nielvis 2.2.1

Python API for interacting with National Instrument's ELVIS III Devices

How to Program NI ELVIS III with Python

Info	NI ELVIS III Python API. See GitHub for the latest source and detailed step-by-step instructions.
Author	National Instruments

Overview

In this document we will walk you through the setup, transfer of files, and the use of a Python example on the NI ELVIS III. The NI ELVIS III solution for project-based learning can be programmed with python to help students or educators who are familiar with Python syntax to rapidly acquire measurements by using common SSH clients. Attached to this file are a total of 18 examples which illustrate the use of the NI ELVIS III helper library (academicIO.py).

NI-ELVIS-III-Python-Examples supports Python 2.7, 3.4+.

Table of Contents

• Software Setup
  • Configuring the NI ELVIS III Device
  • Installing Prerequisite Software for NI ELVIS III Python
  • Installing NI ELVIS III Python Examples
    • Download ZIP File and Upload to the Device via SFTP
• Running the Example
• Examples Overview
  • Analog
  • Bus
  • Digital
  • Interrupt
• Opening a Session
• Function Select Register
• NI ELVIS III Shipping Personality Reference

↥ back to top

Software Setup

Configuring the NI ELVIS III Device

In this section we will install the NI Measurement Live Support Files and set up the software environment for the NI ELVIS III.

1. Install the NI Measurement Live Support Files.

2. Connect the NI ELVIS III to the Internet by using the Ethernet or Wireless Network so that the Python libraries can be installed from the Internet. We recommend that you use Ethernet Port.

3. Open Internet Explorer and visit the NI ELVIS III Configuration website: <IP Address of the NI ELVIS III>/WIF.html
   Note: The IP Address can be found on the OLED display of the NI ELVIS III. Press BUTTON 0 until the IP address appears. Enter the IP address from the display.
   

4. Enable the Secure Shell Server and click Restart to restart the device.

5. Set up Time Configuration. Configure the Date, Current time, and Time Zone to your current local time.

   Note:

   • Make sure there is a blue mark at the date you selected.
   • You have to set the Time Configuration again after you restart the device.

6. Install NI-VISA through NI MAX custom software installation if you want to run the UART example.

Installing Prerequisite Software for NI ELVIS III Python

In this section we will install the software needed to execute the NI ELVIS III Python examples and the required packages to use the Python FPGA API.

1. Install and open your favorite SSH client. If you do not have one, we recommend that you use PuTTY:

   • Configure PuTTY or another client as follows:
     • Host Name: <IP Address of the NI ELVIS III>
     • Port: 22
     • Connection Type: SSH
   • Once the connection opens, log in as:
     • login as: admin
     • Password: (Just press Enter. There is no password by default.)

2. Install prerequisite software by running the following commands:
   

   Note: Time configuration must be set before running these commands. If you got any error when downloading nifpga, make sure your Time configuration of the NI ELVIS III is set correctly.

   • Python 2.7

     opkg update
     opkg install python
     opkg install python-pip
     pip install nifpga
     pip install pyvisa
     

   • Python 3.4+

     opkg update
     opkg install python3
     opkg install python3 python3-misc
     curl https://bootstrap.pypa.io/get-pip.py -o get-pip.py | python3
     python3 get-pip.py
     python3 -m pip install nifpga
     python3 -m pip install pyvisa
     

Installing NI ELVIS III Python Examples

In this section we will download the NI ELVIS III Python Examples.

Download ZIP File and Upload to the Device via SFTP

1. Open the NI ELVIS III Python Examples on GitHub.

2. Download the NI ELVIS III Python helper library and Python Examples from GitHub and unzip it.

   1. Download the Example.

   2. Unzip the file you just downloaded.

      

3. Transfer the NI ELVIS III Python Examples to your NI ELVIS III device.

   • Option 1: Transfer files through scp.

     scp -r <folder_name> admin@<id_address>:/home/admin/
     

     For example: scp -r NI-ELVIS-III-Python-Examples/ admin@172.22.11.2:/home/admin/

     Note: Password: (Blank. There is no password by default.)

   • Option 2: Transfer files through FileZilla.

     1. Download and install FileZilla. You are free to use any other application you are comfortable with to transfer files.

     2. Configure FileZilla as the following:

        

        • Host: <IP Address of the NI ELVIS III>
        • Username: admin
        • Password: (Blank. There is no password by default.)
        • Port: 22

     3. Upload NI-ELVIS-III-Python-Examples-master/ into the directory /home/admin.

        

↥ back to top

Running the Example

1. In the same directory where you upload your example folder to, enter the following command to go to the NI-ELVIS-III-Python example directory.

   cd NI-ELVIS-III-Python-Examples-master/
   

2. Run the example:

   python examples/<example_category>/<example_filename>.py
   

   For example: python examples/analog/AI_singleChannel.py.

   Note: Make sure your application broad is powered on before running any example.

↥ back to top

Examples Overview

Go to the comments area at the top of each example to see more details. Click the following links to jump into the example page.

Analog

• AI_configurationOptions
• AI_multipleChannels
• AI_singleChannel
• AO_multipleChannels
• AO_singleChannel

  Related Information

  1 Sample, N Samples, and Continuous Modes

Bus

• Encoder
• I2C
• SPI
• UART
  • If a pyvisa error is shown, make sure the NI-VISA is installed on NI ELVIS III.

Digital

• Button
• DIO_multipleChannels
• DIO_singleChannel
• LED
• PWM

Interrupt

• AIIRQ (Analog Interrupt)
• ButtonIRQ (Button Interrupt)
• DIIRQ (Digital Interrupt)
• TimerIRQ (Timer Interrupt)

↥ back to top

Opening a Session

A context manager ('with' statement) is a convenient way to open/close an NI ELVIS III FPGA session.

with academicIO.AnalogInput({'bank': ai_bank,
                             'channel': ai_channel,
                             'range': ai_range,
                             'mode': ai_mode}) as AI_single_channel:

It is always recommended that you use a context manager to open/close an NI ELVIS III FPGA session. The program will automatically initialize the environment of NI ELVIS III FPGA at the beginning and will automatically free its resources after the 'with' statement ends. Opening a session without a context manager could increase the risk of leaking the session.

See compound statements for more details about the context manager.

You can also manually open/close an NI ELVIS III FPGA session by using the following commands:

# open a session
AI_single_channel = academicIO.AnalogInput()

# close a session
AI_single_channel.close()

If you don’t call the close() function after the Python program closes, you may leak the session and cause errors when you run the program again. If you want the FPGA to keep executing the code after the Python program ends, do not call the close() function in the Python program.

↥ back to top

Function Select Register

• DIO: DIO [0:19] on bank A and bank B
• PWM: DIO [0:19] on bank A and bank B
• Encoder: DIO [0:1], DIO [2:3], …, DIO [18:19] on bank A and bank B
• SPI: DIO [5:7] on bank A and bank B
• I2C: DIO [14:15] on bank A and bank B
• UART: DIO [16:17] on bank A and bank B

NI ELVIS III	DIO	PWM	Encoder	SPI	I2C	UART
DIO 0	DIO 0	PWM 0	ENC.A 0
DIO 1	DIO 1	PWM 1	ENC.B 0
DIO 2	DIO 2	PWM 2	ENC.A 1
DIO 3	DIO 3	PWM 3	ENC.B 1
DIO 4	DIO 4	PWM 4	ENC.A 2
DIO 5	DIO 5	PWM 5	ENC.B 2	SPI.CLK
DIO 6	DIO 6	PWM 6	ENC.A 3	SPI.MISO
DIO 7	DIO 7	PWM 7	ENC.B 3	SPI.MOSI
DIO 8	DIO 8	PWM 8	ENC.A 4
DIO 9	DIO 9	PWM 9	ENC.B 4
DIO 10	DIO 10	PWM 10	ENC.A 5
DIO 11	DIO 11	PWM 11	ENC.B 5
DIO 12	DIO 12	PWM 12	ENC.A 6
DIO 13	DIO 13	PWM 13	ENC.B 6
DIO 14	DIO 14	PWM 14	ENC.A 7		I2C.SCL
DIO 15	DIO 15	PWM 15	ENC.B 7		I2C.SDA
DIO 16	DIO 16	PWM 16	ENC.A 8			UART.RX
DIO 17	DIO 17	PWM 17	ENC.B 8			UART.TX
DIO 18	DIO 18	PWM 18	ENC.A 9
DIO 19	DIO 19	PWM 19	ENC.B 9

↥ back to top

NI ELVIS III Shipping Personality Reference

This document contains reference information about the NI ELVIS III shipping personality. The reference includes information about the registers used to control the peripherals of NI ELVIS III.

You can find NI ELVIS III Shipping Personality Reference here.

↥ back to top