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/* mbed Microcontroller Library
* Copyright (c) 2006-2013 ARM Limited
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "mbed_assert.h"
#include "i2c_api.h"
#include "cmsis.h"
#include "pinmap.h"
static uint8_t repeated_start = 0;
#define I2C_STAT(x) ((LPC_I2C0->STAT >> 1) & (0x07))
static inline int i2c_status(i2c_t *obj) {
return I2C_STAT(obj);
}
// Wait until the Serial Interrupt (SI) is set
static int i2c_wait_SI(i2c_t *obj) {
volatile int timeout = 0;
while (!(LPC_I2C0->STAT & (1 << 0))) {
timeout++;
if (timeout > 100000) return -1;
}
return 0;
}
static inline void i2c_interface_enable(i2c_t *obj) {
LPC_I2C0->CFG |= (1 << 0);
}
void i2c_init(i2c_t *obj, PinName sda, PinName scl) {
MBED_ASSERT((sda == P0_23) && (scl == P0_22));
// Enables clock for I2C0
LPC_SYSCON->SYSAHBCLKCTRL1 |= (1 << 13);
LPC_SYSCON->PRESETCTRL1 |= (1 << 13);
LPC_SYSCON->PRESETCTRL1 &= ~(1 << 13);
// pin enable
LPC_SWM->PINENABLE1 &= ~(0x3 << 3);
// set default frequency at 100kHz
i2c_frequency(obj, 100000);
i2c_interface_enable(obj);
}
inline int i2c_start(i2c_t *obj) {
int status = 0;
if (repeated_start) {
LPC_I2C0->MSTCTL = (1 << 1) | (1 << 0);
repeated_start = 0;
} else {
LPC_I2C0->MSTCTL = (1 << 1);
}
return status;
}
inline int i2c_stop(i2c_t *obj) {
volatile int timeout = 0;
LPC_I2C0->MSTCTL = (1 << 2) | (1 << 0);
while ((LPC_I2C0->STAT & ((1 << 0) | (7 << 1))) != ((1 << 0) | (0 << 1))) {
timeout ++;
if (timeout > 100000) return 1;
}
return 0;
}
static inline int i2c_do_write(i2c_t *obj, int value, uint8_t addr) {
// write the data
LPC_I2C0->MSTDAT = value;
if (!addr)
LPC_I2C0->MSTCTL = (1 << 0);
// wait and return status
i2c_wait_SI(obj);
return i2c_status(obj);
}
static inline int i2c_do_read(i2c_t *obj, int last) {
// wait for it to arrive
i2c_wait_SI(obj);
if (!last)
LPC_I2C0->MSTCTL = (1 << 0);
// return the data
return (LPC_I2C0->MSTDAT & 0xFF);
}
void i2c_frequency(i2c_t *obj, int hz) {
// No peripheral clock divider on the M0
uint32_t PCLK = SystemCoreClock;
uint32_t clkdiv = PCLK / (hz * 4) - 1;
LPC_I2C0->DIV = clkdiv;
LPC_I2C0->MSTTIME = 0;
}
int i2c_read(i2c_t *obj, int address, char *data, int length, int stop) {
int count, status;
i2c_start(obj);
LPC_I2C0->MSTDAT = (address | 0x01);
LPC_I2C0->MSTCTL |= 0x20;
if (i2c_wait_SI(obj) == -1)
return -1;
status = ((LPC_I2C0->STAT >> 1) & (0x07));
if (status != 0x01) {
i2c_stop(obj);
return I2C_ERROR_NO_SLAVE;
}
// Read in all except last byte
for (count = 0; count < (length - 1); count++) {
if (i2c_wait_SI(obj) == -1)
return -1;
LPC_I2C0->MSTCTL = (1 << 0);
data[count] = (LPC_I2C0->MSTDAT & 0xFF);
status = ((LPC_I2C0->STAT >> 1) & (0x07));
if (status != 0x01) {
i2c_stop(obj);
return count;
}
}
// read in last byte
if (i2c_wait_SI(obj) == -1)
return -1;
data[count] = (LPC_I2C0->MSTDAT & 0xFF);
status = i2c_status(obj);
if (status != 0x01) {
i2c_stop(obj);
return length - 1;
}
// If not repeated start, send stop.
if (stop) {
i2c_stop(obj);
} else {
repeated_start = 1;
}
return length;
}
int i2c_write(i2c_t *obj, int address, const char *data, int length, int stop) {
int i, status;
i2c_start(obj);
LPC_I2C0->MSTDAT = (address & 0xFE);
LPC_I2C0->MSTCTL |= 0x20;
if (i2c_wait_SI(obj) == -1)
return -1;
status = ((LPC_I2C0->STAT >> 1) & (0x07));
if (status != 0x02) {
i2c_stop(obj);
return I2C_ERROR_NO_SLAVE;
}
for (i=0; i<length; i++) {
LPC_I2C0->MSTDAT = data[i];
LPC_I2C0->MSTCTL = (1 << 0);
if (i2c_wait_SI(obj) == -1)
return -1;
status = ((LPC_I2C0->STAT >> 1) & (0x07));
if (status != 0x02) {
i2c_stop(obj);
return i;
}
}
// If not repeated start, send stop.
if (stop) {
i2c_stop(obj);
} else {
repeated_start = 1;
}
return length;
}
void i2c_reset(i2c_t *obj) {
i2c_stop(obj);
}
int i2c_byte_read(i2c_t *obj, int last) {
return (i2c_do_read(obj, last) & 0xFF);
}
int i2c_byte_write(i2c_t *obj, int data) {
if (i2c_do_write(obj, (data & 0xFF), 0) == 2) {
return 1;
} else {
return 0;
}
}
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