REX controls Raspberry Pi User manual
www.rexcontrols.com/rex
Raspberry Pi driver for the REX Control System
(the RPiDrv module)
User guide
REX Controls s.r.o.
Version 2.50.1
2016-11-07
Plzeň (Pilsen), Czech Republic
Contents
1 The RPiDrv driver and the REX Control System 2
1.1 Introduction ................................... 2
1.2 System requirements .............................. 2
1.3 Installation of the driver on the host computer ............... 3
1.4 Installation of the driver on the target device (Raspberry Pi) ....... 3
2 Including the driver in the project 4
2.1 Adding the RPiDrv driver ........................... 4
2.2 Connecting the inputs and outputs in the control algorithm ........ 5
2.2.1 GPIO pins of the Raspberry Pi .................... 5
2.2.2 The PiFace Digital expansion board ................. 7
2.2.3 The UniPi expansion board ...................... 8
2.2.4 The Intellisys PIO expansion board .................. 9
3 Troubleshooting 13
Bibliography 14
1
Chapter 1
The RPiDrv driver and the REX
Control System
1.1 Introduction
This manual describes the RPiDrv driver for working with GPIO pins of the Raspberry
Pi1minicomputer [1] within the REX Control System. Both input and output modes
are supported. The driver also supports the PiFace Digital 1/2 [2] expansion board. The
driver was developed by the REX Controls company.
1.2 System requirements
The RPiDrv driver can be used on all Raspberry Pi models which does have a network
adapter (LAN / WAN).
In order to use the driver, the host computer (development) and the target computer
(runtime) must have the following software installed:
Host computer
Operating system one of the following: Windows Vista/7/8/10
REX Control System version for Windows operating system
Target device
REX Control System version for Raspberry Pi with the Raspbian distribution of
GNU/Linux
IO driver version for Raspberry Pi
1Raspberry Pi is a registered trademark of the Raspberry Pi Foundation.
2
1.3 Installation of the driver on the host computer
The RPiDrv driver is included in the installation package of the Development tools of the
REX Control System. It is necessary to select the corresponding package in the installer.
The REX Control System typically installs to the
C:\Program Files (x86)\REX Controls\REX <version> folder.
The following files are copied to the installation folder:
Bin\RPiDrv_H.dll – Configuration part of the RPiDrv driver.
Doc\PDF\ENGLISH\RPiDrv_ENG.pdf – This user manual.
1.4 Installation of the driver on the target device (Rasp-
berry Pi)
If there is no RexCore runtime module installed on your Pi, install it first using the Getting
started guide of the REX Control System [3]. The installation includes all necessary
drivers including RPiDrv.
If you want to install RPiDrv separately, it can be done from the command line of
Raspberry Pi using the command
sudo apt-get install rex-rpidrvt
3
Chapter 2
Including the driver in the project
The driver is included in the project as soon as the driver is added to the project main
file and the inputs and outputs are connected in the control algorithms.
2.1 Adding the RPiDrv driver
The project main file with the RPiDrv driver included is shown in Figure 2.1.
There are 2 blocks which must be added to the project to include the driver. First the
MODULE block is attached the the Modules output of the EXEC function block. It must be
renamed to RPiDrv.
The other block of type IODRV is connected to the Drivers output of the main EXEC
block. The name of this block (RPI, see Fig. 2.1), is the prefix of all input and output
signals provided by this driver. It is recommended to name the IODRV block according
to the used platform:
•RPI – Raspberry Pi GPIO, PiFace Digital expansion board
•UNP – UniPi expansion board
•PIO – Intellisys PIO platform
The most important parameters of IODRV block are:
module – name of the module linked to the driver, in this case RPiDrv – the name is
CASE SENSITIVE!
classname – class of the driver – the name is CASE SENSITIVE!
•RPiDrv – Raspberry Pi GPIO, PiFace Digital expansion board
•UnpDrv – UniPi expansion board
•PioDrv – Intellisys PIO platform
cfgname – name of the driver configuration file, but this driver does not use any
4
Figure 2.1: An example of project main file with the RPiDrv driver included
factor – multiple of the EXEC block’s tick parameter defining the driver’s task execu-
tion period
The above mentioned parameters of the IODRV function block are configured in Rex-
Draw program. The configuration dialog is shown also in Fig. 2.1.
2.2 Connecting the inputs and outputs in the control algo-
rithm
The inputs and outputs of the driver must be interconnected with the individual tasks
(.mdl files). The individual tasks (QTASK or TASK blocks) are connected to the QTask,
Level0,. . . , Level3 outputs of the main EXEC block.
2.2.1 GPIO pins of the Raspberry Pi
Necessary IODRV block configuration for Raspberry Pi GPIO:
5
•Block name –RPI
•module –RPiDrv
•classname –RPiDrv
The inputs and outputs of the RPiDrv driver can be accessed as shown in Fig. 2.2.
Figure 2.2: Example of input and output flags of the RPiDrv driver
One block of the From type allowing the user to read one input has the Goto tag
set to RPI__GPIO21U, while the other has this tag set to RPI__GPIO22U. The number in
the flag corresponds with the GPIO pin number and the Uletter activates the pull-up
resistor. The block of Goto type allowing the user to set (write) one output has the Goto
tag) set to RPI__GPIO23, the other output is accessed via the RPI__GPIO24 flag. The
blocks always have the RPI prefix right at the beginning of the tag followed by two _
characters (underscore).
Similarly for other pins we can use e.g. the flags:
•Goto,RPI__GPIO22 – digital output 22
•Goto,RPI__GPIO23H – digital output 23, which is set to logical 1(HIGH, ON)
immediately upon initialization
•Goto,RPI__PWM18 – PWM output on pin 18
6
Figure 2.3: GPIO pins numbering for Raspberry Pi.
•From,RPI__GPIO7U – digital input 7 with internal pull-up resistor
•From,RPI__GPIO8D – digital input 8 with internal pull-down resistor
•From,RPI__GPIO21 – digital input 21 without any internal pull-up/down resistor
In general, the link to a particular GPIO pin consist of the driver name RPI, two under-
scores __, pin mode (GPIO or PWM), pin number and an optional symbol Ufor internal
pull-up or Dfor internal pull-down in inputs and Hor Lfor initial state in outputs. The
pin numbering on Raspberry Pi is shown in Fig. 2.3.
All the input and output flags for the Raspberry Pi GPIO pins are prepared by de-
fault in the folder
C:\Program Files (x86)\REX Controls\REX <version>\Examples\RaspberryPi_examples\
00_IO_Flags.
Visit the http://elinux.org/RPi_Low-level_peripherals webpage for detailed in-
formation about individual GPIO pins.
2.2.2 The PiFace Digital expansion board
Necessary IODRV block configuration for PiFace Digital:
•Block name –RPI
•module –RPiDrv
•classname –RPiDrv
Because the inputs and outputs of the board are strictly separated, the input flags
contain PFI string and the output ones contain PFO string as shown in Fig. 2.5. Simi-
larly to the GPIO pins, the pull-up resistors in inputs can be activated by the optional
7
character U in the signal name. There are no pull-down resistors available on the PiFace
Digital.
All the input and output flags for the PiFace Digital expansion board are prepared
by default in the folder
C:\Program Files (x86)\REX Controls\REX <version>\Examples\PiFaceDigital_examples\
00_IO_Flags.
Figure 2.4: Input and output flags when using PiFace Digital
The numbering of the screw terminals of the PiFace Digital is depicted in Fig. 2.5.
It is also possible to read/write all eight inputs/outputs of PiFace Digital at once.
This is faster than working with the individual signals. In that case the user must use
the INOCT and OUTOCT blocks named RPI__PFI and RPI__PFO respectively.
Multiple PiFace Digital boards
It is assumed by default, that the PiFace Digital board is configured to have the address
0. If it is not the case, the address must be included in the input/output flag. E.g.
RPI__PFO3C2 refers to the 4th output of the PiFace Digital card with address 2.
2.2.3 The UniPi expansion board
Necessary IODRV block configuration for UniPi expansion board:
8
Figure 2.5: PiFace Digital 2 – numbering of the screw terminals
•Block name –UNP
•module –RPiDrv
•classname –UnpDrv
The inputs and outputs of the UniPi expansion board can be accessed as shown in
Fig. 2.6. The link to a particular IO pin consist of driver name UNP, two underscores __,
pin number and an optional. The pin numbering of the UniPi expansion board is shown
in Fig. 2.7. All the input and output flags for the UniPi expansion board are by default
prepared in the folder
C:\Program Files (x86)\REX Controls\REX <version>\Examples\UniPi_examples\
00_IO_Flags.
2.2.4 The Intellisys PIO expansion board
Necessary IODRV block configuration for Intellisys PIO expansion board:
•Block name –PIO
•module –RPiDrv
•classname –PioDrv
The inputs and outputs of the Intellisys PIO expansion board can be accessed as
shown in Fig. 2.8. The link to a particular IO pin consist of driver name PIO, two un-
derscores __, pin number and an optional. The pin numbering of the Intellisys PIO
expansion board is shown in Fig. 2.9. All the input and output flags for the Intellisys
PIO expansion board are by default prepared in the folder
9
Figure 2.6: Input and output flags when using UniPi
C:\Program Files (x86)\REX Controls\REX <version>\Examples\PIO_examples\00_
IO_Flags.
10
Figure 2.7: UniPi – numbering of terminals
Figure 2.8: Input and output flags when using Intellisys PIO
11
Figure 2.9: Intellisys PIO – numbering of terminals
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Chapter 3
Troubleshooting
In the case that the diagnostic tools of the REX Control System (e.g. RexView) report
unexpected or incorrect values of inputs or outputs, it is desirable to test the functionality
outside the REX Control System (command line tools, simple Python script, etc.). Also
double check the configuration – the most common problems include:
Hardware problem – incorrect wiring
GPIO pin access problem – the GPIO pin is used by other device (SPI bus, I2C bus,
serial line) or program
In the case that the given input or output works with other software tools and does not
work in the REX Control System, report the problem to us, please. E-mail is preferred,
description to help us process your request as soon as possible:
•Identification of the REX Control System you are using. Simply export it to a file
using the RexView program (Target →Licensing... →Export).
•Short and accurate description of your problem.
•The configuration files of the REX Control System (.mdl files) reduced to the
simplest case which still demonstrates the problematic behavior.
13
Bibliography
[1] The Raspberry Pi Foundation. Raspberry Pi. http://www.raspberrypi.org, 2013.
[2] University of Manchester. PiFace Digital Interface. http://www.piface.org.uk, 2013.
[3] REX Controls s.r.o.. Getting started with REX on Raspberry Pi, 2013.
Documentation reference number: 7567
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