Rodrigo Almeida / pqdb

Pão de Queijo Development Board. This repo has all libraries from pqdb shield.

Dependents:   pqdb_demo

Pão de Queijo development board is a shield for add-on on any arduino compatible board.

/media/uploads/rmaalmeida/compatibilidade_branco.png

This project presents the libraries to control the board peripherals using mbed framework. The libraries works as interfaces to keep the main code compatible with the examples from the book "Programação de sistemas embarcados". The peripherals on the board are presented on the folowing picture

/media/uploads/rmaalmeida/pqdb_perifericos.png

The main objective of the project is to develop a low cost, easy to assemble board with a group of peripheral that allows one to start learning embedded systems. The board was routed on one side copper PCB to make easier to buid it yourself.

/media/uploads/rmaalmeida/pqdb_fenolite_-_cortada.png

The source code for Arduino boards (wiring) can be found on: https://github.com/projetopqdb/PQDB-Arduino

The source code for freedom frdm KL05 board (using direct register access) can be found on: https://github.com/projetopqdb/PQDB-KL05Z

The source code from the board schematics and layout can be found on: https://github.com/projetopqdb/PQDB-Hardware

i2c.cpp@6:3fb450ba1e95, 2017-10-03 (annotated)

Committer:
rmaalmeida
Date:
Tue Oct 03 01:27:24 2017 +0000
Revision:
6:3fb450ba1e95
Parent:
3:6ca4d7dd8bea 
timer driver added

Who changed what in which revision?

UserRevisionLine numberNew contents of line
rmaalmeida 2:4b7f5a060c22 1 #include "i2c.h"
rmaalmeida 2:4b7f5a060c22 2 //#include "io.h"
rmaalmeida 2:4b7f5a060c22 3 #include "mbed.h"
rmaalmeida 2:4b7f5a060c22 4
rmaalmeida 2:4b7f5a060c22 5 /*
rmaalmeida 2:4b7f5a060c22 6 #define SDA_OFF() digitalWrite(SDA_PIN,LOW)
rmaalmeida 2:4b7f5a060c22 7 #define SDA() digitalRead(SDA_PIN)
rmaalmeida 2:4b7f5a060c22 8 #define SDA_IN() pinMode(SDA_PIN,INPUT)
rmaalmeida 2:4b7f5a060c22 9 #define SDA_OUT() pinMode(SDA_PIN,OUTPUT)
rmaalmeida 2:4b7f5a060c22 10
rmaalmeida 2:4b7f5a060c22 11 #define SCL_OFF() digitalWrite(SCL_PIN,LOW)
rmaalmeida 2:4b7f5a060c22 12 #define SCL() digitalRead(SCL_PIN)
rmaalmeida 2:4b7f5a060c22 13 #define SCL_IN() pinMode(SCL_PIN,INPUT)
rmaalmeida 2:4b7f5a060c22 14 #define SCL_OUT() pinMode(SCL_PIN,OUTPUT)
rmaalmeida 2:4b7f5a060c22 15 */
rmaalmeida 2:4b7f5a060c22 16
rmaalmeida 2:4b7f5a060c22 17 DigitalInOut SDA(A4);
rmaalmeida 2:4b7f5a060c22 18 DigitalInOut SCL(A5);
rmaalmeida 2:4b7f5a060c22 19
rmaalmeida 2:4b7f5a060c22 20 #define SDA_OFF() (SDA.write(0))
rmaalmeida 2:4b7f5a060c22 21 #define SDA() (SDA.read())
rmaalmeida 2:4b7f5a060c22 22 #define SDA_IN() (SDA.input())
rmaalmeida 2:4b7f5a060c22 23 #define SDA_OUT() (SDA.output())
rmaalmeida 2:4b7f5a060c22 24
rmaalmeida 2:4b7f5a060c22 25 #define SCL_OFF() (SCL.write(0))
rmaalmeida 2:4b7f5a060c22 26 #define SCL() (SCL.read())
rmaalmeida 2:4b7f5a060c22 27 #define SCL_IN() (SCL.input())
rmaalmeida 2:4b7f5a060c22 28 #define SCL_OUT() (SCL.output())
rmaalmeida 2:4b7f5a060c22 29
rmaalmeida 2:4b7f5a060c22 30
rmaalmeida 2:4b7f5a060c22 31
rmaalmeida 2:4b7f5a060c22 32 void i2cInit(void) {
rmaalmeida 2:4b7f5a060c22 33
rmaalmeida 2:4b7f5a060c22 34 SDA_IN();
rmaalmeida 2:4b7f5a060c22 35 SCL_IN();
rmaalmeida 2:4b7f5a060c22 36 }
rmaalmeida 2:4b7f5a060c22 37
rmaalmeida 2:4b7f5a060c22 38 // Hardware-specific support functions that MUST be customized:
rmaalmeida 2:4b7f5a060c22 39 #define I2CSPEED 10
rmaalmeida 2:4b7f5a060c22 40 void I2C_delay(void) {
rmaalmeida 3:6ca4d7dd8bea 41 /*volatile int v;
rmaalmeida 2:4b7f5a060c22 42 int i;
rmaalmeida 2:4b7f5a060c22 43 for (i = 0; i < I2CSPEED / 2; i++)
rmaalmeida 3:6ca4d7dd8bea 44 v;*/
rmaalmeida 3:6ca4d7dd8bea 45 wait_us(10);
rmaalmeida 2:4b7f5a060c22 46 }
rmaalmeida 2:4b7f5a060c22 47
rmaalmeida 2:4b7f5a060c22 48 unsigned char read_SCL(void) // Set SCL as input and return current level of line, 0 or 1
rmaalmeida 2:4b7f5a060c22 49 {
rmaalmeida 2:4b7f5a060c22 50 SCL_IN();
rmaalmeida 2:4b7f5a060c22 51 return !!SCL();
rmaalmeida 2:4b7f5a060c22 52 }
rmaalmeida 2:4b7f5a060c22 53 unsigned char read_SDA(void) // Set SDA as input and return current level of line, 0 or 1
rmaalmeida 2:4b7f5a060c22 54 {
rmaalmeida 2:4b7f5a060c22 55 SDA_IN();
rmaalmeida 2:4b7f5a060c22 56 return !!SDA();
rmaalmeida 2:4b7f5a060c22 57
rmaalmeida 2:4b7f5a060c22 58 }
rmaalmeida 2:4b7f5a060c22 59 void clear_SCL(void) // Actively drive SCL signal low
rmaalmeida 2:4b7f5a060c22 60 {
rmaalmeida 2:4b7f5a060c22 61 SCL_OUT();
rmaalmeida 2:4b7f5a060c22 62 SCL_OFF();
rmaalmeida 2:4b7f5a060c22 63 }
rmaalmeida 2:4b7f5a060c22 64
rmaalmeida 2:4b7f5a060c22 65 void clear_SDA(void) // Actively drive SDA signal low
rmaalmeida 2:4b7f5a060c22 66 {
rmaalmeida 2:4b7f5a060c22 67 SDA_OUT();
rmaalmeida 2:4b7f5a060c22 68 SDA_OFF();
rmaalmeida 2:4b7f5a060c22 69 }
rmaalmeida 2:4b7f5a060c22 70
rmaalmeida 2:4b7f5a060c22 71 unsigned char started = 0; // global data
rmaalmeida 2:4b7f5a060c22 72 void i2c_start(void) {
rmaalmeida 2:4b7f5a060c22 73 //se j� estiver iniciado, prepara para reenviar o bit de start
rmaalmeida 2:4b7f5a060c22 74 if (started) {
rmaalmeida 2:4b7f5a060c22 75 read_SDA();
rmaalmeida 2:4b7f5a060c22 76 I2C_delay();
rmaalmeida 2:4b7f5a060c22 77 while (read_SCL() == 0); // Clock stretching
rmaalmeida 2:4b7f5a060c22 78 // Repeated start setup time, minimum 4.7us
rmaalmeida 2:4b7f5a060c22 79 I2C_delay();
rmaalmeida 2:4b7f5a060c22 80 }
rmaalmeida 2:4b7f5a060c22 81 if (read_SDA() == 0) {
rmaalmeida 2:4b7f5a060c22 82 //Houve problema de comunica��o
rmaalmeida 2:4b7f5a060c22 83 }
rmaalmeida 2:4b7f5a060c22 84 // SCL is high, set SDA from 1 to 0.
rmaalmeida 2:4b7f5a060c22 85 clear_SDA();
rmaalmeida 2:4b7f5a060c22 86 I2C_delay();
rmaalmeida 2:4b7f5a060c22 87 clear_SCL();
rmaalmeida 2:4b7f5a060c22 88 started = 1;
rmaalmeida 2:4b7f5a060c22 89 }
rmaalmeida 2:4b7f5a060c22 90
rmaalmeida 2:4b7f5a060c22 91 void i2c_stop(void) {
rmaalmeida 2:4b7f5a060c22 92 // set SDA to 0
rmaalmeida 2:4b7f5a060c22 93 clear_SDA();
rmaalmeida 2:4b7f5a060c22 94 I2C_delay();
rmaalmeida 2:4b7f5a060c22 95 while (read_SCL() == 0); // Clock stretching
rmaalmeida 2:4b7f5a060c22 96 I2C_delay();
rmaalmeida 2:4b7f5a060c22 97 if (read_SDA() == 0) {
rmaalmeida 2:4b7f5a060c22 98 // arbitration_lost();
rmaalmeida 2:4b7f5a060c22 99 }
rmaalmeida 2:4b7f5a060c22 100 I2C_delay();
rmaalmeida 2:4b7f5a060c22 101 started = 0;
rmaalmeida 2:4b7f5a060c22 102 }
rmaalmeida 2:4b7f5a060c22 103
rmaalmeida 2:4b7f5a060c22 104 void i2c_write_bit(unsigned char bit) {
rmaalmeida 2:4b7f5a060c22 105 if (bit) {
rmaalmeida 2:4b7f5a060c22 106 read_SDA();
rmaalmeida 2:4b7f5a060c22 107 } else {
rmaalmeida 2:4b7f5a060c22 108 clear_SDA();
rmaalmeida 2:4b7f5a060c22 109 }
rmaalmeida 2:4b7f5a060c22 110 I2C_delay();
rmaalmeida 2:4b7f5a060c22 111 while (read_SCL() == 0); // Clock stretching
rmaalmeida 2:4b7f5a060c22 112 if (bit && read_SDA() == 0) {
rmaalmeida 2:4b7f5a060c22 113 //Houve problema de comunica��o
rmaalmeida 2:4b7f5a060c22 114 }
rmaalmeida 2:4b7f5a060c22 115 I2C_delay();
rmaalmeida 2:4b7f5a060c22 116 clear_SCL();
rmaalmeida 2:4b7f5a060c22 117 I2C_delay();
rmaalmeida 2:4b7f5a060c22 118 }
rmaalmeida 2:4b7f5a060c22 119
rmaalmeida 2:4b7f5a060c22 120 unsigned char i2c_read_bit(void) {
rmaalmeida 2:4b7f5a060c22 121 unsigned char bit;
rmaalmeida 2:4b7f5a060c22 122 read_SDA();
rmaalmeida 2:4b7f5a060c22 123 I2C_delay();
rmaalmeida 2:4b7f5a060c22 124 while (read_SCL() == 0); // Clock stretching
rmaalmeida 2:4b7f5a060c22 125 bit = read_SDA();
rmaalmeida 2:4b7f5a060c22 126 I2C_delay();
rmaalmeida 2:4b7f5a060c22 127 clear_SCL();
rmaalmeida 2:4b7f5a060c22 128 I2C_delay();
rmaalmeida 2:4b7f5a060c22 129 return bit;
rmaalmeida 2:4b7f5a060c22 130 }
rmaalmeida 2:4b7f5a060c22 131
rmaalmeida 2:4b7f5a060c22 132 // Write a byte to I2C bus. Return 0 if ack by the slave.
rmaalmeida 2:4b7f5a060c22 133 unsigned char i2cWriteByte(unsigned char send_start, unsigned char send_stop, unsigned char byte) {
rmaalmeida 2:4b7f5a060c22 134 unsigned char bit;
rmaalmeida 2:4b7f5a060c22 135 unsigned char nack;
rmaalmeida 2:4b7f5a060c22 136 if (send_start) {
rmaalmeida 2:4b7f5a060c22 137 i2c_start();
rmaalmeida 2:4b7f5a060c22 138 }
rmaalmeida 2:4b7f5a060c22 139 for (bit = 0; bit < 8; bit++) {
rmaalmeida 2:4b7f5a060c22 140 i2c_write_bit((byte & 0x80) != 0);
rmaalmeida 2:4b7f5a060c22 141 byte <<= 1;
rmaalmeida 2:4b7f5a060c22 142 }
rmaalmeida 2:4b7f5a060c22 143 nack = i2c_read_bit();
rmaalmeida 2:4b7f5a060c22 144 if (send_stop) {
rmaalmeida 2:4b7f5a060c22 145 i2c_stop();
rmaalmeida 2:4b7f5a060c22 146 }
rmaalmeida 2:4b7f5a060c22 147 return nack;
rmaalmeida 2:4b7f5a060c22 148 }
rmaalmeida 2:4b7f5a060c22 149
rmaalmeida 2:4b7f5a060c22 150 // Read a byte from I2C bus
rmaalmeida 2:4b7f5a060c22 151 unsigned char i2cReadByte(unsigned char nack, unsigned char send_stop) {
rmaalmeida 2:4b7f5a060c22 152 unsigned char byte = 0;
rmaalmeida 2:4b7f5a060c22 153 unsigned bit;
rmaalmeida 2:4b7f5a060c22 154 for (bit = 0; bit < 8; bit++) {
rmaalmeida 2:4b7f5a060c22 155 byte = (byte << 1) | i2c_read_bit();
rmaalmeida 2:4b7f5a060c22 156 }
rmaalmeida 2:4b7f5a060c22 157 i2c_write_bit(nack);
rmaalmeida 2:4b7f5a060c22 158 if (send_stop) {
rmaalmeida 2:4b7f5a060c22 159 i2c_stop();
rmaalmeida 2:4b7f5a060c22 160 }
rmaalmeida 2:4b7f5a060c22 161 return byte;
rmaalmeida 2:4b7f5a060c22 162 }
rmaalmeida 2:4b7f5a060c22 163