mbed library sources
Dependents: frdm_kl05z_gpio_test
Fork of mbed-src by
targets/hal/TARGET_NXP/TARGET_LPC81X/i2c_api.c
- Committer:
- shaoziyang
- Date:
- 2014-09-13
- Revision:
- 323:9e901b0a5aa1
- Parent:
- 227:7bd0639b8911
File content as of revision 323:9e901b0a5aa1:
/* 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 "i2c_api.h" #include "cmsis.h" #include "pinmap.h" static const SWM_Map SWM_I2C_SDA[] = { {7, 24}, }; static const SWM_Map SWM_I2C_SCL[] = { {8, 0}, }; static uint8_t repeated_start = 0; #define I2C_DAT(x) (x->i2c->MSTDAT) #define I2C_STAT(x) ((x->i2c->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) { int timeout = 0; while (!(obj->i2c->STAT & (1 << 0))) { timeout++; if (timeout > 100000) return -1; } return 0; } static inline void i2c_interface_enable(i2c_t *obj) { obj->i2c->CFG |= (1 << 0); } static inline void i2c_power_enable(i2c_t *obj) { LPC_SYSCON->SYSAHBCLKCTRL |= (1<<5); LPC_SYSCON->PRESETCTRL &= ~(0x1<<6); LPC_SYSCON->PRESETCTRL |= (0x1<<6); } void i2c_init(i2c_t *obj, PinName sda, PinName scl) { obj->i2c = (LPC_I2C_TypeDef *)LPC_I2C; const SWM_Map *swm; uint32_t regVal; swm = &SWM_I2C_SDA[0]; regVal = LPC_SWM->PINASSIGN[swm->n] & ~(0xFF << swm->offset); LPC_SWM->PINASSIGN[swm->n] = regVal | (sda << swm->offset); swm = &SWM_I2C_SCL[0]; regVal = LPC_SWM->PINASSIGN[swm->n] & ~(0xFF << swm->offset); LPC_SWM->PINASSIGN[swm->n] = regVal | (scl << swm->offset); // enable power i2c_power_enable(obj); // set default frequency at 100k i2c_frequency(obj, 100000); i2c_interface_enable(obj); } inline int i2c_start(i2c_t *obj) { int status = 0; if (repeated_start) { obj->i2c->MSTCTL = (1 << 1) | (1 << 0); repeated_start = 0; } else { obj->i2c->MSTCTL = (1 << 1); } return status; } inline int i2c_stop(i2c_t *obj) { int timeout = 0; obj->i2c->MSTCTL = (1 << 2) | (1 << 0); while ((obj->i2c->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 I2C_DAT(obj) = value; if (!addr) obj->i2c->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) obj->i2c->MSTCTL = (1 << 0); // return the data return (I2C_DAT(obj) & 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; obj->i2c->DIV = clkdiv; obj->i2c->MSTTIME = 0; } // The I2C does a read or a write as a whole operation // There are two types of error conditions it can encounter // 1) it can not obtain the bus // 2) it gets error responses at part of the transmission // // We tackle them as follows: // 1) we retry until we get the bus. we could have a "timeout" if we can not get it // which basically turns it in to a 2) // 2) on error, we use the standard error mechanisms to report/debug // // Therefore an I2C transaction should always complete. If it doesn't it is usually // because something is setup wrong (e.g. wiring), and we don't need to programatically // check for that int i2c_read(i2c_t *obj, int address, char *data, int length, int stop) { int count, status; i2c_start(obj); status = i2c_do_write(obj, (address | 0x01), 1); if (status != 0x01) { i2c_stop(obj); return I2C_ERROR_NO_SLAVE; } // Read in all except last byte for (count = 0; count < (length - 1); count++) { int value = i2c_do_read(obj, 0); status = i2c_status(obj); if (status != 0x00) { i2c_stop(obj); return count; } data[count] = (char) value; } // read in last byte int value = i2c_do_read(obj, 1); status = i2c_status(obj); if (status != 0x01) { i2c_stop(obj); return length - 1; } data[count] = (char) value; // 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); status = i2c_do_write(obj, (address & 0xFE), 1); if (status != 0x02) { i2c_stop(obj); return I2C_ERROR_NO_SLAVE; } for (i=0; i<length; i++) { status = i2c_do_write(obj, data[i], 0); 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) { int ack; int status = i2c_do_write(obj, (data & 0xFF), 0); switch(status) { case 2: ack = 1; break; default: ack = 0; break; } return ack; }