Rodrigo Miguez / Mbed 2 deprecated i2c_acelerometro

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Dependencies:   BLE_API mbed nRF51822 circular_buffer

main.cpp@6:fa74a43cae81, 2016-01-21 (annotated)

Committer:
agufal
Date:
Thu Jan 21 15:37:48 2016 +0000
Revision:
6:fa74a43cae81
Parent:
5:d5dba5370918
Child:
7:e4f89c858e61
a?adidos comentarios

Who changed what in which revision?

UserRevisionLine numberNew contents of line
agufal 6:fa74a43cae81 1 /*
agufal 6:fa74a43cae81 2 * Esto es para la placa Xtrinsic-Sense Board de element14, mas
agufal 6:fa74a43cae81 3 * concretamente para el acelerometro MMA8491Q
agufal 6:fa74a43cae81 4 */
agufal 0:c123bc196680 5 #include "mbed.h"
agufal 0:c123bc196680 6
agufal 0:c123bc196680 7 I2C i2c(p30, p7);
agufal 0:c123bc196680 8 Serial pc(p9, p11);
agufal 0:c123bc196680 9 //LEDS
agufal 0:c123bc196680 10 DigitalOut led2(LED2);
agufal 0:c123bc196680 11 DigitalOut led1(LED1);
agufal 0:c123bc196680 12 DigitalOut led3(LED3);
agufal 0:c123bc196680 13 DigitalOut led4(LED4);
agufal 0:c123bc196680 14
agufal 5:d5dba5370918 15 /*****************************************************************************
agufal 5:d5dba5370918 16 * El acelerometro tiene una maquina de estados basandose en enable
agufal 5:d5dba5370918 17 * Pagina 11
agufal 5:d5dba5370918 18 * http://www.element14.com/community/servlet/JiveServlet/previewBody/54565-102-1-273580/Datasheet_MMA8491Q.pdf
agufal 5:d5dba5370918 19 *****************************************************************************/
agufal 4:a743917cd04c 20 DigitalOut EN(p16);
agufal 4:a743917cd04c 21
agufal 4:a743917cd04c 22 /*
agufal 5:d5dba5370918 23 * Direccion del acelerometro: 0x55 << 1 = 0xAA
agufal 4:a743917cd04c 24 *
agufal 4:a743917cd04c 25 * Segun el datasheet los pasos son:
agufal 4:a743917cd04c 26 * - Mandar un Start Condition, direccion 0x55 y bit de R/W a 0 para indicar escritura. El esclavo manda un ACK
agufal 4:a743917cd04c 27 * - Transmitir la direccion del registro a leer. El esclavo manda un ACK
agufal 4:a743917cd04c 28 * - Transmitir un Repeated Start Condition y luego "direccionar?" al acelerometro con bit de R/W a 1 (lectura del registro)
agufal 4:a743917cd04c 29 * - El esclavo manda un ACK y transmite los datos del registro indicado
agufal 5:d5dba5370918 30 * - Transmitir un NACK y la señal de Stop
agufal 5:d5dba5370918 31 *
agufal 5:d5dba5370918 32 * Los rangos de datos para cada eje son:
agufal 5:d5dba5370918 33 *
agufal 5:d5dba5370918 34 * | Range ±8g
agufal 5:d5dba5370918 35 * 14-bit Data | (1 mg/count)
agufal 5:d5dba5370918 36 * ___________________|_______________
agufal 5:d5dba5370918 37 * 01 1111 1111 1111 | +8.000g
agufal 5:d5dba5370918 38 * 01 1111 1111 1110 | +7.998g
agufal 5:d5dba5370918 39 * ... | ...
agufal 5:d5dba5370918 40 * 00 0000 0000 0000 | 0.000g
agufal 5:d5dba5370918 41 * 11 1111 1111 1111 | -0.001g
agufal 5:d5dba5370918 42 * ... | ...
agufal 5:d5dba5370918 43 * 10 0000 0000 0001 | -7.998g
agufal 5:d5dba5370918 44 * 10 0000 0000 0000 | -8.000g
agufal 4:a743917cd04c 45 */
agufal 0:c123bc196680 46 int main(){
agufal 0:c123bc196680 47
agufal 6:fa74a43cae81 48 /*
agufal 6:fa74a43cae81 49 0x3FFF -0.001g
agufal 6:fa74a43cae81 50 0x2001 -7.998g
agufal 6:fa74a43cae81 51 0x2000 -8.000g
agufal 6:fa74a43cae81 52
agufal 6:fa74a43cae81 53 0x1FFF 8.000g
agufal 6:fa74a43cae81 54 0x1FFE 7.998g
agufal 6:fa74a43cae81 55 0x0000 0.000g
agufal 6:fa74a43cae81 56
agufal 6:fa74a43cae81 57 */
agufal 6:fa74a43cae81 58
agufal 5:d5dba5370918 59 const char ACCEL_ADDRESS = 0xAA;
agufal 4:a743917cd04c 60
agufal 6:fa74a43cae81 61 char data_write[1];
agufal 4:a743917cd04c 62 char data_read[7];
agufal 4:a743917cd04c 63
agufal 4:a743917cd04c 64 data_read[0] = 0;
agufal 4:a743917cd04c 65 data_read[1] = 0;
agufal 4:a743917cd04c 66 data_read[2] = 0;
agufal 4:a743917cd04c 67 data_read[3] = 0;
agufal 4:a743917cd04c 68 data_read[4] = 0;
agufal 4:a743917cd04c 69 data_read[5] = 0;
agufal 6:fa74a43cae81 70 data_read[6] = 0;
agufal 0:c123bc196680 71
agufal 0:c123bc196680 72 led1 = 1;
agufal 0:c123bc196680 73 led2 = 1;
agufal 0:c123bc196680 74 led3 = 1;
agufal 0:c123bc196680 75 led4 = 1;
agufal 0:c123bc196680 76
agufal 4:a743917cd04c 77 i2c.frequency(100000); // Min: 0kHz, Max: 400kHz
agufal 5:d5dba5370918 78
agufal 4:a743917cd04c 79 EN = 0; // SHUTDOWN Mode
agufal 4:a743917cd04c 80 wait(0.1);
Alexisfdi 3:80ceedd5ffac 81
Alexisfdi 3:80ceedd5ffac 82 while(1){
Alexisfdi 3:80ceedd5ffac 83
agufal 4:a743917cd04c 84 pc.printf("-----------------------------------------\n");
agufal 4:a743917cd04c 85
agufal 4:a743917cd04c 86 EN = 1; // ACTIVE Mode -> STANDBY Mode
agufal 4:a743917cd04c 87
agufal 5:d5dba5370918 88 /*****************************************************************************
agufal 5:d5dba5370918 89 * Direccion del registro STATUS
agufal 5:d5dba5370918 90 *
agufal 5:d5dba5370918 91 * El registro status cambia diferentes bits para informar de si hay
agufal 5:d5dba5370918 92 * nuevos datos y estan disponibles (1 - Si, 0 - No):
agufal 5:d5dba5370918 93 *
agufal 5:d5dba5370918 94 * ZYXDR : Hay nuevos datos en alguno de los tres ejes
agufal 5:d5dba5370918 95 * ZDR : Hay datos para el eje Z
agufal 5:d5dba5370918 96 * YDR : Hay datos para el eje Y
agufal 5:d5dba5370918 97 * XDR : Hay datos para el eje X
agufal 5:d5dba5370918 98 *
agufal 5:d5dba5370918 99 * El formato del byte es:
agufal 5:d5dba5370918 100 * 0 0 0 0 ZYXDR ZDR YDR XDR
agufal 5:d5dba5370918 101 *****************************************************************************/
agufal 5:d5dba5370918 102 data_write[0] = 0x00;
Alexisfdi 3:80ceedd5ffac 103
Alexisfdi 3:80ceedd5ffac 104 i2c.start();
Alexisfdi 3:80ceedd5ffac 105
agufal 4:a743917cd04c 106 // Como con write ya mandamos la direccion, hacemos los dos primeros pasos a la vez.
agufal 5:d5dba5370918 107 i2c.write(ACCEL_ADDRESS, data_write, 1, true);
agufal 4:a743917cd04c 108
agufal 5:d5dba5370918 109 i2c.read(ACCEL_ADDRESS, data_read, 7, true);
Alexisfdi 3:80ceedd5ffac 110
agufal 4:a743917cd04c 111 pc.printf("Status: %i\n", data_read[0]);
Alexisfdi 3:80ceedd5ffac 112
Alexisfdi 3:80ceedd5ffac 113 if(data_read[0] == 0)
Alexisfdi 3:80ceedd5ffac 114 led1 = 0;
agufal 4:a743917cd04c 115 else
agufal 4:a743917cd04c 116 led1 = 1;
Alexisfdi 3:80ceedd5ffac 117
agufal 4:a743917cd04c 118 // X
agufal 6:fa74a43cae81 119 int ch0 = (data_read[1] << 6) | data_read[2] >> 2;
Alexisfdi 3:80ceedd5ffac 120
agufal 6:fa74a43cae81 121 pc.printf("X: %x\n", ch0);
agufal 4:a743917cd04c 122
agufal 4:a743917cd04c 123 if (ch0 < 0x00FF)
Alexisfdi 3:80ceedd5ffac 124 led2 = 0;
Alexisfdi 3:80ceedd5ffac 125 else
Alexisfdi 3:80ceedd5ffac 126 led2 = 1;
Alexisfdi 3:80ceedd5ffac 127
agufal 4:a743917cd04c 128 // Y
agufal 6:fa74a43cae81 129 int ch1 = (data_read[3] << 6) | data_read[4] >> 2;
agufal 4:a743917cd04c 130
agufal 6:fa74a43cae81 131 pc.printf("Y: %x\n", ch1);
Alexisfdi 3:80ceedd5ffac 132
agufal 4:a743917cd04c 133 if(ch1 < 0x00FF)
Alexisfdi 3:80ceedd5ffac 134 led3 = 0;
Alexisfdi 3:80ceedd5ffac 135 else
Alexisfdi 3:80ceedd5ffac 136 led3 = 1;
Alexisfdi 3:80ceedd5ffac 137
agufal 4:a743917cd04c 138 // Z
agufal 6:fa74a43cae81 139 int ch2 = (data_read[5] << 6) | data_read[6] >> 2;
Alexisfdi 3:80ceedd5ffac 140
agufal 6:fa74a43cae81 141 pc.printf("Z: %x\n", ch2);
agufal 4:a743917cd04c 142
agufal 4:a743917cd04c 143 if(ch2 < 0x00FF)
Alexisfdi 3:80ceedd5ffac 144 led4 = 0;
Alexisfdi 3:80ceedd5ffac 145 else
Alexisfdi 3:80ceedd5ffac 146 led4 = 1;
Alexisfdi 3:80ceedd5ffac 147
agufal 4:a743917cd04c 148 i2c.read(0); // Enviamos un NACK (Espero)
Alexisfdi 3:80ceedd5ffac 149 i2c.stop();
Alexisfdi 3:80ceedd5ffac 150
agufal 4:a743917cd04c 151 EN = 0; // SHUTDOWN Mode
agufal 4:a743917cd04c 152
agufal 4:a743917cd04c 153 wait(0.1);
agufal 5:d5dba5370918 154
Alexisfdi 3:80ceedd5ffac 155 }
agufal 0:c123bc196680 156 }