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i2cmaster.c
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1/*
2 * Copyright (c) 2010, Swedish Institute of Computer Science.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. Neither the name of the Institute nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * This file is part of the Contiki operating system.
30 *
31 */
32
33/**
34 * \file
35 * I2C communication device drivers for Zolertia Z1 sensor node.
36 * \author
37 * Enric M. Calvo, Zolertia <ecalvo@zolertia.com>
38 * Marcus Lundén, SICS <mlunden@sics.se>
39 */
40
41#include "i2cmaster.h"
42#include "isr_compat.h"
43
44signed char tx_byte_ctr, rx_byte_ctr;
45unsigned char rx_buf[2];
46unsigned char *tx_buf_ptr;
47unsigned char *rx_buf_ptr;
48unsigned char receive_data;
49unsigned char transmit_data1;
50unsigned char transmit_data2;
51unsigned char prescale_lsb = I2C_PRESC_Z1_LSB;
52unsigned char prescale_msb = I2C_PRESC_Z1_MSB;
53volatile unsigned int i; /* volatile to prevent optimization */
54
55/* ------------------------------------------------------------------------------
56 * Change the data rate prior initializing transmission or reception
57 * ----------------------------------------------------------------------------- */
58void
59i2c_setrate(uint8_t p_lsb, uint8_t p_msb)
60{
61 prescale_lsb = p_lsb;
62 prescale_lsb = p_msb;
63}
64/* ------------------------------------------------------------------------------
65 * This function initializes the USCI module for master-receive operation.
66 * ----------------------------------------------------------------------------- */
67void
68i2c_receiveinit(uint8_t slave_address)
69{
70 UCB1CTL1 = UCSWRST; /* Enable SW reset */
71 UCB1CTL0 = UCMST + UCMODE_3 + UCSYNC; /* I2C Master, synchronous mode */
72 UCB1CTL1 = UCSSEL_2 | UCSWRST; /* Use SMCLK, keep SW reset */
73 UCB1BR0 = prescale_lsb; /* prescaler (default 400 kHz) */
74 UCB1BR1 = prescale_msb;
75 UCB1I2CSA = slave_address; /* set slave address */
76 UCB1CTL1 &= ~UCTR; /* I2C Receiver */
77 UCB1CTL1 &= ~UCSWRST; /* Clear SW reset, resume operation */
78 UCB1I2CIE = UCNACKIE;
79#if I2C_RX_WITH_INTERRUPT
80 UC1IE = UCB1RXIE; /* Enable RX interrupt if desired */
81#endif
82}
83/* ------------------------------------------------------------------------------
84 * Initializes USCI for master-transmit operation.
85 * ------------------------------------------------------------------------------ */
86void
87i2c_transmitinit(uint8_t slave_address)
88{
89 UCB1CTL1 |= UCSWRST; /* Enable SW reset */
90 UCB1CTL0 |= (UCMST | UCMODE_3 | UCSYNC); /* I2C Master, synchronous mode */
91 UCB1CTL1 = UCSSEL_2 + UCSWRST; /* Use SMCLK, keep SW reset */
92 UCB1BR0 = prescale_lsb; /* prescaler (default 400 kHz) */
93 UCB1BR1 = prescale_msb;
94 UCB1I2CSA = slave_address; /* Set slave address */
95 UCB1CTL1 &= ~UCSWRST; /* Clear SW reset, resume operation */
96 UCB1I2CIE = UCNACKIE;
97 UC1IE = UCB1TXIE; /* Enable TX ready interrupt */
98}
99/* ------------------------------------------------------------------------------
100 * This function is used to start an I2C communication in master-receiver mode WITHOUT INTERRUPTS
101 * for more than 1 byte
102 * ------------------------------------------------------------------------------ */
103static volatile uint8_t rx_byte_tot = 0;
104uint8_t
105i2c_receive_n(uint8_t byte_ctr, uint8_t *rx_buf)
106{
107
108 rx_byte_tot = byte_ctr;
109 rx_byte_ctr = byte_ctr;
110 rx_buf_ptr = rx_buf;
111
112 while((UCB1CTL1 & UCTXSTT) || (UCB1STAT & UCNACKIFG)) /* Slave acks address or not? */
113 PRINTFDEBUG("____ UCTXSTT not clear OR NACK received\n");
114
115#if I2C_RX_WITH_INTERRUPT
116 PRINTFDEBUG(" RX Interrupts: YES \n");
117
118 /* SPECIAL-CASE: Stop condition must be sent while receiving the 1st byte for 1-byte only read operations */
119 if(rx_byte_tot == 1) { /* See page 537 of slau144e.pdf */
120 dint();
121 UCB1CTL1 |= UCTXSTT; /* I2C start condition */
122 while(UCB1CTL1 & UCTXSTT) /* Waiting for Start bit to clear */
123 PRINTFDEBUG("____ STT clear wait\n");
124 UCB1CTL1 |= UCTXSTP; /* I2C stop condition */
125 eint();
126 } else { /* all other cases */
127 UCB1CTL1 |= UCTXSTT; /* I2C start condition */
128 }
129 return 0;
130
131#else
132 uint8_t n_received = 0;
133
134 PRINTFDEBUG(" RX Interrupts: NO \n");
135
136 UCB1CTL1 |= UCTXSTT; /* I2C start condition */
137
138 while(rx_byte_ctr > 0) {
139 if(UC1IFG & UCB1RXIFG) { /* Waiting for Data */
140 rx_buf[rx_byte_tot - rx_byte_ctr] = UCB1RXBUF;
141 rx_byte_ctr--;
142 UC1IFG &= ~UCB1RXIFG; /* Clear USCI_B1 RX int flag */
143 n_received++;
144 }
145 }
146 UCB1CTL1 |= UCTXSTP; /* I2C stop condition */
147 return n_received;
148#endif
149}
150/* ------------------------------------------------------------------------------
151 * This function is used to check if there is communication in progress.
152 * ------------------------------------------------------------------------------ */
153uint8_t
154i2c_busy(void)
155{
156 return UCB1STAT & UCBBUSY;
157}
158/*----------------------------------------------------------------------------
159 * Setup ports and pins for I2C use.
160 * ------------------------------------------------------------------------------ */
161
162void
163i2c_enable(void)
164{
165 I2C_PxSEL |= (I2C_SDA | I2C_SCL); /* Secondary function (USCI) selected */
166 I2C_PxSEL2 |= (I2C_SDA | I2C_SCL); /* Secondary function (USCI) selected */
167 I2C_PxDIR |= I2C_SCL; /* SCL is output (not needed?) */
168 I2C_PxDIR &= ~I2C_SDA; /* SDA is input (not needed?) */
169 I2C_PxREN |= (I2C_SDA | I2C_SCL); /* Activate internal pull-up/-down resistors */
170 I2C_PxOUT |= (I2C_SDA | I2C_SCL); /* Select pull-up resistors */
171}
172void
173i2c_disable(void)
174{
175 I2C_PxSEL &= ~(I2C_SDA | I2C_SCL); /* GPIO function selected */
176 I2C_PxSEL2 &= ~(I2C_SDA | I2C_SCL); /* GPIO function selected */
177 I2C_PxREN &= ~(I2C_SDA | I2C_SCL); /* Deactivate internal pull-up/-down resistors */
178 I2C_PxOUT &= ~(I2C_SDA | I2C_SCL); /* Select pull-up resistors */
179}
180/* ------------------------------------------------------------------------------
181 * This function is used to start an I2C communication in master-transmit mode.
182 * ------------------------------------------------------------------------------ */
183static volatile uint8_t tx_byte_tot = 0;
184void
185i2c_transmit_n(uint8_t byte_ctr, uint8_t *tx_buf)
186{
187 tx_byte_tot = byte_ctr;
188 tx_byte_ctr = byte_ctr;
189 tx_buf_ptr = tx_buf;
190 UCB1CTL1 |= UCTR + UCTXSTT; /* I2C TX, start condition */
191}
192/*----------------------------------------------------------------------------*/
193ISR(USCIAB1TX, i2c_tx_interrupt)
194{
195 /* TX Part */
196 if(UC1IFG & UCB1TXIFG) { /* TX int. condition */
197 if(tx_byte_ctr == 0) {
198 UCB1CTL1 |= UCTXSTP; /* I2C stop condition */
199 UC1IFG &= ~UCB1TXIFG; /* Clear USCI_B1 TX int flag */
200 } else {
201 UCB1TXBUF = tx_buf_ptr[tx_byte_tot - tx_byte_ctr];
202 tx_byte_ctr--;
203 }
204 }
205 /* RX Part */
206#if I2C_RX_WITH_INTERRUPT
207 else if(UC1IFG & UCB1RXIFG) { /* RX int. condition */
208 rx_buf_ptr[rx_byte_tot - rx_byte_ctr] = UCB1RXBUF;
209 rx_byte_ctr--;
210 if(rx_byte_ctr == 1) { /* stop condition should be set before receiving last byte */
211 /* Only for 1-byte transmissions, STOP is handled in receive_n_int */
212 if(rx_byte_tot != 1) {
213 UCB1CTL1 |= UCTXSTP; /* I2C stop condition */
214 }
215 UC1IFG &= ~UCB1RXIFG; /* Clear USCI_B1 RX int flag. XXX Just in case, check if necessary */
216 }
217 }
218#endif
219}
220
221ISR(USCIAB1RX, i2c_rx_interrupt)
222{
223 if(UCB1STAT & UCNACKIFG) {
224 PRINTFDEBUG("!!! NACK received in RX\n");
225 UCB1CTL1 |= UCTXSTP;
226 UCB1STAT &= ~UCNACKIFG;
227 }
228}
I2C communication device driver header file for Zolertia Z1 sensor node.