Adafruit Analog Accelerometer Breakouts Created by Bill Earl Last updated on 2013-10-02 06:15:18 AM EDT
Guide Contents Guide Contents 2 Overview 3 How it Works: 3 MEMS - Micro Electro-Mechanical Systems 3 Ratiometric Output 4 Assembly and Wiring 5 Assembly: 5 Prepare the header strip: 5 Add the breakout board: 5 And Solder! 5 Wiring: 5 Connect the Power: 5 Connect the X, Y and Z Signal Outputs: 6 Using the Voltage Reference: 6 Calibration and Programming 8 Static Calibration: 8 Gravity as a Calibration Reference 8 Calibration Method: 8 Run the Calibration Sketch 10 Calibr
Overview The ADXL335 , ADXL326 and ADXL377 are low-power, 3-axis MEMS accelerometer modules with ratiometric analog voltage outputs. The Adafruit Breakout boards for these modules feature on-board 3.3v voltage regulation which makes them simple to interface with 5v microcontrollers such as the Arduino. The ADXL335 can measure at least +/3G in the X, Y and Z axis.
converted to an output voltage proportional to the acceleration on that axis. Ratiometric Output Ratiometric output means that the output voltage increases linearly with acceleration over the range. For the ADXL335, that is approximately 0v at -3G to 3.3v at +3G. For the ADXL326, that is approximately 0v at -16G to 3.3v at +16G. For the ADXL377, that is approximately 0v at -200G to 3.3v at +200G. For all modules, the output at 0G in each axis, is about 1/2 full-scale, or 1.65v.
Assembly and Wiring Assembly: These boards come with all surface-mount components pre-soldered. The included header strip can be soldered on for convenient use on a breadboard or with 0.1" connectors. However, for applications subject to extreme accelerations, shock or vibration, locking connectors or direct soldering plus strain relief is advised. Prepare the header strip: Cut the strip[ to length if necessary. It will be easier to solder if you insert it into a breadboard - long pins down.
Connect the VIN pin to the 5v pin on the Arduino. (For 3.3v microprocessors, connect the pin marked 3Vo to the 3.3v supply) Connect the X, Y and Z Signal Outputs: Connect X, Y and Z to the analog pins as shown below: Using the Voltage Reference: For the best possible accuracy and precision, you can use the output of the accelerometer boards voltage regulator as the analog reference for the Arduino. Connect the 3Vo pin on the accelerometer board to the AREF pin on the Arduino.
analog reference to EXTERNAL before calling analogRead() (e.g. in your setup() function). Otherwise, you will short the internal reference with the external reference, possibly damaging your Arduino board. © Adafruit Industries http://learn.adafruit.
Calibration and Programming Static Calibration: As with all sensors, there is some variation in output between samples of these accelerometers. For non-critical applications such as game controllers, or simple motion or tilt sensors, these variations are not important. But for applications requiring precise measurements, calibration to a reliable reference is a good idea.
Mo unt the Senso r: First mount the sensor to a small breadboard (http://adafru.it/65) like the one on the left. The back and squared edges of the breadboard make a reasonably accurate set of reference planes to orient the sensor for calibration. Wire the Senso r: Wire the sensor as shown below. This is equivalent to the circuit shown on the previous page, with the addition of a switch. © Adafruit Industries http://learn.adafruit.
Run the Calibration Sketch Load the sketch below onto the Arduino and run it. Open the Serial Monitor. Lay the breadboard with the sensor on a flat surface Press and hold the button until you see "Calibrate" in the serial monitor. This will calibrate the minimum value for the z axis. Stand the breadboard on the front edge and press the button again. to calibrate +y Repeat this for the three other edges to calibrate +x, -y and -x. Turn the breadboard upside down and press the button again to calibrate +z.
const int xInput = A0; const int yInput = A1; const int zInput = A2; const int buttonPin = 2; // Raw Ranges: // initialize to mid-range and allow calibration to // find the minimum and maximum for each axis int xRawMin = 512; int xRawMax = 512; int yRawMin = 512; int yRawMax = 512; int zRawMin = 512; int zRawMax = 512; // Take multiple samples to reduce noise const int sampleSize = 10; void setup() { analogReference(EXTERNAL); Serial.
Serial.print(zRaw); // Convert raw values to 'milli-Gs" long xScaled = map(xRaw, xRawMin, xRawMax, -1000, 1000); long yScaled = map(yRaw, yRawMin, yRawMax, -1000, 1000); long zScaled = map(zRaw, zRawMin, zRawMax, -1000, 1000); // re-scale to fractional Gs float xAccel = xScaled / 1000.0; float yAccel = yScaled / 1000.0; float zAccel = zScaled / 1000.0; Serial.print(" :: "); Serial.print(xAccel); Serial.print("G, "); Serial.print(yAccel); Serial.print("G, "); Serial.print(zAccel); Serial.
if (yRaw > yRawMax) { yRawMax = yRaw; } if (zRaw < zRawMin) { zRawMin = zRaw; } if (zRaw > zRawMax) { zRawMax = zRaw; } } © Adafruit Industries http://learn.adafruit.
Downloads Data Sheets: ADXL335 Documentation Page (http://adafru.it/aRF) ADXL326 Documentation Page (http://adafru.it/aRG) ADXL377 Data Sheet: (http://adafru.it/cLj) Board Files: ADXL335 and ADXL326 Breakout Board Eagle Files (http://adafru.
Small, Low Power, 3-Axis ±200 g Accelerometer ADXL377 Data Sheet FEATURES GENERAL DESCRIPTION 3-axis sensing Small, low profile package 3 mm × 3 mm × 1.45 mm LFCSP Low power: 300 µA (typical) Single-supply operation: 1.8 V to 3.6 V 10,000 g shock survival Excellent temperature stability Bandwidth adjustment with a single capacitor per axis RoHS/WEEE and lead-free compliant The ADXL377 is a small, thin, low power, complete 3-axis accelerometer with signal conditioned voltage outputs.
ADXL377 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Performance ...................................................................................8 Applications ....................................................................................... 1 Applications Information .................................................................9 General Description ...................................................
Data Sheet ADXL377 SPECIFICATIONS TA = 25°C, VS = 3 V, CX = CY = CZ = 0.1 μF, acceleration = 0 g, unless otherwise noted. All minimum and maximum specifications are guaranteed. Typical specifications are not guaranteed. Table 1. Parameter SENSOR INPUT Measurement Range Nonlinearity Cross-Axis Sensitivity1 SENSITIVITY, RATIOMETRIC2 Sensitivity at XOUT, YOUT, and ZOUT Sensitivity Change Due to Temperature3 ZERO g BIAS LEVEL, RATIOMETRIC Zero g Voltage Zero g Offset vs.
ADXL377 Data Sheet ABSOLUTE MAXIMUM RATINGS ESD CAUTION Table 2. Parameter Acceleration (Any Axis) Unpowered Powered VS All Other Pins Output Short-Circuit Duration (Any Pin to Ground) Operating Temperature Range Storage Temperature Range Rating 10,000 g 10,000 g −0.3 V to +3.6 V (GND − 0.3 V) to (VS + 0.3 V) Indefinite −55°C to +125°C −65°C to +150°C Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device.
Data Sheet ADXL377 RES ST ZOUT VS VS NC PIN CONFIGURATION AND FUNCTION DESCRIPTIONS 16 15 14 13 1 ADXL377 2 TOP VIEW (Not to Scale) 12 NC 11 NC 10 NC 9 NC +Z 5 6 7 8 NC +X GND YOUT 4 GND 3 XOUT RES NOTES 1. NC = NO CONNECT. 2. THE EXPOSED PAD IS NOT INTERNALLY CONNECTED, BUT SHOULD BE SOLDERED FOR MECHANICAL INTEGRITY. 10765-002 +Y Figure 2. Pin Configuration Table 3. Pin Function Descriptions Pin No.
ADXL377 Data Sheet TYPICAL PERFORMANCE CHARACTERISTICS N > 250 for all typical performance figures, unless otherwise noted. N is the number of parts tested and used to produce the histograms. 1.525 35 1.520 1.515 25 OUTPUT VOLTAGE (V) 20 15 10 1.510 1.505 1.500 1.495 1.490 5 OUTPUT VOLTAGE (V) 1.480 –60 10765-003 1.5200 1.5175 1.5150 1.5125 1.5100 1.5075 1.5050 1.5025 1.5000 1.4975 1.4950 1.4925 1.4900 1.4875 1.4850 1.4825 1.4800 0 1.
ADXL377 25 250 20 200 15 150 OUTPUT (g) PERCENT OF POPULATION (%) Data Sheet 10 100 50 5 0 150 200 Figure 12. Typical Output Linearity over the Dynamic Range 10 30 SENSITIVITY (mV/g) 25 20 15 10 SENSITIVITY (mV/g) 14 12 10 8 6 4 10765-011 7.00 6.95 6.90 6.85 6.80 6.75 6.70 6.65 6.60 6.55 6.50 6.45 6.40 6.35 6.30 6.25 6.20 6.15 6.10 6.05 2 6.00 1k Figure 13. Typical Frequency Response 16 SENSITIVITY (mV/g) 100 FREQUENCY (Hz) Figure 10.
ADXL377 Data Sheet THEORY OF OPERATION The ADXL377 is a complete 3-axis acceleration measurement system with a typical measurement range of ±200 g. The ADXL377 contains a polysilicon, surface-micromachined sensor and signal conditioning circuitry to implement an open-loop acceleration measurement architecture. The output signals are analog voltages that are proportional to acceleration.
Data Sheet ADXL377 APPLICATIONS INFORMATION POWER SUPPLY DECOUPLING For most applications, a single 0.1 µF capacitor, CDC, placed close to the ADXL377 supply pins adequately decouples the accelerometer from noise on the power supply. However, in applications where noise is present at the 50 kHz internal clock frequency (or any harmonic thereof), additional care in power supply bypassing is required because this noise can cause errors in acceleration measurement.
ADXL377 Data Sheet AXES OF ACCELERATION SENSITIVITY Figure 14 shows the axes of sensitivity for the accelerometer. Figure 15 shows the output response when the accelerometer is oriented parallel to each of these axes. AZ AX 10765-014 AY Figure 14.
Data Sheet ADXL377 LAYOUT AND DESIGN RECOMMENDATIONS Figure 16 shows the recommended soldering profile; Table 6 describes the profile features. Figure 17 shows the recommended PCB layout or solder land drawing. CRITICAL ZONE TL TO TP tP TP TL tL TSMAX TSMIN tS RAMP-DOWN PREHEAT 10765-016 TEMPERATURE RAMP-UP t25°C TIME Figure 16. Recommended Soldering Profile Table 6.
ADXL377 Data Sheet OUTLINE DIMENSIONS PIN 1 INDICATOR 3.10 3.00 SQ 2.90 0.30 0.25 0.18 0.50 BSC 13 PIN 1 INDICATOR 16 1 12 EXPOSED PAD 1.70 1.60 SQ 1.50 9 1.50 1.45 1.40 4 8 0.20 MIN BOTTOM VIEW 0.05 MAX 0.02 NOM COPLANARITY 0.08 0.152 REF SEATING PLANE 5 FOR PROPER CONNECTION OF THE EXPOSED PAD, REFER TO THE PIN CONFIGURATION AND FUNCTION DESCRIPTIONS SECTION OF THIS DATA SHEET. 04-27-2010-A TOP VIEW 0.45 0.40 0.35 Figure 18.