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1300 Henley Court Pullman, WA 99163 509.334.6306 www.digilentinc.com PmodACL™ Reference Manual Revised April 15, 2016 This manual applies to the PmodACL rev. E Overview The Digilent PmodACL is a 3-axis digital accelerometer module powered by the Analog Devices® ADXL345. Features include:         3-axis, ±2/4/8/16g accelerometer User-selectable resolution Activity/inactivity monitoring Single/double-tap and free-fall detection Small PCB size for flexible designs 1.0 in × 0.8 in (2.5 cm × 2.0 cm) 12-pin Pmod port with SPI interface and 2×4-pin I²C interface Follows Digilent Pmod Interface Specification Type 2A Library and example code available in resource center The PmodACL. 1 Functional Description The PmodACL utilizes Analog Devices ADXL345 to provide high resolution acceleration changes including inclination changes of less than 1.0°. With free fall and single/double-tap detection capabilities, the PmodACL can be configured to take measurements on the user's whim. 2 Interfacing with the Pmod The PmodACL communicates with the host board via the SPI protocol or the I²C protocol. SPI communication is enabled when the Chip Select line is driven low; conversely, the I²C protocol is enabled when the Chip Select line is driven to a logic level high voltage. An interrupt can be triggered whenever a measured axis acceleration data is over a user-defined threshold limit. A data stream setting the threshold activity to a value of 250 mg and Interrupt 1 to be triggered whenever the X and Y axis exceeds the threshold level through SPI is provided below in Table 1. DOC#: 502-097 Copyright Digilent, Inc. All rights reserved. Other product and company names mentioned may be trademarks of their respective owners. Page 1 of 3 PmodACL™ Reference Manual Read/~Write 0 Multi-byte 6-bit Threshold Activity Address 0 1 0 0 1 0 8 bits of Threshold Activity data (62.5 mg/LSB scale) 0 0 0 0 1 0 Multi-byte 6-bit Activity/Inactivity Control Address 0 1 0 0 1 1 Activity/Inactivity Control Settings ACT X ACT Y ACT Z INACT ac/dc INACT X INACT Y 1 1 0 0 0 0 Multi-byte 6-bit Interrupt Enable Address 0 1 0 1 1 1 8 bits of Which Interrupt Sources Are Enabled Single Tap Double Tap Activity Inactivity Free Fall Watermark 0 0 1 0 0 0 0 Read/~Write 0 ACT ac/dc 0 Read/~Write 0 Data Ready 0 0 0 1 INACT Z 0 0 Overrun 0 Table 1. Data stream setting the threshold activity through SPI Once an interrupt has been generated, users may read the data registers (0x32 - 0x37) for the 10 bits of two's complement data in the X, Y, and Z axes, respectively. The data in the two registers for each axis is right-justified with sign extensions as the leading 6 bits. Reading the Interrupt source register (0x30) clears the activity interrupt bit D4. Users may also follow the given example code functions and demonstration to start collecting accelerometer data. 2.1 Pin 1 2 3 4 5 6 7 8 9 10 11 12 Pinout Description Table Signal ~CS MOSI MISO SCK GND VCC INT2 INT1 NC NC GND VCC Description Chip Select Master-out-slave-in Master-in-slave-out Serial Clock Power Supply Ground Power Supply (3.3V) Interrupt 2 Interrupt 1 Not Connected Not Connected Power Supply Ground Power Supply (3.3V) Pin 1, 5 2, 6 3, 7 4, 8 Table 2. Pmod header J1. Signal SCL SDA GND VCC Description Serial Clock Serial Data Power Supply Ground Positive Power Supply Table 3. Pmod header J2. Any external power applied to the PmodACL must be within 2.0V and 3.6V; however, it is strongly recommended that the Pmod is operated at 3.3V. Copyright Digilent, Inc. All rights reserved. Other product and company names mentioned may be trademarks of their respective owners. Page 2 of 3 PmodACL™ Reference Manual 3 Physical Dimensions The pins on the pin header are spaced 100 mil apart. The PCB is 1 inch long on the sides parallel to the pins on the pin header and 0.8 inches long on the sides perpendicular to the pin header. Copyright Digilent, Inc. All rights reserved. Other product and company names mentioned may be trademarks of their respective owners. Page 3 of 3