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"
20 #include "mbed_error.h"
22 static const PinMap PinMap_I2C_SDA[] = {
27 static const PinMap PinMap_I2C_SCL[] = {
32 #define I2C_CONSET(x) (x->i2c->CONSET)
33 #define I2C_CONCLR(x) (x->i2c->CONCLR)
34 #define I2C_STAT(x) (x->i2c->STAT)
35 #define I2C_DAT(x) (x->i2c->DAT)
36 #define I2C_SCLL(x, val) (x->i2c->SCLL = val)
37 #define I2C_SCLH(x, val) (x->i2c->SCLH = val)
39 static const uint32_t I2C_addr_offset[2][4] = {
40 {0x0C, 0x20, 0x24, 0x28},
41 {0x30, 0x34, 0x38, 0x3C}
44 static inline void i2c_conclr(i2c_t *obj, int start, int stop, int interrupt, int acknowledge) {
45 I2C_CONCLR(obj) = (start << 5)
51 static inline void i2c_conset(i2c_t *obj, int start, int stop, int interrupt, int acknowledge) {
52 I2C_CONSET(obj) = (start << 5)
58 // Clear the Serial Interrupt (SI)
59 static inline void i2c_clear_SI(i2c_t *obj) {
60 i2c_conclr(obj, 0, 0, 1, 0);
63 static inline int i2c_status(i2c_t *obj) {
67 // Wait until the Serial Interrupt (SI) is set
68 static int i2c_wait_SI(i2c_t *obj) {
70 while (!(I2C_CONSET(obj) & (1 << 3))) {
72 if (timeout > 100000) return -1;
77 static inline void i2c_interface_enable(i2c_t *obj) {
78 I2C_CONSET(obj) = 0x40;
81 static inline void i2c_power_enable(i2c_t *obj) {
82 LPC_SYSCON->SYSAHBCLKCTRL |= (1 << 5);
83 LPC_SYSCON->PRESETCTRL |= 1 << 1;
86 void i2c_init(i2c_t *obj, PinName sda, PinName scl) {
87 // determine the SPI to use
88 I2CName i2c_sda = (I2CName)pinmap_peripheral(sda, PinMap_I2C_SDA);
89 I2CName i2c_scl = (I2CName)pinmap_peripheral(scl, PinMap_I2C_SCL);
90 obj->i2c = (LPC_I2C_TypeDef *)pinmap_merge(i2c_sda, i2c_scl);
91 MBED_ASSERT((int)obj->i2c != NC);
94 i2c_power_enable(obj);
96 // set default frequency at 100k
97 i2c_frequency(obj, 100000);
98 i2c_conclr(obj, 1, 1, 1, 1);
99 i2c_interface_enable(obj);
101 pinmap_pinout(sda, PinMap_I2C_SDA);
102 pinmap_pinout(scl, PinMap_I2C_SCL);
105 inline int i2c_start(i2c_t *obj) {
107 // 8.1 Before master mode can be entered, I2CON must be initialised to:
108 // - I2EN STA STO SI AA - -
110 // if AA = 0, it can't enter slave mode
111 i2c_conclr(obj, 1, 1, 1, 1);
113 // The master mode may now be entered by setting the STA bit
114 // this will generate a start condition when the bus becomes free
115 i2c_conset(obj, 1, 0, 0, 1);
118 status = i2c_status(obj);
120 // Clear start bit now transmitted, and interrupt bit
121 i2c_conclr(obj, 1, 0, 0, 0);
125 inline int i2c_stop(i2c_t *obj) {
128 // write the stop bit
129 i2c_conset(obj, 0, 1, 0, 0);
132 // wait for STO bit to reset
133 while(I2C_CONSET(obj) & (1 << 4)) {
135 if (timeout > 100000) return 1;
142 static inline int i2c_do_write(i2c_t *obj, int value, uint8_t addr) {
144 I2C_DAT(obj) = value;
146 // clear SI to init a send
149 // wait and return status
151 return i2c_status(obj);
154 static inline int i2c_do_read(i2c_t *obj, int last) {
155 // we are in state 0x40 (SLA+R tx'd) or 0x50 (data rx'd and ack)
157 i2c_conclr(obj, 0, 0, 0, 1); // send a NOT ACK
159 i2c_conset(obj, 0, 0, 0, 1); // send a ACK
165 // wait for it to arrive
169 return (I2C_DAT(obj) & 0xFF);
172 void i2c_frequency(i2c_t *obj, int hz) {
173 // No peripheral clock divider on the M0
174 uint32_t PCLK = SystemCoreClock;
176 uint32_t pulse = PCLK / (hz * 2);
179 I2C_SCLL(obj, pulse);
180 I2C_SCLH(obj, pulse);
183 // The I2C does a read or a write as a whole operation
184 // There are two types of error conditions it can encounter
185 // 1) it can not obtain the bus
186 // 2) it gets error responses at part of the transmission
188 // We tackle them as follows:
189 // 1) we retry until we get the bus. we could have a "timeout" if we can not get it
190 // which basically turns it in to a 2)
191 // 2) on error, we use the standard error mechanisms to report/debug
193 // Therefore an I2C transaction should always complete. If it doesn't it is usually
194 // because something is setup wrong (e.g. wiring), and we don't need to programatically
197 int i2c_read(i2c_t *obj, int address, char *data, int length, int stop) {
200 status = i2c_start(obj);
202 if ((status != 0x10) && (status != 0x08)) {
204 return I2C_ERROR_BUS_BUSY;
207 status = i2c_do_write(obj, (address | 0x01), 1);
208 if (status != 0x40) {
210 return I2C_ERROR_NO_SLAVE;
213 // Read in all except last byte
214 for (count = 0; count < (length - 1); count++) {
215 int value = i2c_do_read(obj, 0);
216 status = i2c_status(obj);
217 if (status != 0x50) {
221 data[count] = (char) value;
225 int value = i2c_do_read(obj, 1);
226 status = i2c_status(obj);
227 if (status != 0x58) {
232 data[count] = (char) value;
234 // If not repeated start, send stop.
242 int i2c_write(i2c_t *obj, int address, const char *data, int length, int stop) {
245 status = i2c_start(obj);
247 if ((status != 0x10) && (status != 0x08)) {
249 return I2C_ERROR_BUS_BUSY;
252 status = i2c_do_write(obj, (address & 0xFE), 1);
253 if (status != 0x18) {
255 return I2C_ERROR_NO_SLAVE;
258 for (i=0; i<length; i++) {
259 status = i2c_do_write(obj, data[i], 0);
266 // clearing the serial interrupt here might cause an unintended rewrite of the last byte
267 // see also issue report https://mbed.org/users/mbed_official/code/mbed/issues/1
268 // i2c_clear_SI(obj);
270 // If not repeated start, send stop.
278 void i2c_reset(i2c_t *obj) {
282 int i2c_byte_read(i2c_t *obj, int last) {
283 return (i2c_do_read(obj, last) & 0xFF);
286 int i2c_byte_write(i2c_t *obj, int data) {
288 int status = i2c_do_write(obj, (data & 0xFF), 0);
291 case 0x18: case 0x28: // Master transmit ACKs
294 case 0x40: // Master receive address transmitted ACK
297 case 0xB8: // Slave transmit ACK
308 void i2c_slave_mode(i2c_t *obj, int enable_slave) {
309 if (enable_slave != 0) {
310 i2c_conclr(obj, 1, 1, 1, 0);
311 i2c_conset(obj, 0, 0, 0, 1);
313 i2c_conclr(obj, 1, 1, 1, 1);
317 int i2c_slave_receive(i2c_t *obj) {
321 status = i2c_status(obj);
323 case 0x60: retval = 3; break;
324 case 0x70: retval = 2; break;
325 case 0xA8: retval = 1; break;
326 default : retval = 0; break;
332 int i2c_slave_read(i2c_t *obj, char *data, int length) {
339 status = i2c_status(obj);
340 if((status == 0x80) || (status == 0x90)) {
341 data[count] = I2C_DAT(obj) & 0xFF;
344 } while (((status == 0x80) || (status == 0x90) ||
345 (status == 0x060) || (status == 0x70)) && (count < length));
356 int i2c_slave_write(i2c_t *obj, const char *data, int length) {
365 status = i2c_do_write(obj, data[count], 0);
367 } while ((count < length) && (status == 0xB8));
369 if((status != 0xC0) && (status != 0xC8)) {
378 void i2c_slave_address(i2c_t *obj, int idx, uint32_t address, uint32_t mask) {
381 if ((idx >= 0) && (idx <= 3)) {
382 addr = ((uint32_t)obj->i2c) + I2C_addr_offset[0][idx];
383 *((uint32_t *) addr) = address & 0xFF;
384 addr = ((uint32_t)obj->i2c) + I2C_addr_offset[1][idx];
385 *((uint32_t *) addr) = mask & 0xFE;