bit addressing.
+ * The SDA and SCL pins must have pull-up resistors.
+ *
+ * This code was written with help from the I2C Wikipedia page:
+ * http://en.wikipedia.org/wiki/I%C2%B2C
+ *
+ * @param speed The number of micro seconds
+ * @author Henrik Makitaavola <henrik.makitaavola@gmail.com>
+ */
+generic module SoftwareI2CPacketC(int speed)
+{
+ provides interface I2CPacket<TI2CBasicAddr>;
+
+ uses interface GeneralIO as SDA;
+ uses interface GeneralIO as SCL;
+ uses interface BusyWait<TMicro, uint16_t>;
+}
+implementation
+{
+ enum
+ {
+ S_IDLE,
+ S_BUSY,
+ };
+
+ uint8_t m_state = S_IDLE;
+ uint16_t m_addr;
+ uint8_t m_length;
+ uint8_t* m_data;
+ error_t m_error;
+ bool m_read;
+
+ uint8_t READSDA()
+ {
+ call SDA.makeInput();
+ return call SDA.get();
+ }
+
+ uint8_t READSCL()
+ {
+ call SCL.makeInput();
+ return call SCL.get();
+ }
+
+ void CLRSCL()
+ {
+ call SCL.clr();
+ call SCL.makeOutput();
+ }
+
+ void CLRSDA()
+ {
+ call SDA.clr();
+ call SDA.makeOutput();
+ }
+
+ void i2cDelay(uint16_t u) {
+ call BusyWait.wait(u);
+ }
+
+ uint8_t i2cReadBit(void)
+ {
+ uint8_t bit;
+
+ /* lets the slave drive data */
+ READSDA();
+ i2cDelay(speed/2);
+ /* Clock stretching */
+ while (READSCL() == 0);
+ /* SCL is high, now data is valid */
+ bit = READSDA();
+ i2cDelay(speed/2);
+ CLRSCL();
+ return bit;
+ }
+
+ error_t i2cWriteBit(bool bit)
+ {
+ if (bit)
+ READSDA();
+ else
+ CLRSDA();
+ i2cDelay(speed/2);
+ /* Clock stretching */
+ while (READSCL() == 0);
+ /* SCL is high, now data is valid */
+ /* check that nobody is driving SDA */
+ if (bit && READSDA() == 0)
+ return FAIL;
+ i2cDelay(speed/2);
+ CLRSCL();
+ return SUCCESS;
+ }
+
+ error_t i2cStartCond(void)
+ {
+ if (READSDA() == 0)
+ return FAIL;
+ /* SCL is high, set SDA from 1 to 0 */
+ CLRSDA();
+ i2cDelay(speed/2);
+ CLRSCL();
+ return SUCCESS;
+ }
+
+ error_t i2cStopCond(void)
+ {
+ /* set SDA to 0 */
+ CLRSDA();
+ i2cDelay(speed/2);
+ /* Clock stretching */
+ while (READSCL() == 0);
+ /* SCL is high, set SDA from 0 to 1 */
+ if (READSDA() == 0)
+ return FAIL;
+ i2cDelay(speed/2);
+ return SUCCESS;
+ }
+
+ error_t i2cTx(uint8_t byte)
+ {
+ uint8_t bit;
+ uint8_t ack;
+ error_t error = SUCCESS;
+
+ for (bit = 0; bit < 8; bit++) {
+ error = ecombine(error, i2cWriteBit(byte & 0x80));
+ byte <<= 1;
+ }
+
+ // The ack bit is 0 for success
+ if (!i2cReadBit())
+ {
+ return ecombine(error, SUCCESS);
+ }
+ else
+ {
+ return FAIL;
+ }
+ }
+
+ uint8_t i2cRx (bool nack)
+ {
+ uint8_t byte = 0;
+ uint8_t bit;
+
+ for (bit = 0; bit < 8; bit++) {
+ byte <<= 1;
+ byte |= i2cReadBit();
+ }
+ i2cWriteBit(nack);
+ return byte;
+ }
+
+ task void signalTask()
+ {
+ uint16_t addr;
+ uint8_t length;
+ uint8_t* data;
+ error_t error;
+ bool read;
+ atomic
+ {
+ addr = m_addr;
+ length = m_length;
+ data = m_data;
+ error = m_error;
+ m_state = S_IDLE;
+ read = m_read;
+ }
+ if (read)
+ {
+ signal I2CPacket.readDone(error, addr, length, data);
+ }
+ else
+ {
+ signal I2CPacket.writeDone(error, addr, length, data);
+ }
+ }
+
+ async command error_t I2CPacket.read(i2c_flags_t flags, uint16_t addr, uint8_t length, uint8_t* data)
+ {
+ uint8_t i;
+ error_t error = SUCCESS;
+
+ // Both I2C_STOP and I2C_ACK_END flags are not allowed at the same time.
+ if ((flags & I2C_STOP) && (flags & I2C_ACK_END))
+ {
+ return EINVAL;
+ }
+
+ atomic
+ {
+ if (m_state == S_IDLE)
+ {
+ m_state = S_BUSY;
+ }
+ else
+ {
+ return EBUSY;
+ }
+ }
+ atomic
+ {
+ if (flags & I2C_START)
+ {
+ error = ecombine(error, i2cStartCond());
+ error = ecombine(error, i2cTx(addr+1));
+ }
+
+ // Only read data from the device if length is >0.
+ // TODO(henrik): Should a data length of 0 be a invalid input?
+ if (length > 0)
+ {
+ // Read the data from the device.
+ for (i = 0; i < length-1; ++i)
+ {
+ data[i] = i2cRx(false);
+ }
+ if (flags & I2C_ACK_END)
+ {
+ data[length-1] = i2cRx(false);
+ }
+ else
+ {
+ data[length-1] = i2cRx(true);
+ }
+ }
+ if (flags & I2C_STOP)
+ {
+ error = ecombine(error, i2cStopCond());
+ }
+
+ m_error = error;
+ m_addr = addr;
+ m_length = length;
+ m_data = data;
+ m_read = true;
+ }
+ post signalTask();
+
+ return SUCCESS;
+ }
+
+ async command error_t I2CPacket.write(i2c_flags_t flags, uint16_t addr, uint8_t length, uint8_t* data)
+ {
+ uint8_t i;
+ error_t error = SUCCESS;
+
+ atomic
+ {
+ if (m_state == S_IDLE)
+ {
+ m_state = S_BUSY;
+ }
+ else
+ {
+ return EBUSY;
+ }
+ }
+ atomic
+ {
+ if (flags & I2C_START)
+ {
+ error = ecombine(error, i2cStartCond());
+ }
+
+ i2cTx(addr);
+
+ // Send the data to the device.
+ for (i = 0; i < length; ++i)
+ {
+ error = ecombine(error, i2cTx(data[i]));
+ }
+
+ if (flags & I2C_STOP)
+ {
+ error = ecombine(error, i2cStopCond());
+ }
+
+ m_error = error;
+ m_addr = addr;
+ m_length = length;
+ m_data = data;
+ m_read = false;
+ }
+ post signalTask();
+ return SUCCESS;
+ }
+}
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projects / tinyos-2.x.git / blobdiff