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PmodACL™ Reference Manual
Revised April 15, 2016
This manual applies to the PmodACL rev. E
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
Overview
The Digilent PmodACL is a 3-axis digital accelerometer module powered by the Analog Devices® ADXL345.
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.
The PmodACL.
Features include:
PmodACL™ Reference Manual
Copyright Digilent, Inc. All rights reserved.
Other product and company names mentioned may be trademarks of their respective owners.
Page 2 of 3
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
8
INT1
Interrupt 1
9
NC
Not Connected
10
NC
Not Connected
11
GND
Power Supply Ground
12
VCC
Power Supply (3.3V)
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.
Pin
Signal
Description
1, 5
SCL
Serial Clock
2, 6
SDA
Serial Data
3, 7
GND
Power Supply Ground
4, 8
VCC
Positive Power Supply
Table 2. Pmod header J1.
Table 3. Pmod header J2.
PmodACL™ Reference Manual
Copyright Digilent, Inc. All rights reserved.
Other product and company names mentioned may be trademarks of their respective owners.
Page 3 of 3
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.