imu-daq-eth - This program acquires data from an ADIS16355 IMU …

Users » yahugh » Code » imu-daq-eth

Hugh Shane / Mbed 2 deprecated imu-daq-eth

This program acquires data from an ADIS16355 IMU via the SPI bus and sends the data to a host computer via UDP over Ethernet.

Dependencies: mbed StrippedDownNetServices

imu-spi.cpp@0:79f663186c05, 2012-05-31 (annotated)

Committer:: yahugh
Date:: Thu May 31 18:37:12 2012 +0000
Revision:: 0:79f663186c05

Who changed what in which revision?

User	Revision	Line number	New contents of line
yahugh	0:79f663186c05	1	//
yahugh	0:79f663186c05	2	// imu-spi.cpp
yahugh	0:79f663186c05	3	//
yahugh	0:79f663186c05	4	// copyright 2010 Hugh Shane
yahugh	0:79f663186c05	5	//
yahugh	0:79f663186c05	6	#include "mbed.h"
yahugh	0:79f663186c05	7	#include "imu-spi.h"
yahugh	0:79f663186c05	8
yahugh	0:79f663186c05	9	ImuSpi::ImuSpi(void) :
yahugh	0:79f663186c05	10	spi(p11, p12, p13), // mosi, miso, sclk (Note: mbed uses SSPx for the SPI busses)
yahugh	0:79f663186c05	11	cs(p16), // IMU chip select, active low
yahugh	0:79f663186c05	12	reset(p15), // IMU reset, active low. Also resets the altimeter.
yahugh	0:79f663186c05	13	diag(p17), // diagnostic output
yahugh	0:79f663186c05	14	imuDataReady(p14), // IMU data-ready interrupt input, active falling edge
yahugh	0:79f663186c05	15	onePPS(p19) // GPS 1 PPS interrupt input, active rising edge
yahugh	0:79f663186c05	16	{
yahugh	0:79f663186c05	17	cs = 1; // set to quiescent state
yahugh	0:79f663186c05	18	diag = 0;
yahugh	0:79f663186c05	19	imuDataReady.mode(PullUp); // just to be safe
yahugh	0:79f663186c05	20	sequenceNumber = 0;
yahugh	0:79f663186c05	21	imuReadIndex = 0;
yahugh	0:79f663186c05	22
yahugh	0:79f663186c05	23	// Initialize the IMU command sequence. Note: register 0x00 is a dummy
yahugh	0:79f663186c05	24	// value that triggers the last read in a burst cycle.
yahugh	0:79f663186c05	25	int8_t regVals[] = {0x04,0x06,0x08,0x0A,0x0C,0x0E,0x3C,0x00};
yahugh	0:79f663186c05	26	for (int i = 0; i < bufferSize; i++) imuRegs[i] = regVals[i];
yahugh	0:79f663186c05	27
yahugh	0:79f663186c05	28	// init the pingpong buffer
yahugh	0:79f663186c05	29	pingpong = 0;
yahugh	0:79f663186c05	30
yahugh	0:79f663186c05	31	// init the buffer ready semaphore
yahugh	0:79f663186c05	32	bufferReady = false;
yahugh	0:79f663186c05	33
yahugh	0:79f663186c05	34	// Setup the SPI bus for 16 bit data, high steady state clock,
yahugh	0:79f663186c05	35	// second edge capture, with a 1 MHz clock rate
yahugh	0:79f663186c05	36	spi.format(16,3);
yahugh	0:79f663186c05	37	spi.frequency(1000000);
yahugh	0:79f663186c05	38
yahugh	0:79f663186c05	39	// init the IMU
yahugh	0:79f663186c05	40	InitImu();
yahugh	0:79f663186c05	41	wait_us(100); // allow things to settle before starting interrupts
yahugh	0:79f663186c05	42
yahugh	0:79f663186c05	43	// Connect the IMU data-ready signal to its interrupt handler
yahugh	0:79f663186c05	44	imuDataReady.fall(this, &ImuSpi::IMUDataReadyISR);
yahugh	0:79f663186c05	45
yahugh	0:79f663186c05	46	// Connect the onePPS signal to its interrupt handler
yahugh	0:79f663186c05	47	imuDataReady.rise(this, &ImuSpi::OnePPSISR);
yahugh	0:79f663186c05	48
yahugh	0:79f663186c05	49	}
yahugh	0:79f663186c05	50
yahugh	0:79f663186c05	51
yahugh	0:79f663186c05	52	// initialize the IMU
yahugh	0:79f663186c05	53	void ImuSpi::InitImu(void) {
yahugh	0:79f663186c05	54	// deselect the IMU
yahugh	0:79f663186c05	55	cs = 1;
yahugh	0:79f663186c05	56	reset = 1;
yahugh	0:79f663186c05	57	// perform a hard reset
yahugh	0:79f663186c05	58	reset = 0; wait(.1); reset = 1; wait(.1);
yahugh	0:79f663186c05	59	// send initialization commands
yahugh	0:79f663186c05	60	WriteSynch(0x34, 0x04); // enable active low data ready on DIO1
yahugh	0:79f663186c05	61	WriteSynch(0x39, 0x01); // Set the gyro sensitivity to 75 deg/sec
yahugh	0:79f663186c05	62	WriteSynch(0x38, 0x00); // Set the FIR filter to its widest possible bandwidth
yahugh	0:79f663186c05	63
yahugh	0:79f663186c05	64	}
yahugh	0:79f663186c05	65
yahugh	0:79f663186c05	66	// When the IMU has data ready, trigger a burst read.
yahugh	0:79f663186c05	67	// Launch an interrupt-driven process to read the IMU
yahugh	0:79f663186c05	68	// accelerometer and gyro registers into the pingpong buffer.
yahugh	0:79f663186c05	69	void ImuSpi::IMUDataReadyISR(void) {
yahugh	0:79f663186c05	70	// initialize the IMU data buffer
yahugh	0:79f663186c05	71	wp = GetBufferWritePtr();
yahugh	0:79f663186c05	72	imuCmdIndex = 0;
yahugh	0:79f663186c05	73	imuReadIndex = 0;
yahugh	0:79f663186c05	74
yahugh	0:79f663186c05	75	// reject spurious interrupts
yahugh	0:79f663186c05	76	if (imuDataReady == 0) {
yahugh	0:79f663186c05	77	// set up the first register read operation
yahugh	0:79f663186c05	78	SendReadCmd(imuRegs[imuCmdIndex++]);
yahugh	0:79f663186c05	79	}
yahugh	0:79f663186c05	80
yahugh	0:79f663186c05	81	}
yahugh	0:79f663186c05	82
yahugh	0:79f663186c05	83	// Start an asynchronous (non-blocking) read of the IMU
yahugh	0:79f663186c05	84	// register designated by 'adr'
yahugh	0:79f663186c05	85	void ImuSpi::SendReadCmd(int8_t adr) {
yahugh	0:79f663186c05	86	int16_t cmd = 0x3f00 & (((int16_t)adr) << 8);
yahugh	0:79f663186c05	87	cs = 0;
yahugh	0:79f663186c05	88	LPC_SSP0->DR = cmd;
yahugh	0:79f663186c05	89
yahugh	0:79f663186c05	90	// start the timer that triggers the next command write
yahugh	0:79f663186c05	91	writeTrigger.attach_us(this, &ImuSpi::WriteTriggerTimeoutISR, (16+9));
yahugh	0:79f663186c05	92
yahugh	0:79f663186c05	93	}
yahugh	0:79f663186c05	94
yahugh	0:79f663186c05	95	// handle the write trigger timeout interrupt
yahugh	0:79f663186c05	96	void ImuSpi::WriteTriggerTimeoutISR(void) {
yahugh	0:79f663186c05	97	diag = 1;
yahugh	0:79f663186c05	98	// buffer the contents of the receive data register that was acquired
yahugh	0:79f663186c05	99	// during the prior command write
yahugh	0:79f663186c05	100	*wp++ = (int16_t)(LPC_SSP0->DR);
yahugh	0:79f663186c05	101
yahugh	0:79f663186c05	102	// if we've acquired an entire buffer of data, signal the foreground task
yahugh	0:79f663186c05	103	if (imuReadIndex++ >= dataSize) {
yahugh	0:79f663186c05	104	int16_t* p = GetBufferWritePtr();
yahugh	0:79f663186c05	105	p[0] = sequenceNumber++; // buffer[0] has garbage, replace with the sequence number
yahugh	0:79f663186c05	106	bufferReady = true;
yahugh	0:79f663186c05	107	cs = 1; // deassert the IMU chip select
yahugh	0:79f663186c05	108	} else {
yahugh	0:79f663186c05	109	// we haven't yet read all the IMU registers, trigger the next read
yahugh	0:79f663186c05	110	SendReadCmd(imuRegs[imuCmdIndex++]);
yahugh	0:79f663186c05	111	}
yahugh	0:79f663186c05	112	diag = 0;
yahugh	0:79f663186c05	113	}
yahugh	0:79f663186c05	114
yahugh	0:79f663186c05	115	// The foreground process uses this method to determine if
yahugh	0:79f663186c05	116	// if a burst read of the IMU is complete. If read was
yahugh	0:79f663186c05	117	// completed, the ping-pong buffers are toggled so that the
yahugh	0:79f663186c05	118	// most recent data is made available to the foreground
yahugh	0:79f663186c05	119	// process.
yahugh	0:79f663186c05	120	bool ImuSpi::IsBufferReady(void) {
yahugh	0:79f663186c05	121	bool ret;
yahugh	0:79f663186c05	122
yahugh	0:79f663186c05	123	if (bufferReady == true) {
yahugh	0:79f663186c05	124	__disable_irq(); // ---- critical
yahugh	0:79f663186c05	125	TogglePingpong();
yahugh	0:79f663186c05	126	bufferReady = false;
yahugh	0:79f663186c05	127	__enable_irq(); // ---- \critical
yahugh	0:79f663186c05	128	ret = true;
yahugh	0:79f663186c05	129	} else {
yahugh	0:79f663186c05	130	ret = false;
yahugh	0:79f663186c05	131	}
yahugh	0:79f663186c05	132
yahugh	0:79f663186c05	133	return ret;
yahugh	0:79f663186c05	134	}
yahugh	0:79f663186c05	135
yahugh	0:79f663186c05	136	// perform a synchronous (blocking) read of the IMU
yahugh	0:79f663186c05	137	// register designated by 'adr'
yahugh	0:79f663186c05	138	int16_t ImuSpi::ReadSynch(char adr) {
yahugh	0:79f663186c05	139	int16_t cmd = 0x3f00 & (((int16_t)adr) << 8);
yahugh	0:79f663186c05	140	int16_t response;
yahugh	0:79f663186c05	141	cs = 0;
yahugh	0:79f663186c05	142	// (1) command a read of the desired register while reading back garbage
yahugh	0:79f663186c05	143	spi.write(cmd);
yahugh	0:79f663186c05	144	// (2) command a read of register 0x00 while reading back the desired register
yahugh	0:79f663186c05	145	response = spi.write(0x3f00);
yahugh	0:79f663186c05	146	cs = 1;
yahugh	0:79f663186c05	147	return response;
yahugh	0:79f663186c05	148	}
yahugh	0:79f663186c05	149
yahugh	0:79f663186c05	150	// perform a synchronous (blocking) write of 'data' to the IMU
yahugh	0:79f663186c05	151	// register designated by 'adr'
yahugh	0:79f663186c05	152	void ImuSpi::WriteSynch(char adr, char data) {
yahugh	0:79f663186c05	153	int16_t cmd = 0x8000 \| (((int16_t)adr) << 8) \| data;
yahugh	0:79f663186c05	154	cs = 0;
yahugh	0:79f663186c05	155	spi.write(cmd);
yahugh	0:79f663186c05	156	cs = 1;
yahugh	0:79f663186c05	157	wait_us(9);
yahugh	0:79f663186c05	158	}
yahugh	0:79f663186c05	159
yahugh	0:79f663186c05	160	// When the GPS 1 PPS signal is asserted, clear the sequence number.
yahugh	0:79f663186c05	161	// This is how IMU data is synched with GPS data.
yahugh	0:79f663186c05	162	void ImuSpi::OnePPSISR(void) {
yahugh	0:79f663186c05	163	sequenceNumber = 0;
yahugh	0:79f663186c05	164	}

Repository toolbox

Export to desktop IDE

Build repository

Repository details

Type:	Program
Mbed OS support:	Mbed 2 deprecated
Created:	31 May 2012
Imports:	18
Forks:	0
Commits:	1
Dependents:	0
Dependencies:	2
Followers:	2

imu-spi.cpp@0:79f663186c05, 2012-05-31 (annotated)

Who changed what in which revision?

Repository toolbox

Repository details

Important Information for this Arm website

Access Warning