1300 Henley Court Pullman, WA 99163 509.334.6306 www.digilentinc.com PmodACL2 Reference Manual Revised May 24, 2016 This manual applies to the PmodACL2 rev. A Overview The PmodACL2 is a 3-axis MEMS accelerometer powered by the Analog Devices ADXL362. By communicating with the chip via the SPI protocol, users may receive up to 12 bits of resolution for each axis of acceleration. Additionally, this module offers external trigger sensing through single or double-tap detection as well as power saving features though its inactivity monitoring. Features include: 3-axis MEMS accelerometer Up to 12 bits of resolution per axis User-selectable resolution Activity/inactivity monitoring Low current consumption at <2 A at 100Hz Free-fall detection Small PCB size for flexible designs 1.0 in 0.8 in (2.5 cm 2.0 cm) Follows Digilent Pmod Interface Specification Type 2A Library and example code available in resource center The PmodACL2. 1 Functional Description The PmodACL2 utilizes Analog Devices ADXL362 to provide MEMS acceleration data to the system board. With its deep 512-sample FIFO buffer, users are able to view a long string of events prior to a triggered interrupt or simply be able to have the system board access acceleration data when the user finds it most convenient. 2 Interfacing with the Pmod The PmodACL2 communicates with the host board via the SPI protocol. To read from the on-board data registers, the Chip Select line must first be pulled low and then send a command byte to read from the data registers (0x0B). The desired address byte must be sent next, and then the desired byte is received with the MSB first on the falling Copyright Digilent, Inc. All rights reserved. DOC : 502-255 Page 1 of 3 Other product and company names mentioned may be trademarks of their respective owners. PmodACL2 Reference Manual clock edge. Because the address pointer auto-increments to the next address byte, it is possible to read multiple bytes consecutively by continuing to pulse the Serial Clock line. An example set of commands to read from the y- axis register is given below: Command Read First Y-axis Address 0 0 0 0 1 0 1 1 0 0 0 0 1 0 1 0 LSB Byte of Y-axis Data MSB Byte of Y-axis Data b7 b6 b5 b4 b3 b2 b1 LSB SX SX SX SX MSB b10 b9 b8 Note: Each SX bit is the same value as the most significant bit of the y-axis data. To read from the FIFO buffer, a command byte to write to a data register (0x0A) must first be sent so that we can configure the FIFO Control register (address 0x28) to indicate that we want the FIFO buffer to store data. After the ADXL362 has been configured to use the FIFO buffer, a command byte to read from the FIFO buffer (0x0D) must first be sent, then followed by pairs of data bytes containing which axis is being measured as well as the acceleration data. An example set of commands to read from the FIFO buffer is given below: Command Read FIFO Control Register Address Command FIFO Read 0 0 0 0 1 0 1 0 0 0 1 1 0 0 0 0 0 0 0 0 1 1 0 1 LSB Byte of Axis Data MSB Byte of Axis Data b7 b6 b5 b4 b3 b2 b1 LSB b15 b14 SX SX MSB b10 b9 b8 Note: Each SX bit is the same value as the most significant bit of the y-axis data. b15 and b14 represent which axis the incoming data represents. 2.1 Pinout Description Table Pinout Table of the PmodACL2 Connector J1 Connector J2 Pin Signal Description Pin Signal Description Pin Signal Description 1 ~CS Chip select 7 INT2 Interrupt Two 1 INT1 Interrupt One Master Out Slave Power Supply 2 MOSI 8 INT1 Interrupt One 2 G In Ground Master In Slave 3 MISO 9 NC Not connected Connector J3 Out 4 SCLK Serial clock 10 NC Not connected Pin Signal Description Power supply Power supply 5 GND 11 GND 1 INT2 Interrupt Two ground ground Power supply Power supply Power Supply 6 VCC 12 VCC 2 G (3.3V) (3.3V) Ground Copyright Digilent, Inc. All rights reserved. Page 2 of 3 Other product and company names mentioned may be trademarks of their respective owners.