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 24-pin IC 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 IC protocol. SPI communication is enabled when the Chip Select line is driven low conversely, the IC 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. Copyright Digilent, Inc. All rights reserved. DOC : 502-097 Page 1 of 3 Other product and company names mentioned may be trademarks of their respective owners. PmodACL Reference Manual Read/~Write Multi-byte 6-bit Threshold Activity Address 0 0 1 0 0 1 0 0 8 bits of Threshold Activity data (62.5 mg/LSB scale) 0 0 0 0 0 1 0 0 Read/~Write Multi-byte 6-bit Activity/Inactivity Control Address 0 0 1 0 0 1 1 1 Activity/Inactivity Control Settings ACT ac/dc ACT X ACT Y ACT Z INACT ac/dc INACT X INACT Y INACT Z 0 1 1 0 0 0 0 0 Read/~Write Multi-byte 6-bit Interrupt Enable Address 0 0 1 0 1 1 1 0 8 bits of Which Interrupt Sources Are Enabled Data Ready Single Tap Double Tap Activity Inactivity Free Fall Watermark Overrun 0 0 0 1 0 0 0 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 Pinout Description Table Pin Signal Description 1 ~CS Chip Select 2 MOSI Master-out-slave-in 3 MISO Master-in-slave-out 4 SCK Serial Clock 5 GND Power Supply Ground 6 VCC Power Supply (3.3V) 7 INT2 Interrupt 2 Pin Signal Description 8 INT1 Interrupt 1 1, 5 SCL Serial Clock 9 NC Not Connected 2, 6 SDA Serial Data 10 NC Not Connected 3, 7 GND Power Supply Ground 11 GND Power Supply Ground 4, 8 VCC Positive Power Supply 12 VCC Power Supply (3.3V) Table 3. Pmod header J2. Table 2. Pmod header J1. 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. Page 2 of 3 Other product and company names mentioned may be trademarks of their respective owners.