Filip Richter / eMPL_MPU6050

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mbed_i2c.c@1:6aedb937cb38, 2015-11-05 (annotated)

Committer:
yihui
Date:
Thu Nov 05 01:38:50 2015 +0000
Revision:
1:6aedb937cb38
Parent:
0:1b6dab73c06b 
add mbed_i2c_clear() function; ; use mbed_i2c_clear to recover i2c bus when i2c is stuck

Who changed what in which revision?

UserRevisionLine numberNew contents of line
yihui 0:1b6dab73c06b 1
yihui 1:6aedb937cb38 2 #include <stdio.h>
yihui 0:1b6dab73c06b 3 #include "i2c_api.h"
yihui 1:6aedb937cb38 4 #include "gpio_api.h"
yihui 1:6aedb937cb38 5 #include "nrf_delay.h"
yihui 0:1b6dab73c06b 6
yihui 1:6aedb937cb38 7 static i2c_t mbed_i2c_object = {0,};
yihui 0:1b6dab73c06b 8
yihui 0:1b6dab73c06b 9 void mbed_i2c_init(PinName sda, PinName scl)
yihui 0:1b6dab73c06b 10 {
yihui 0:1b6dab73c06b 11 i2c_init(&mbed_i2c_object, sda, scl);
yihui 0:1b6dab73c06b 12 i2c_frequency(&mbed_i2c_object, 100000);
yihui 0:1b6dab73c06b 13 }
yihui 0:1b6dab73c06b 14
yihui 0:1b6dab73c06b 15 int mbed_i2c_write(unsigned char slave_addr,
yihui 0:1b6dab73c06b 16 unsigned char reg_addr,
yihui 0:1b6dab73c06b 17 unsigned char length,
yihui 0:1b6dab73c06b 18 unsigned char const *data)
yihui 0:1b6dab73c06b 19 {
yihui 0:1b6dab73c06b 20 int i;
yihui 0:1b6dab73c06b 21 slave_addr = slave_addr << 1;
yihui 0:1b6dab73c06b 22 i2c_start(&mbed_i2c_object);
yihui 0:1b6dab73c06b 23 i2c_byte_write(&mbed_i2c_object, slave_addr);
yihui 0:1b6dab73c06b 24 i2c_byte_write(&mbed_i2c_object, reg_addr);
yihui 0:1b6dab73c06b 25 for (i = 0; i < length; i++) {
yihui 0:1b6dab73c06b 26 i2c_byte_write(&mbed_i2c_object, data[i]);
yihui 0:1b6dab73c06b 27 }
yihui 0:1b6dab73c06b 28 i2c_stop(&mbed_i2c_object);
yihui 0:1b6dab73c06b 29 return 0;
yihui 0:1b6dab73c06b 30 }
yihui 0:1b6dab73c06b 31
yihui 0:1b6dab73c06b 32 int mbed_i2c_read(unsigned char slave_addr,
yihui 0:1b6dab73c06b 33 unsigned char reg_addr,
yihui 0:1b6dab73c06b 34 unsigned char length,
yihui 0:1b6dab73c06b 35 unsigned char *data)
yihui 0:1b6dab73c06b 36 {
yihui 0:1b6dab73c06b 37 slave_addr = slave_addr << 1;
yihui 0:1b6dab73c06b 38 i2c_write(&mbed_i2c_object, slave_addr, &reg_addr, 1, 0);
yihui 0:1b6dab73c06b 39 return (i2c_read(&mbed_i2c_object, slave_addr, data, length, 1) == length) ? 0 : 1;
yihui 0:1b6dab73c06b 40 }
yihui 1:6aedb937cb38 41
yihui 1:6aedb937cb38 42 int mbed_i2c_clear(PinName sda, PinName scl)
yihui 1:6aedb937cb38 43 {
yihui 1:6aedb937cb38 44 gpio_t sda_io, scl_io;
yihui 1:6aedb937cb38 45
yihui 1:6aedb937cb38 46 if (mbed_i2c_object.i2c) {
yihui 1:6aedb937cb38 47 mbed_i2c_object.i2c->PSELSCL = 31;
yihui 1:6aedb937cb38 48 mbed_i2c_object.i2c->PSELSDA = 31;
yihui 1:6aedb937cb38 49 }
yihui 1:6aedb937cb38 50
yihui 1:6aedb937cb38 51 gpio_init_in(&sda_io, sda);
yihui 1:6aedb937cb38 52
yihui 1:6aedb937cb38 53 if (!gpio_read(&sda_io)) {
yihui 1:6aedb937cb38 54 printf("sda is always 0, i2c bus is not released\r\n");
yihui 1:6aedb937cb38 55 printf("try to clear i2c bus\r\n");
yihui 1:6aedb937cb38 56 gpio_init_out(&scl_io, scl);
yihui 1:6aedb937cb38 57
yihui 1:6aedb937cb38 58 // Clock max 18 pulses worst case scenario(9 for master to send the rest of command and 9
yihui 1:6aedb937cb38 59 // for slave to respond) to SCL line and wait for SDA come high.
yihui 1:6aedb937cb38 60 for (int i = 0; i < 18; i++) {
yihui 1:6aedb937cb38 61 gpio_write(&scl_io, 0);
yihui 1:6aedb937cb38 62 nrf_delay_us(4);
yihui 1:6aedb937cb38 63 gpio_write(&scl_io, 1);
yihui 1:6aedb937cb38 64 nrf_delay_us(4);
yihui 1:6aedb937cb38 65 }
yihui 1:6aedb937cb38 66
yihui 1:6aedb937cb38 67 if (!gpio_read(&sda_io)) {
yihui 1:6aedb937cb38 68 printf("warning! sda is still 0,, i2c bus is not released\r\n");
yihui 1:6aedb937cb38 69 }
yihui 1:6aedb937cb38 70 }
yihui 1:6aedb937cb38 71
yihui 1:6aedb937cb38 72
yihui 1:6aedb937cb38 73 if (mbed_i2c_object.i2c) {
yihui 1:6aedb937cb38 74 mbed_i2c_init(sda, scl);
yihui 1:6aedb937cb38 75 }
yihui 1:6aedb937cb38 76
yihui 1:6aedb937cb38 77 return 0;
yihui 1:6aedb937cb38 78 }