MMA7455L_I2C_Test - MMA7455L test for I2C interface. 10-bit 8g mode.

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Lluis Nadal / Mbed 2 deprecated MMA7455L_I2C_Test

MMA7455L test for I2C interface. 10-bit 8g mode.

main.cpp@0:17e709908189, 2011-08-21 (annotated)

Committer:: lnadal
Date:: Sun Aug 21 10:44:59 2011 +0000
Revision:: 0:17e709908189

Who changed what in which revision?

User	Revision	Line number	New contents of line
lnadal	0:17e709908189	1	#include "mbed.h"
lnadal	0:17e709908189	2
lnadal	0:17e709908189	3	/*
lnadal	0:17e709908189	4	*************************************************************************************************
lnadal	0:17e709908189	5	MMA7455. Simple test for I2C interface and 10-bit 8g mode . 2g, 4g, 8g, digital triple axis accelerometer
lnadal	0:17e709908189	6	with I2C/SPI interface.
lnadal	0:17e709908189	7
lnadal	0:17e709908189	8	In Level Detection Mode and pulse detection mode, dynamic range is set automatically to 8g.
lnadal	0:17e709908189	9	Read or Write Low Byte first.
lnadal	0:17e709908189	10
lnadal	0:17e709908189	11	Wiring:
lnadal	0:17e709908189	12	pin 2, pin 3, pin 5, IADDR0(pin 4), pin 10 and pin 11 tied to ground.
lnadal	0:17e709908189	13	DVdd(pin 1),AVdd(pin 6) and CS(pin 7) tied to 3.3V.
lnadal	0:17e709908189	14	INT1(p8) to mBed's p15(INT1 is not used in this program). INT2(p9) to mBed's p16.
lnadal	0:17e709908189	15
lnadal	0:17e709908189	16	Author: Lluis Nadal. August 2011.
lnadal	0:17e709908189	17	*************************************************************************************************
lnadal	0:17e709908189	18	*/
lnadal	0:17e709908189	19
lnadal	0:17e709908189	20	I2C i2c(p9, p10); // SDA(p13), SCL(p14). 4.7k pull-up resistors.
lnadal	0:17e709908189	21
lnadal	0:17e709908189	22	//pin 4 (IADDR0) tied to ground.
lnadal	0:17e709908189	23	const int addr_R = 0x3B; // Address to read: 111011
lnadal	0:17e709908189	24	const int addr_W = 0x3A; // Address to write: 111010
lnadal	0:17e709908189	25
lnadal	0:17e709908189	26	Serial pc(USBTX, USBRX);
lnadal	0:17e709908189	27
lnadal	0:17e709908189	28	DigitalOut led1(LED1), led2(LED2), led3(LED3), led4(LED4);
lnadal	0:17e709908189	29	InterruptIn int1(p15); //
lnadal	0:17e709908189	30	InterruptIn int2(p16); //
lnadal	0:17e709908189	31
lnadal	0:17e709908189	32	int offset[3];
lnadal	0:17e709908189	33	int v[6];
lnadal	0:17e709908189	34	int a;
lnadal	0:17e709908189	35	char msb, lsb;
lnadal	0:17e709908189	36
lnadal	0:17e709908189	37
lnadal	0:17e709908189	38
lnadal	0:17e709908189	39
lnadal	0:17e709908189	40	void read_8(int n) { // Read 8-bit register
lnadal	0:17e709908189	41	i2c.start();
lnadal	0:17e709908189	42	v[0]=i2c.write(addr_W);
lnadal	0:17e709908189	43	v[1]=i2c.write(n);
lnadal	0:17e709908189	44	i2c.start();
lnadal	0:17e709908189	45	v[2] = i2c.write(addr_R);
lnadal	0:17e709908189	46	v[3]=i2c.read(0);
lnadal	0:17e709908189	47	i2c.stop();
lnadal	0:17e709908189	48	//ACK = v[0]= v[1]= v[2]= 1; NACK = 0. v[3] = value.
lnadal	0:17e709908189	49	pc.printf(" (v[0],v[1],v[2],v[3]) = (%d, %d, %d, %d)\r\n\r\n", v[0],v[1],v[2],v[3]);
lnadal	0:17e709908189	50	}
lnadal	0:17e709908189	51
lnadal	0:17e709908189	52
lnadal	0:17e709908189	53	void read(int n) { // Read 10-bit registers n and n+1
lnadal	0:17e709908189	54	i2c.start();
lnadal	0:17e709908189	55	i2c.write(addr_W);
lnadal	0:17e709908189	56	i2c.write(n); // Starting register(L)
lnadal	0:17e709908189	57	i2c.start();
lnadal	0:17e709908189	58	i2c.write(addr_R);
lnadal	0:17e709908189	59	lsb = i2c.read(0);
lnadal	0:17e709908189	60	i2c.stop();
lnadal	0:17e709908189	61
lnadal	0:17e709908189	62	i2c.start();
lnadal	0:17e709908189	63	i2c.write(addr_W);
lnadal	0:17e709908189	64	i2c.write(n+1); // Next register(H)
lnadal	0:17e709908189	65	i2c.start();
lnadal	0:17e709908189	66	i2c.write(addr_R);
lnadal	0:17e709908189	67	msb = i2c.read(0);
lnadal	0:17e709908189	68	i2c.stop();
lnadal	0:17e709908189	69	pc.printf(" (msb, lsb): (%d, %d)\r\n", msb, lsb);
lnadal	0:17e709908189	70	pc.printf("\r\n");
lnadal	0:17e709908189	71	a = (int)msb;
lnadal	0:17e709908189	72	a = (a << 8) \| lsb;
lnadal	0:17e709908189	73	if ((msb >> 1) == 1) a = a -1024; // If negative
lnadal	0:17e709908189	74	pc.printf(" a = %d\r\n\r\n", a);
lnadal	0:17e709908189	75	}
lnadal	0:17e709908189	76
lnadal	0:17e709908189	77
lnadal	0:17e709908189	78	void write_8(int reg, int data) { // Write 8-bit data to register
lnadal	0:17e709908189	79	i2c.start();
lnadal	0:17e709908189	80	v[0]=i2c.write(addr_W);
lnadal	0:17e709908189	81	v[1]=i2c.write(reg);
lnadal	0:17e709908189	82	v[2] = i2c.write(data);
lnadal	0:17e709908189	83	i2c.stop();
lnadal	0:17e709908189	84	//ACK = v[0]= v[1]= v[2] = 1; NACK = 0.
lnadal	0:17e709908189	85	// pc.printf(" (v[0],v[1],v[2]) = (%d, %d, %d)\r\n", v[0],v[1],v[2]);
lnadal	0:17e709908189	86	// pc.printf("\r\n");
lnadal	0:17e709908189	87	}
lnadal	0:17e709908189	88
lnadal	0:17e709908189	89	void write_offset(int reg, int data) { // Write 11-bit data to offset registers L and H
lnadal	0:17e709908189	90	char H, L;
lnadal	0:17e709908189	91	i2c.start();
lnadal	0:17e709908189	92	i2c.write(addr_W);
lnadal	0:17e709908189	93	i2c.write(reg); // Starting register(L)
lnadal	0:17e709908189	94	if (data < 0) data = 2048 + data ; // If negative
lnadal	0:17e709908189	95	pc.printf(" data = %d\r\n", data);
lnadal	0:17e709908189	96	H = (char) ((data & 0xFF00) >> 8);
lnadal	0:17e709908189	97	L = (char) (data & 0x00FF);
lnadal	0:17e709908189	98	i2c.write(L);
lnadal	0:17e709908189	99	i2c.stop();
lnadal	0:17e709908189	100	i2c.start();
lnadal	0:17e709908189	101	i2c.write(addr_W);
lnadal	0:17e709908189	102	i2c.write(reg+1); // Next register(H)
lnadal	0:17e709908189	103	i2c.write(H);
lnadal	0:17e709908189	104	i2c.stop();
lnadal	0:17e709908189	105	pc.printf(" (H, L) = (%d, %d )\r\n\r\n", H, L);
lnadal	0:17e709908189	106	}
lnadal	0:17e709908189	107
lnadal	0:17e709908189	108
lnadal	0:17e709908189	109
lnadal	0:17e709908189	110
lnadal	0:17e709908189	111	void clr_int() { // Clear interrupt latch
lnadal	0:17e709908189	112	write_8(0x17, 0x03);
lnadal	0:17e709908189	113	write_8(0x17, 0x00); // Default option
lnadal	0:17e709908189	114	}
lnadal	0:17e709908189	115
lnadal	0:17e709908189	116	void flash() {
lnadal	0:17e709908189	117	led4 = 0;
lnadal	0:17e709908189	118	pc.printf("Pulse detected!\r\n");
lnadal	0:17e709908189	119	led4 = 1;
lnadal	0:17e709908189	120	wait(1);
lnadal	0:17e709908189	121	led4 = 0;
lnadal	0:17e709908189	122	clr_int(); // Clear interrupt latch
lnadal	0:17e709908189	123	}
lnadal	0:17e709908189	124
lnadal	0:17e709908189	125
lnadal	0:17e709908189	126
lnadal	0:17e709908189	127
lnadal	0:17e709908189	128	int main() {
lnadal	0:17e709908189	129
lnadal	0:17e709908189	130	i2c.frequency(100000);
lnadal	0:17e709908189	131
lnadal	0:17e709908189	132	led1 = 0, led2 = 0, led3 = 0, led4 = 0;
lnadal	0:17e709908189	133	wait(2);
lnadal	0:17e709908189	134
lnadal	0:17e709908189	135	// Read some 8-bit registers
lnadal	0:17e709908189	136	pc.printf(" Read some registers: \r\n\r\n");
lnadal	0:17e709908189	137
lnadal	0:17e709908189	138
lnadal	0:17e709908189	139	pc.printf(" WHOAMI register: ");
lnadal	0:17e709908189	140	read_8(0x0F); // WHOAMI
lnadal	0:17e709908189	141
lnadal	0:17e709908189	142	pc.printf(" I2C ADDRESS: ");
lnadal	0:17e709908189	143	read_8(0x0D); // I2C ADDRESS
lnadal	0:17e709908189	144
lnadal	0:17e709908189	145	pc.printf(" MODE CONTROL register: ");
lnadal	0:17e709908189	146	read_8(0x16); // Mode control register
lnadal	0:17e709908189	147
lnadal	0:17e709908189	148
lnadal	0:17e709908189	149	// 0x16: Mode[1:0] Control Register:
lnadal	0:17e709908189	150	// 00: Standby Mode
lnadal	0:17e709908189	151	// 01: Measurement Mode
lnadal	0:17e709908189	152	// 10: Level Detection Mode
lnadal	0:17e709908189	153	// 11: Pulse Detection Mode
lnadal	0:17e709908189	154
lnadal	0:17e709908189	155	// 0x16: GLV[1:0] Control Register:
lnadal	0:17e709908189	156	// 00: 8g
lnadal	0:17e709908189	157	// 10: 4g
lnadal	0:17e709908189	158	// 01: 2g
lnadal	0:17e709908189	159
lnadal	0:17e709908189	160	pc.printf( "Write to MODE CONTROL register 0x16\r\n\r\n");
lnadal	0:17e709908189	161	// Write: DRPD = 1, GLVL = 00(8g), MODE: 01(Measurement).
lnadal	0:17e709908189	162	write_8(0x16, 0x41);
lnadal	0:17e709908189	163	clr_int(); // Clear interrupt latch
lnadal	0:17e709908189	164
lnadal	0:17e709908189	165	pc.printf(" MODE CONTROL register updated: ");
lnadal	0:17e709908189	166	read_8(0x16); // MODE CONTROL register is updated
lnadal	0:17e709908189	167
lnadal	0:17e709908189	168	pc.printf(" Interrupt latch register: ");
lnadal	0:17e709908189	169	read_8(0x17); // Interrupt latch register
lnadal	0:17e709908189	170
lnadal	0:17e709908189	171	pc.printf(" Status: ");
lnadal	0:17e709908189	172	read_8(0x09); // Status
lnadal	0:17e709908189	173
lnadal	0:17e709908189	174	// Clear offset registers: 11-bit
lnadal	0:17e709908189	175	pc.printf(" Clear offset registers\r\n\r\n");
lnadal	0:17e709908189	176	write_offset(0x10, 0); // Offset x
lnadal	0:17e709908189	177	write_offset(0x12, 0); // Offset y
lnadal	0:17e709908189	178	write_offset(0x14, 0); // Offset z
lnadal	0:17e709908189	179	wait(0.1);
lnadal	0:17e709908189	180
lnadal	0:17e709908189	181	// Start autocalibration. Lay device down horizontal and do not move
lnadal	0:17e709908189	182	// Average 4 readings
lnadal	0:17e709908189	183	// Offsets must be multiplied by 2
lnadal	0:17e709908189	184	pc.printf(" Autocalibration: lay device down horizontal and do not move\r\n\r\n");
lnadal	0:17e709908189	185	led1 = 1; // Start autocalibration in 4 seconds
lnadal	0:17e709908189	186	wait(4);
lnadal	0:17e709908189	187	offset[0] = 0, offset[1] = 0, offset[2] = 0;
lnadal	0:17e709908189	188
lnadal	0:17e709908189	189	for (int i = 0; i < 4; i++) {
lnadal	0:17e709908189	190
lnadal	0:17e709908189	191	pc.printf(" x: \r\n");
lnadal	0:17e709908189	192	read(0x00);
lnadal	0:17e709908189	193	offset[0] = offset[0]-a;
lnadal	0:17e709908189	194
lnadal	0:17e709908189	195	pc.printf( "y: \r\n");
lnadal	0:17e709908189	196	read(0x02);
lnadal	0:17e709908189	197	offset[1] = offset[1]-a ;
lnadal	0:17e709908189	198
lnadal	0:17e709908189	199	pc.printf(" z: \r\n");
lnadal	0:17e709908189	200	read(0x04);
lnadal	0:17e709908189	201	offset[2] = offset[2]-a;
lnadal	0:17e709908189	202	wait(0.2);
lnadal	0:17e709908189	203	}
lnadal	0:17e709908189	204
lnadal	0:17e709908189	205	led2 = 1; // End autocalibration
lnadal	0:17e709908189	206
lnadal	0:17e709908189	207	// Offsets must be multiplied by 2 and divided by 4 to calculate the average
lnadal	0:17e709908189	208	offset[0] = offset[0]/2;
lnadal	0:17e709908189	209	offset[1] = offset[1]/2;
lnadal	0:17e709908189	210	offset[2] = offset[2]/2 + 2*64; //Z axis output for 1g must be 64 in 10-bit mode
lnadal	0:17e709908189	211
lnadal	0:17e709908189	212
lnadal	0:17e709908189	213	// Write offset registers (11-bit). Offset registers are volatile and are cleared on power off.
lnadal	0:17e709908189	214	pc.printf(" Write offset registers\r\n\r\n");
lnadal	0:17e709908189	215	write_offset(0x10, offset[0]); // Offset x
lnadal	0:17e709908189	216	write_offset(0x12, offset[1]); // Offset y
lnadal	0:17e709908189	217	write_offset(0x14, offset[2]); // Offset z
lnadal	0:17e709908189	218	wait(0.1);
lnadal	0:17e709908189	219
lnadal	0:17e709908189	220
lnadal	0:17e709908189	221	// Read x, y, z with offset correction
lnadal	0:17e709908189	222	pc.printf(" Read x, y, z with offset correction\r\n\r\n");
lnadal	0:17e709908189	223	pc.printf(" x corrected: \r\n");
lnadal	0:17e709908189	224	read(0x00);
lnadal	0:17e709908189	225	pc.printf( "y corrected: \r\n");
lnadal	0:17e709908189	226	read(0x02);
lnadal	0:17e709908189	227	pc.printf(" z corrected: \r\n");
lnadal	0:17e709908189	228	read(0x04);
lnadal	0:17e709908189	229	wait(0.1);
lnadal	0:17e709908189	230
lnadal	0:17e709908189	231	// Single pulse detection
lnadal	0:17e709908189	232	write_8(0x16, 0x43); // DRPD = 1; GLV = 00(8g), MODE: 11(pulse detection).
lnadal	0:17e709908189	233	write_8(0x19, 0x00);
lnadal	0:17e709908189	234	write_8(0x18, 0x00); // Int2 for pulse detection
lnadal	0:17e709908189	235	write_8(0x1B, 0x20); // Unsigned 7-bit Pulse Treshold set to 2g.
lnadal	0:17e709908189	236	write_8(0x1C, 0x10); // Pulse duration set to 8 ms
lnadal	0:17e709908189	237	int2.rise(&flash); // Attach flash function to int2
lnadal	0:17e709908189	238	pc.printf(" Start pulse detection\r\n\r\n");
lnadal	0:17e709908189	239	led3 = 1; // Start pulse detection
lnadal	0:17e709908189	240
lnadal	0:17e709908189	241	while (1) {
lnadal	0:17e709908189	242	}
lnadal	0:17e709908189	243	}

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Type:	Program
Mbed OS support:	Mbed 2 deprecated
Created:	21 Aug 2011
Imports:	75
Forks:	0
Commits:	1
Dependents:	0
Dependencies:	1
Followers:	6

main.cpp@0:17e709908189, 2011-08-21 (annotated)

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