Yihui Xiong / eMPL_MPU

library for MPU6050 and MPU9250, supports both I2C and SPI

Dependents:   Seeed_nRF51822_MPU9250

mbed_i2c.c@0:972f3778c19c, 2015-12-10 (annotated)

Committer:
yihui
Date:
Thu Dec 10 07:39:48 2015 +0000
Revision:
0:972f3778c19c
initial

Who changed what in which revision?

UserRevisionLine numberNew contents of line
yihui 0:972f3778c19c 1
yihui 0:972f3778c19c 2 #include <stdio.h>
yihui 0:972f3778c19c 3 #include "i2c_api.h"
yihui 0:972f3778c19c 4 #include "gpio_api.h"
yihui 0:972f3778c19c 5 #include "nrf_delay.h"
yihui 0:972f3778c19c 6
yihui 0:972f3778c19c 7 static i2c_t mbed_i2c_object = {0,};
yihui 0:972f3778c19c 8 PinName mbed_i2c_sda_pin = NC;
yihui 0:972f3778c19c 9 PinName mbed_i2c_scl_pin = NC;
yihui 0:972f3778c19c 10
yihui 0:972f3778c19c 11 void mbed_i2c_init(PinName sda, PinName scl)
yihui 0:972f3778c19c 12 {
yihui 0:972f3778c19c 13 if (mbed_i2c_sda_pin == NC) {
yihui 0:972f3778c19c 14 mbed_i2c_sda_pin = sda;
yihui 0:972f3778c19c 15 mbed_i2c_scl_pin = scl;
yihui 0:972f3778c19c 16 }
yihui 0:972f3778c19c 17
yihui 0:972f3778c19c 18 i2c_init(&mbed_i2c_object, sda, scl);
yihui 0:972f3778c19c 19 i2c_frequency(&mbed_i2c_object, 100000);
yihui 0:972f3778c19c 20 }
yihui 0:972f3778c19c 21
yihui 0:972f3778c19c 22 int mbed_i2c_write(unsigned char slave_addr,
yihui 0:972f3778c19c 23 unsigned char reg_addr,
yihui 0:972f3778c19c 24 unsigned char length,
yihui 0:972f3778c19c 25 unsigned char const *data)
yihui 0:972f3778c19c 26 {
yihui 0:972f3778c19c 27 int i;
yihui 0:972f3778c19c 28 slave_addr = slave_addr << 1;
yihui 0:972f3778c19c 29 i2c_start(&mbed_i2c_object);
yihui 0:972f3778c19c 30 i2c_byte_write(&mbed_i2c_object, slave_addr);
yihui 0:972f3778c19c 31 i2c_byte_write(&mbed_i2c_object, reg_addr);
yihui 0:972f3778c19c 32 for (i = 0; i < length; i++) {
yihui 0:972f3778c19c 33 i2c_byte_write(&mbed_i2c_object, data[i]);
yihui 0:972f3778c19c 34 }
yihui 0:972f3778c19c 35 i2c_stop(&mbed_i2c_object);
yihui 0:972f3778c19c 36 return 0;
yihui 0:972f3778c19c 37 }
yihui 0:972f3778c19c 38
yihui 0:972f3778c19c 39 int mbed_i2c_read(unsigned char slave_addr,
yihui 0:972f3778c19c 40 unsigned char reg_addr,
yihui 0:972f3778c19c 41 unsigned char length,
yihui 0:972f3778c19c 42 unsigned char *data)
yihui 0:972f3778c19c 43 {
yihui 0:972f3778c19c 44 slave_addr = slave_addr << 1;
yihui 0:972f3778c19c 45 i2c_write(&mbed_i2c_object, slave_addr, &reg_addr, 1, 0);
yihui 0:972f3778c19c 46 return (i2c_read(&mbed_i2c_object, slave_addr, data, length, 1) == length) ? 0 : 1;
yihui 0:972f3778c19c 47 }
yihui 0:972f3778c19c 48
yihui 0:972f3778c19c 49 int mbed_i2c_clear(PinName sda, PinName scl)
yihui 0:972f3778c19c 50 {
yihui 0:972f3778c19c 51 gpio_t sda_io, scl_io;
yihui 0:972f3778c19c 52
yihui 0:972f3778c19c 53 if (mbed_i2c_object.i2c) {
yihui 0:972f3778c19c 54 mbed_i2c_object.i2c->PSELSCL = 31;
yihui 0:972f3778c19c 55 mbed_i2c_object.i2c->PSELSDA = 31;
yihui 0:972f3778c19c 56 }
yihui 0:972f3778c19c 57
yihui 0:972f3778c19c 58 gpio_init_in(&sda_io, sda);
yihui 0:972f3778c19c 59
yihui 0:972f3778c19c 60 if (!gpio_read(&sda_io)) {
yihui 0:972f3778c19c 61 printf("sda is always 0, i2c bus is not released\r\n");
yihui 0:972f3778c19c 62 printf("try to clear i2c bus\r\n");
yihui 0:972f3778c19c 63 gpio_init_out(&scl_io, scl);
yihui 0:972f3778c19c 64
yihui 0:972f3778c19c 65 // Clock max 18 pulses worst case scenario(9 for master to send the rest of command and 9
yihui 0:972f3778c19c 66 // for slave to respond) to SCL line and wait for SDA come high.
yihui 0:972f3778c19c 67 for (int i = 0; i < 18; i++) {
yihui 0:972f3778c19c 68 gpio_write(&scl_io, 0);
yihui 0:972f3778c19c 69 nrf_delay_us(4);
yihui 0:972f3778c19c 70 gpio_write(&scl_io, 1);
yihui 0:972f3778c19c 71 nrf_delay_us(4);
yihui 0:972f3778c19c 72 }
yihui 0:972f3778c19c 73
yihui 0:972f3778c19c 74 if (!gpio_read(&sda_io)) {
yihui 0:972f3778c19c 75 printf("warning! sda is still 0,, i2c bus is not released\r\n");
yihui 0:972f3778c19c 76 }
yihui 0:972f3778c19c 77 }
yihui 0:972f3778c19c 78
yihui 0:972f3778c19c 79
yihui 0:972f3778c19c 80 if (mbed_i2c_object.i2c) {
yihui 0:972f3778c19c 81 mbed_i2c_init(sda, scl);
yihui 0:972f3778c19c 82 }
yihui 0:972f3778c19c 83
yihui 0:972f3778c19c 84 return 0;
yihui 0:972f3778c19c 85 }
yihui 0:972f3778c19c 86
yihui 0:972f3778c19c 87 void mbed_i2c_enable(void)
yihui 0:972f3778c19c 88 {
yihui 0:972f3778c19c 89 mbed_i2c_object.i2c->POWER = 1;
yihui 0:972f3778c19c 90
yihui 0:972f3778c19c 91 mbed_i2c_init(mbed_i2c_sda_pin, mbed_i2c_scl_pin);
yihui 0:972f3778c19c 92 }
yihui 0:972f3778c19c 93
yihui 0:972f3778c19c 94 void mbed_i2c_disable(void)
yihui 0:972f3778c19c 95 {
yihui 0:972f3778c19c 96 gpio_t sda_io, scl_io;
yihui 0:972f3778c19c 97
yihui 0:972f3778c19c 98 mbed_i2c_object.i2c->PSELSCL = 31;
yihui 0:972f3778c19c 99 mbed_i2c_object.i2c->PSELSDA = 31;
yihui 0:972f3778c19c 100
yihui 0:972f3778c19c 101
yihui 0:972f3778c19c 102 mbed_i2c_object.i2c->ENABLE = TWI_ENABLE_ENABLE_Disabled << TWI_ENABLE_ENABLE_Pos;
yihui 0:972f3778c19c 103 mbed_i2c_object.i2c->POWER = 0;
yihui 0:972f3778c19c 104
yihui 0:972f3778c19c 105 gpio_init_in(&sda_io, mbed_i2c_sda_pin);
yihui 0:972f3778c19c 106 gpio_init_in(&scl_io, mbed_i2c_scl_pin);
yihui 0:972f3778c19c 107 }