1 /* mbed Microcontroller Library
2 * Copyright (c) 2006-2013 ARM Limited
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
16 #include "mbed_assert.h"
21 static const PinMap PinMap_I2C_SDA[] = {
29 static const PinMap PinMap_I2C_SCL[] = {
37 #define I2C_CONSET(x) (x->i2c->I2CONSET)
38 #define I2C_CONCLR(x) (x->i2c->I2CONCLR)
39 #define I2C_STAT(x) (x->i2c->I2STAT)
40 #define I2C_DAT(x) (x->i2c->I2DAT)
41 #define I2C_SCLL(x, val) (x->i2c->I2SCLL = val)
42 #define I2C_SCLH(x, val) (x->i2c->I2SCLH = val)
44 static const uint32_t I2C_addr_offset[2][4] = {
45 {0x0C, 0x20, 0x24, 0x28},
46 {0x30, 0x34, 0x38, 0x3C}
49 static inline void i2c_conclr(i2c_t *obj, int start, int stop, int interrupt, int acknowledge) {
50 I2C_CONCLR(obj) = (start << 5)
56 static inline void i2c_conset(i2c_t *obj, int start, int stop, int interrupt, int acknowledge) {
57 I2C_CONSET(obj) = (start << 5)
63 // Clear the Serial Interrupt (SI)
64 static inline void i2c_clear_SI(i2c_t *obj) {
65 i2c_conclr(obj, 0, 0, 1, 0);
68 static inline int i2c_status(i2c_t *obj) {
72 // Wait until the Serial Interrupt (SI) is set
73 static int i2c_wait_SI(i2c_t *obj) {
75 while (!(I2C_CONSET(obj) & (1 << 3))) {
77 if (timeout > 100000) return -1;
82 static inline void i2c_interface_enable(i2c_t *obj) {
83 I2C_CONSET(obj) = 0x40;
86 static inline void i2c_power_enable(i2c_t *obj) {
87 switch ((int)obj->i2c) {
88 case I2C_0: LPC_SC->PCONP |= 1 << 7; break;
89 case I2C_1: LPC_SC->PCONP |= 1 << 19; break;
90 case I2C_2: LPC_SC->PCONP |= 1 << 26; break;
94 void i2c_init(i2c_t *obj, PinName sda, PinName scl) {
95 // determine the SPI to use
96 I2CName i2c_sda = (I2CName)pinmap_peripheral(sda, PinMap_I2C_SDA);
97 I2CName i2c_scl = (I2CName)pinmap_peripheral(scl, PinMap_I2C_SCL);
98 obj->i2c = (LPC_I2C_TypeDef *)pinmap_merge(i2c_sda, i2c_scl);
99 MBED_ASSERT((int)obj->i2c != NC);
102 i2c_power_enable(obj);
104 // set default frequency at 100k
105 i2c_frequency(obj, 100000);
106 i2c_conclr(obj, 1, 1, 1, 1);
107 i2c_interface_enable(obj);
109 pinmap_pinout(sda, PinMap_I2C_SDA);
110 pinmap_pinout(scl, PinMap_I2C_SCL);
113 inline int i2c_start(i2c_t *obj) {
115 // 8.1 Before master mode can be entered, I2CON must be initialised to:
116 // - I2EN STA STO SI AA - -
118 // if AA = 0, it can't enter slave mode
119 i2c_conclr(obj, 1, 1, 1, 1);
121 // The master mode may now be entered by setting the STA bit
122 // this will generate a start condition when the bus becomes free
123 i2c_conset(obj, 1, 0, 0, 1);
126 status = i2c_status(obj);
128 // Clear start bit now transmitted, and interrupt bit
129 i2c_conclr(obj, 1, 0, 0, 0);
133 inline int i2c_stop(i2c_t *obj) {
136 // write the stop bit
137 i2c_conset(obj, 0, 1, 0, 0);
140 // wait for STO bit to reset
141 while(I2C_CONSET(obj) & (1 << 4)) {
143 if (timeout > 100000) return 1;
149 static inline int i2c_do_write(i2c_t *obj, int value, uint8_t addr) {
151 I2C_DAT(obj) = value;
153 // clear SI to init a send
156 // wait and return status
158 return i2c_status(obj);
161 static inline int i2c_do_read(i2c_t *obj, int last) {
162 // we are in state 0x40 (SLA+R tx'd) or 0x50 (data rx'd and ack)
164 i2c_conclr(obj, 0, 0, 0, 1); // send a NOT ACK
166 i2c_conset(obj, 0, 0, 0, 1); // send a ACK
172 // wait for it to arrive
176 return (I2C_DAT(obj) & 0xFF);
179 void i2c_frequency(i2c_t *obj, int hz) {
180 // [TODO] set pclk to /4
181 uint32_t PCLK = SystemCoreClock / 4;
183 uint32_t pulse = PCLK / (hz * 2);
186 I2C_SCLL(obj, pulse);
187 I2C_SCLH(obj, pulse);
190 // The I2C does a read or a write as a whole operation
191 // There are two types of error conditions it can encounter
192 // 1) it can not obtain the bus
193 // 2) it gets error responses at part of the transmission
195 // We tackle them as follows:
196 // 1) we retry until we get the bus. we could have a "timeout" if we can not get it
197 // which basically turns it in to a 2)
198 // 2) on error, we use the standard error mechanisms to report/debug
200 // Therefore an I2C transaction should always complete. If it doesn't it is usually
201 // because something is setup wrong (e.g. wiring), and we don't need to programatically
204 int i2c_read(i2c_t *obj, int address, char *data, int length, int stop) {
207 status = i2c_start(obj);
209 if ((status != 0x10) && (status != 0x08)) {
211 return I2C_ERROR_BUS_BUSY;
214 status = i2c_do_write(obj, (address | 0x01), 1);
215 if (status != 0x40) {
217 return I2C_ERROR_NO_SLAVE;
220 // Read in all except last byte
221 for (count = 0; count < (length - 1); count++) {
222 int value = i2c_do_read(obj, 0);
223 status = i2c_status(obj);
224 if (status != 0x50) {
228 data[count] = (char) value;
232 int value = i2c_do_read(obj, 1);
233 status = i2c_status(obj);
234 if (status != 0x58) {
239 data[count] = (char) value;
241 // If not repeated start, send stop.
249 int i2c_write(i2c_t *obj, int address, const char *data, int length, int stop) {
252 status = i2c_start(obj);
254 if ((status != 0x10) && (status != 0x08)) {
256 return I2C_ERROR_BUS_BUSY;
259 status = i2c_do_write(obj, (address & 0xFE), 1);
260 if (status != 0x18) {
262 return I2C_ERROR_NO_SLAVE;
265 for (i=0; i<length; i++) {
266 status = i2c_do_write(obj, data[i], 0);
273 // clearing the serial interrupt here might cause an unintended rewrite of the last byte
274 // see also issue report https://mbed.org/users/mbed_official/code/mbed/issues/1
275 // i2c_clear_SI(obj);
277 // If not repeated start, send stop.
285 void i2c_reset(i2c_t *obj) {
289 int i2c_byte_read(i2c_t *obj, int last) {
290 return (i2c_do_read(obj, last) & 0xFF);
293 int i2c_byte_write(i2c_t *obj, int data) {
295 int status = i2c_do_write(obj, (data & 0xFF), 0);
298 case 0x18: case 0x28: // Master transmit ACKs
301 case 0x40: // Master receive address transmitted ACK
304 case 0xB8: // Slave transmit ACK
315 void i2c_slave_mode(i2c_t *obj, int enable_slave) {
316 if (enable_slave != 0) {
317 i2c_conclr(obj, 1, 1, 1, 0);
318 i2c_conset(obj, 0, 0, 0, 1);
320 i2c_conclr(obj, 1, 1, 1, 1);
324 int i2c_slave_receive(i2c_t *obj) {
328 status = i2c_status(obj);
330 case 0x60: retval = 3; break;
331 case 0x70: retval = 2; break;
332 case 0xA8: retval = 1; break;
333 default : retval = 0; break;
339 int i2c_slave_read(i2c_t *obj, char *data, int length) {
346 status = i2c_status(obj);
347 if((status == 0x80) || (status == 0x90)) {
348 data[count] = I2C_DAT(obj) & 0xFF;
351 } while (((status == 0x80) || (status == 0x90) ||
352 (status == 0x060) || (status == 0x70)) && (count < length));
363 int i2c_slave_write(i2c_t *obj, const char *data, int length) {
372 status = i2c_do_write(obj, data[count], 0);
374 } while ((count < length) && (status == 0xB8));
376 if ((status != 0xC0) && (status != 0xC8)) {
385 void i2c_slave_address(i2c_t *obj, int idx, uint32_t address, uint32_t mask) {
388 if ((idx >= 0) && (idx <= 3)) {
389 addr = ((uint32_t)obj->i2c) + I2C_addr_offset[0][idx];
390 *((uint32_t *) addr) = address & 0xFF;
391 addr = ((uint32_t)obj->i2c) + I2C_addr_offset[1][idx];
392 *((uint32_t *) addr) = mask & 0xFE;