This version is outdated by a newer approved version.
This version (12 Apr 2013 15:56) was approved by Lucian Sin.The Previously approved version (31 Jan 2013 08:57) is available.
This version (12 Apr 2013 15:56) was approved by Lucian Sin.The Previously approved version (31 Jan 2013 08:57) is available.This is an old revision of the document!
Table of Contents
ADXL345 Pmod Xilinx FPGA Reference Design
Introduction
The ADXL345 is a small, thin, ultralow power, 3-axis accelerometer with high resolution (13-bit) measurement at up to ±16 g. Digital output data is formatted as 16-bit twos complement and is accessible through either a SPI (3- or 4-wire) or I2C digital interface. The ADXL345 is well suited for mobile device applications. It measures the static acceleration of gravity in tilt-sensing applications, as well as dynamic acceleration resulting from motion or shock. Its high resolution (3.9 mg/LSB) enables measurement of inclination changes less than 1.0°.
HW Platform(s):
System: Microblaze, AXI, UART
Quick Start Guide
The bit file provided in the project *.zip file combines the FPGA bit file and the SDK elf files. It may be used for a quick check on the system. All you need is the hardware and a PC running a UART terminal and the programmer (IMPACT).
Required Hardware
Required Software
- Xilinx ISE 13.2 (Programmer (IMPACT) is sufficient for the demo and is available on Webpack).
- A UART terminal (Tera Term/Hyperterminal), Baud rate 115200 for the Avnet LX-9 Microboard or 9600 for the Digilent Nexys™3 Board.
Running Demo (SDK) Program
If you are not familiar with LX9 and/or Xilix tools, please visit
http://www.xilinx.com/products/boards-and-kits/AES-S6MB-LX9.htm for details.
If you are not familiar with Nexys™3 and/or Xilix tools, please visit
http://www.digilentinc.com/Products/Detail.cfm?NavPath=2,400,897&Prod=NEXYS3 for details.
http://www.xilinx.com/products/boards-and-kits/AES-S6MB-LX9.htm for details.
If you are not familiar with Nexys™3 and/or Xilix tools, please visit
http://www.digilentinc.com/Products/Detail.cfm?NavPath=2,400,897&Prod=NEXYS3 for details.
Extract the project from the archive file (ADXL345_<board_name>.zip) to the location you desire.
Avnet LX9 MicroBoard Setup
To begin, connect the PmodACL to J5 connector of LX9 board (see image below). You can use an extension cable for ease of use. Connect the USB cable from the PC to the USB-UART female connector of the board for the UART terminal. The board will be programmed through its USB male connector.
Digilent Nexys™3 Spartan-6 FPGA Board
To begin, connect the PmodACL to JA connector of NEXYS3 board (see image below). You can use an extension cable for ease of use. Connect the USB cables from the PC to the board, one for programming (Digilent USB device) and one for the UART terminal (FT232R USB UART).
FPGA Configuration
Start IMPACT, and double click “Boundary Scan”. Right click and select Initialize Chain. The program should recognize the Spartan 6 device (see screenshot below). Start a UART terminal (set to appropiate baud rate) and then program the device using the bit file provided in the project *.zip archive, located in the “sw” folder (../adxl345/sw/ADXL345.bit).
If programming was successful, the Main Menu will apear in your UART terminal, as seen in the picture below. There are 7 options. Pressing [e], [d], [a], [s], [r], [t] or [q] key will allow you to select the desired option. After the end of every option, all the possible options (the Menu) will be shown again, allowing the user to make a new choice.
Enable Measurement sets the ADXL345 into measurement mode. Any measurement that takes place from that moment on will be valid data.
Disable Measurement sets the ADXL345 into standby mode. Any measurement that takes place from that moment will not be valid data (usually 0).
Display Acceleration displays acceleration data on all 3 Axes.
Select Measurement Range allows choosing between 4 options: ±2g, ±4g, ±8g and ±16g. Desired measurement range is selected by pressing [1] to [4].
Change Acquisition Rate allows choosing different Acquisition rates for the ADXL345. Desired option is selected by pressing [1] to [9].
Select Tap Interrupts allows enabling or disabling tap interrupts. Desired option is selected by pressing [1] to [4]. If the tap option selected is [1] or [3], after a single tap, D2 (LX9) / LD0 (Nexys3) will be ON. If the tap option selected is [2] or [3], after two consecutive taps, D3 and D2 (LX9) / LD1 and LD0 (Nexys3) will both be on at the same time. If the tap option selected is [4], no LEDs will be ON after a single or double tap.
Stop any ongoing action will stop any display of measurements and afterwards display the Main Menu.
Using the reference design
Functional Description
The reference design is a SPI interface used to communicate with the device. The software programs the ADXL345s internal registers, and afterwards reads desired data from the device and prints it via UART. Three Interrupt signals are used in the design: one coming from the ADXL345, one from the UART and a timer interrupt (used for single and double tap LED signaling).
- Connecting the PmodACL to the boards using an extension cable provides ease of use.
- UART must be set to 115200 Baud Rate for the Avnet LX-9 Microboard or 9600 Baud Rate for the Digilent Nexys™3 Board.
Downloads
More information
- Example questions:
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resources/fpga/xilinx/pmod/adxl345.1365773218.txt.gz · Last modified: 12 Apr 2013 15:26 by Lucian Sin