Purpose of this article is to inform readers about implementation USB interface into singlechip microcontroller, which this interface directly not supports. Simply: implementation USB interface on firmware level (similar as emulation of RS232 interface in microcontrollers, which not have RS232 support). This project includes development of firmware on microcontroller side, driver development on computer side (for Windows operating system) , development of DLL library for functions calling from another programs (programmers level) and development of demo program (users level), which shows all functions of this device. Device is named IgorPlug-USB (AVR) (as successor of my previous device for computer remote control IgorPlug - serial port version).
At present time is USB interface very popular especially
within end user. This is due to the simplicity to the end users (Plug and Play,
without restart). For developers is implementation of USB into their
devices more complicated (with comparison to RS232 is USB more complex
protocol). In addition there is need of software support on PC side - device
drivers. Therefore more devices from small vendors are inclined to RS232
communication. This interface is probably the oldest in PC history and has good
operating system support. But in latter years is RS232 removing from standard
included PC interfaces (new computers hasn't RS232). In this case help only
add-on PCI card with this interface.
Implementation of USB into external devices is at present
time solved in two choices:
a) First is using microcontroller,
which have hardware implemented USB interface. Then is necessary to
know how USB works and according this write firmware into microcontroller. And
in addition is necessary to create driver on the computer side (while operating
system not includes it - e.g. standard USB classes). Disadvantage (and this is
the main disadvantage for small vendors and amateurs) is not good availability
of this microcontrollers (PIC, Cypress, Atmel, Intel, ...) and their high price
(with comparison to simple "RS232" microcontrollers).
b) Second option is to use some
universal converter between USB and "another" interface.
This "another" interface depends on type of convertor: there are used
especially RS232, 8-bit data bus, I2C bus. In this case is not need of special
firmware (actually we needn't to know how USB works) and no need of driver
writing (vendor of converter offer free drivers). Disadvantage is higher price
of the complete device and greater dimensions of product (need of one chip
more).
My solution,
which I have resolved to develop - and successfully finished ;-) - is
USB implementation into cheap microcontroller through the emulation of USB
protocol in firmware of microcontroller. Problem during design
was microcontroller speed. Speed of USB bus is too high: LowSpeed - 1.5Mbit/s,
FullSpeed - 12Mbit/s, HighSpeed - 480Mbit/s. Normal microcontrollers are maximum
performance cca: AT89C2051 - 2MIPS = 24MHz/(12cycl/inst.), PIC16F84 - 5MIPS =
20MHz/(4cycl/inst.), AT90S23x3 - 10MIPS = 10MHz/(1cycl/inst.). There exist
microcontrollers with highest speeds too, but they are poorly available (price
too) and are biggest (more pins - difficult construction). For all that I have
decided for microcontrollers PIC16F84 or AT90S1200/AT90S23x3, which would be
"enough" for LowSpeed USB. For highest USB speeds is this solution not
good - for one bit from USB processing is need of several cycles of
microprocessor: reading, comparison, storing, some operation, ... .
Firstly I choose PIC16F84-20, with which I have
experiences. To ensure synchronizing with USB clock and speed increasing was
used microcontroller clock 24MHz = 6MIPS (PIC was slightly overclocked). For one
bit from USB processing were 4 instructions (4=6MIPS/1.5Mbit for LowSpeed USB).
I reject this solution (after some time) - PIC is too slow (and in addition the
no so good instruction set ...) .
Second try was AT90S1200-12, which satisfied me with
its speed - possible to receive and transmit signal on LowSpeed USB speed. But I
reject this solution too - absence of enough program and data memory - simply
small memory to implement this.
Third try was successful: AT90S2313-10 (or AT90S2323-10,
AT90S2343-10). This are RISC microcontrollers from Atmel
production - AVR family. With comparison with PIC are slow crystal clock, but
have 1 instruction per crystal clock (PIC16F84 has to 1 instruction per 4
crystal clock). In addition their instruction set and architecture is nearly to
RISC. Again because of synchronization with USB clock I used overclocking
to12MHz (AT90S23x3-10 are initially to10MHz only). In this manner I obtained
more performance and 12MHz crystals are "easy to obtain" (with
comparison to e.g. 10.5MHz - which is the multiple of LowSpeed USB clock
1.5Mbit/s too).
My solution offer very simple and cheap hardware (cca
3,-US$). All intelligence is in firmware. Construction is designed as infrared
remote control of computer through USB (successor of construction for serial
port ), but this is universal USB interface too.
This device allow:
Thanks to versatility is possible to use microprocessor on place of universal converter e.g. in application where we want to control (read and write) some input-output pins. Possible application are e.g.: to pins we directly connect I2C thermometer, inputs and outputs of security device, or simply only LED diodes or LCD/LED display etc., etc., etc. .
On the next picture is schematic:
with microprocessor AT90S2313-10 (universal interface):
or with microprocessor AT90S2323-10 (only for IR code receiving) - not tested
yet, but designed for this purpose - was tested by users - WORKS GOOD:
and physical construction (IR receiver: computer remote control for
program Girder):
Simplicity of device is truly wondrous. And is accessible for amateurs too - for their devices connection to USB (this always enjoy - I know this according my experience, when Windows first time find this "New hardware found" ;-) ). Firmware - the heart of device - is the same for both microprocessors. In 8-pin version (AT90S2323-10) you can use only infrared code receiving and writing/reading to/from EEPROM. But 8-pin version is by dimension probably the smallest device connected to USB (SMD version).
For success communication between USB device and computer,
there is necessary to give driver for device. This driver is requested by
operating system during first connection IgorPlug-USB (AVR) into USB
connector in computer. In the future maybe this driver will not be necessary :
by change in firmware is possible, that device will be standard USB class (HID
class, Storage Class ,...), - for this classes has operating system build-in
drivers. Advantage of own driver is, that we have control of driver behavior. I
choose for "own" driver only because of learning "how this
works" and mainly for simplicity of implementation into firmware of device.
Next pictures shows device
installation steps (and driver installation) on the first plugging IgorPlug-USB
(AVR) into USB connector. Driver is the same for Windows98, WindowsME,
Windows2000 and WindowsXP (under Windows95 not works):
Firstly under WindowsXP:
Windows find device IgorPlug-USB (AVR).
Choose install from our location.
Here we browse to folder with installation files (INF file and SYS driver)
Windows
do some necessary changes.
Driver have not digital signature from Microsoft - but we not stop installation.
Windows make backup (for safe recovery ;-) ).
And in case when Windows don't to find SYS driver, ... 
... then we give to him correct path to driver. 
And installation is finished:
And under Windows98:
The same as under WindowsXP, only in another visual form.
After success installation we
can look at device in "Device manager":
Device Manager under WindowsXP:
Device Manager under Windows98:
As I mentioned - for correct device operation is necessary
driver, which is requested by operating system during installation. This driver
I not wrote alone - I used one freeware USB driver and for this driver I adapted
firmware. Thanks to versatility of this driver this solution is conform to me. I
only slightly modify this driver I wrote in Microsoft Windows2000 DDK
enviroment (and has some improvements - comparison with old driver). Name of this driver is "IgorPlug.sys"
and is included in installation pack.
For installation is necessary installation
descriptive file INF. Just this file was requested by Windows during
installation of device and we must browse to folder with this INF file if we are
asked for driver location. In this file is install information for given device
- and according to this information will be installed driver and eventually will
be made other actions. I was created this INF file according to template file
from my USB book. Because every USB device must have assigned vendor number (VID)
from USB-organization (USB-IF), then I "borrow" this
number from company Atmel (I hope that Atmel excuse me this borrowing - I
won't to pay cca 1500 US$ for number assignment) and I implement it into
microprocessor and into INF file. Name of this file is "IgorPlug.inf"
and is included in installation pack. So for device installation are
necessary only two files ("IgorPlug.sys" a "IgorPlug.inf").
By this way we had successfully installed device IgorPlug-USB
(AVR). And we can go to test it. For this purpose I had written DLL
library "IgorUSB.dll", which contains functions, which
device IgorPlug-USB (AVR) makes. This DLL library communicates with driver
"IgorPlug.sys" and provide serialization of communication
(when we are using DLL from more threads or applications). Library DLL is
primary dedicated for programmers of end user applications for access to device:
exported functions from DLL are published.
Next pictures shows information about DLL library and SYS
driver as was displayed under WindowsXP:
Finally I had created end user
application - exemplar program "AVR
to USB tester", which shows all functions of device IgorPlug-USB (AVR).
It call functions from DLL library "IgorUSB.dll" and is in fact the
sample program.
Program functions:
Next picture shows functions of demonstrational program AVR to USB tester and its properties (in WindowsXP style):
For programming AVR microcontroller is necessary
programmer. But commercial programmer is for most users hard to obtain
because its high price. Therefore I design simple LPT
programmer of this microlontrollers
- simple connection to computer LPT port. For this programmer I wrote control
software - inside it is also firmware of device IgorPlug-USB (AVR)
(only start program and burn microcontroller) and also schematics of
programmer (for both microcontrollers: AT90S2313 and AT90S2323).
Here is schematic of programmer and its control program (works under WinXP too):
You can download control software in download section.
Development of this device was cca 4 months long (every
evening after work cca 4 hours - long evenings ;-) ) + previous study and
knowledge about USB and AVR microprocessors. Therefore this was not too easy (I
must all study, watch, try alone). But now is no problem for me to change some
function of microcontroller (e.g. omit "infra-buffer" and
instead it to implement RS232 buffer). And USB is now nothing
"unknown" for me (from the physical level to end user application).
Idea of this project was in my head cca 2 years (after my first download of USB
specification) - reborn was after similar project of one Russian
"developer", which make this - but this was only his All Fools Day
joke (but at that time I give the lie to his device). But his project was
impulse for me to my project activity and to slogan : nothing is impossible ;-)
.
The biggest "unknown" was understand
all USB specification (but really all - from the physical level to
end user level). Therefore study of USB was very important. The main information
source was USB specification (free download from http://www.usb.org)
and lately book "USB Měření, řízení a regulace pomocí sběrnice
USB" from publisher BEN . And of course
various internet sources.
During development I was using for
testing many "test" a "information utility"
downloaded from internet (USBcheck, DisplayUSB, SnoopyPro, Fiddler, ...).
For firmware development I was using free tool "AVR Studio 4"
(from Atmel-u pages) and programmer "T51prog"
(from Elnec company). For "physical
observation" was used "Scopemeter FLUKE 123" (wonderful
device) from FLUKE . As template design of
USB device was for me USB mouse "Genius NetScroll+" from Genius
company (bought in Agem-e). The microprocessor
(and the "unsuccessful" too) I has bought in GM-electronic
. So Many Thanks to all for help.
I was using for development next programs and many
thanks of their creators:
And who want to see more pictures from my
"development place" , here are: DevelopmentBoard1,
DevelopmentBoard2, DevelopmentBoard3,
DevelopmentBoard4, DevelopmentPlace1.JPG,
DevelopmentPlace1, DevelopmentTools1,
DevelopmentToolsElnecProgrammer,
TargetDeviceAtmelAVR, TargetDeviceToUSBcable,
LiteratureAndInformationSource.
And some information about my device IgorPlug-USB (AVR) as
was dislayed by test utilities: USBDesignByExample,
USBCheckFullTest, USBCheckDeviceDescriptor,
USBCheckConfigurationDescriptor,
USBCheckInterfaceDescriptor,
USBCheckEndpointDescriptor,
USBCheckViewDescriptors, USBCheck,
SnoopyProDeviceDescriptor,
SnoopyProConfigurationDescriptor,
SnoopyProVendorCommand,
......enough (for unfamiliar persons are this not so clearly).
For the persons concerned to build this device as USB
receiver like small USB key 
I prepared documentation: PCB layout, schematic and PCB devices
location. This documentation you can see here as
PDF file.
Firmware into
microprocessor is available in HEX-file
and now also as source code (I publish it
for more users requests - for adding your own functions). And now I publish
documentation of PC software support (that was in the past only in full
version). Of course: commercial use is not free. As freeware I
publish e.g. computer remote control on serial
port , (and all other my projects) and even if I was requesting small
development fee from satisfied users, so from cca 20 000 downloads (about
which I know) will be helpful only one person (4US$ - thank you) (although time
for answering to cca 1500 e-mails is too much). So there is rule - if there is
something free only per voluntary - no wait from anybody.
Because I want that device will be available for
more users, then for download is : IntelHEX
file for AT90S23x3-10, driver , DLL-library
for access to IgorPlug-USB (AVR) and demonstration
program for control of IgorPlug-USB (AVR) (so all :-o ).
In the next I publish source code of
firmware of microcontroller and also documentation
of DLL library (for writing your own applications). Documentation is
for Delphi, C++Builder/Visual C++, Visual Basic. So everybody
can try how the device work.
For fast device construction is available also simple
LPT programmer of given microcontrollers (AT90S2313-10 and
AT90S2323-10). And for less experienced users is small
installation guide (step by step).
There is only one limitation of this "free"
version - DLL library shows information window during the first run (functions
is the same). For your own application will be better to buy registered version
of DLL library. For vendors, which want to sell complete product::
programmed microprocessor + CD with full version of software and
documentation, I offer full versions for distribution (of course with my
copyright). According this way I want to remove problems with payment - end
users will be buying from internet shops of local vendors in your country.
Price for end user will be cca 150,-Sk (Slovakia) or 4,-Euro (Europe) or 4,-US$
(other world). For distributors will be of course discount (after contract with
me).
The persons concerned for
documentation and for
commercial usage of product can contact me by e-mail.
For utilization of
product as computer remote control - is recommended to read article IgorPlug
.
DOWNLOAD:
Here
is the download (ZIP archive): IntelHEX
into AT90S23x3-10, installation files (driver), DLL library (free version),
exemplar application. This files can be changed in the future (according
to requests there will be changing only DLL library, SYS driver remain the
same).
For programming of microcontroller through LPT
port is necessary to download IgorPlugUSBprogrammer.
And developers will be interested
in package: firmware
source code into AT90S23x3 + interface to DLL library IgorUSB.dll (please
don't abuse). DLL function descriptions are for Delphi, C++Builder/Visual C++,
Visual Basic.
For end users is very useful detailed installation
procedure (small install manual - step by step: plug device into USB,
there appear ... , then insert CD ... , etc.)
I am making decision
to publish (concerned person can contact
me - I am making consumer research):
- documentation for DLL library : for programmers to write
own application - IT ALREADY BECAME
- source code for microcontroller : for firmware changes to
your specific functions - IT ALREADY BECAME
- but this all only for non commercial
use!!! - THIS REMAINS VALID
History:
- January 2003 : finishing, documented and publishing of project
- May 2003 : begin of new project: implementation into ATmega8 as RS232+
converter (see my projects)
- July 2003 : finished implementation of improoved RS232+ interface
into ATmega and AT90S2313 (see IgorPlug-USB
(AVR) RS232.htm)
- August 2003 : created my own driver in DDK with some improvements (more
effective transfer, removed problem during computer
hibernation, ...)
- September 2003 : changed interface of DLL library for correct use in v
C++ and Visual Basic (modified documentation of DLL)
- May 2003 - 2004 : new project based on IgorPlug-USB executed:
Application Note for Atmel Company USB
to RS232 converter
In case of problems with downloads - visit my mirror: http://members.chello.cz/cesko, or contact me by e-mail and I will send it to you by e-mail.
Tested on operating systems:
- Windows95 - no function (need to rewrite driver)
- Windows98, Windows XP, Windows 2000 :
fully functional and tested
- Windows ME : should be fully
functional but not tested (you can test it - and
give me answer by e-mail)
Hardware requirements:
- minimal tested configuration : Intel Pentium 120MHz without MMX,
32MB RAM (Windows 98) (my old PC)
Q: After device plugin into USB port is the device not
recognized - recognized only as "Unknown USB device".
A1: Problem of bad device detection is in hardware. In schematic you must add
series resistors into USB data lines - see schematic on my website. You can increase the resistors from 68R up to 330R.
And additionally you can connect Zener diodes (3.6V) to USB D+ and D- data
lines. Problem appears mainly on notebooks and new computers. Usually is there
no problem when you plug device into external USB hub. Problem is caused by high
voltage coming from microcontroller to USB lines - allowed max. 3.6V (input
current into computer USB port).
A2: If you are using ATtiny2313 you must set fuses during
programming: disable division the external clock by 4 and enable high speed
XTALL.
Note: No driver update helps ;-) .
Q: Is possible to use ATtiny2313 instead AT90S2313?
A: The device is compiled for AT90S2313 but works also on
ATtiny2313 - same HEX file (binary compatible). For correct operation on ATtiny2313 you must set
fuses during programming: disable division the external clock by 4 and enable high speed
XTALL. The HEX file is in download package on my website.
Q: Is possible to program ATtiny2313 with LPT programmer?
A: The programmer is designed for 2313 only. For another AVR use please
another simple programmer - for example from http://www.amwaw.edu.pl/~adybkows/elka/ispprog.html
or http://www.serasidis.gr/circuits/avrprog/avrprog.htm .
The HEX file is in download package on my website.
Q: How to order full version of driver - without the popup
window on startup?
A: Please firstly pay 4,-EURO on www.moneybookers.com
to my account: cesko@internet.sk. Then I will send to you the full version of software
by email. Thanks.
Q: How to port existing firmware (USB for AVR) to another
AVR device?
A: Look here - it is better for porting - written C-language
and more more flexible: http://www.obdev.at/products/avrusb/index.html.
Based on my idea but written from scratch in better way. I suggest this
;-) - perfect work
Q: How to use IgorPlug-USB device in own software?
A: Use "IgorUSB.dll" DLL library from my driver
package. This library contains functions for access this USB device and is
installed into system during device driver installation (no need to distribute
it with your software). Documentation to this functions you can download here.
Device offers received IR signal in oscilloscopic form (times between logic
signal changes). For decoding this oscillograph is up to you (e.g.: my Girder
plugin "IgorPlug.dll" decodes this) - but some know how needed
about IR signal used in remote controls.
Q: Where to obtain source codes of driver?
A: Driver "IgorPlug.sys" has no free sources - as
protection for commercial use. But this driver is very similar to my second
driver for RS232 to USB converter which is free. Source codes of this
driver you can find on page for
IgorPlug-USB to RS232 converter + - in download section here
in this zip file.
Q: How to obtain source codes of firmware which has comments in
English?
A: Source codes are commented in Slovak language (sorry ;-) ). But
there exists also source codes with English comments for similar device: IgorPlug-USB to RS232 converter + -
based on same core.
Q: How fast is the IO access of IgorPlug-USB device?
A: Each USB command takes min. 2ms: this is from USB principle.
USB1.1 has time slot 1ms - so we need 1ms for sending request to device and next
1ms for answer from device (plus additional time for execution on device and PC
software). For example if you are toggling IO pin on device the max. frequency
of LED blinking will be 250Hz (LED is 2ms ON and 2ms OFF => f = 1/(4ms)
= 250 Hz). Therefore - from principle - is USB fast only if large data block
will be transferred in this 1ms slot (but response time is 1ms on USB1.1).
Q: Another problems?
A: Write me email - but I am busy ;-) .
Donation and support !!!:
If you are satisfied with this my smart
idea - you can you can send to me some small financial payment (amount of
payment is your choice):
- here use my e-mail: cesko@internet.sk
as recipient and give me message what you are ordering in
this form. After receiving your order I will inform you and full version of
software I will send to your e-mail (which you write in order form).
WORLDWIDE:
- Lukáš
Dziadkowiec offer on his website well looks USB receiver with all
software for computer remote control. The persons concerned find all
necessary information on his website
(with many photos). Delivery is possible worldwide
by post - very reliable vendor.
SLOVAKIA:
- (in preparation is Pavol Bielopotocký)
- Vrták František offer on website http://vrtak.webpark.sk USB receiver without cover (good solution to 3.5/5.25´ slot in computer) or also in small box in SMD version. Delivery by post. Info, photos and prices is on this site.
- Branislav Rozbora : all information is on http://sektor-x.wz.cz.
CZECH REPUBLIC:
- Lukáš
Dziadkowiec offer on his website well looks USB receiver with all
software for computer remote control. The persons concerned find all
necessary information on his website
(with many photos). Delivery is possible Czech republic
by post.
- Jiři Kalkus : offer USB and serial version. Cable length is optional by customer (0-10 m). Price of USB version is 350,-Kč (1.5m cable). Delivery is possible by post in all Czech Republic or personally in towns Ceske Budejovice and Prague. Contact: tel: +420721758094, e-mail: djbj@volny.cz , ICQ: 230642851, webpage: www.volny.cz/djbj
RUSSIA:
- Evgeniy
Melnikov offer on his website USB receiver. Site: http://evm.wallst.ru
page: http://evm.wallst.ru/main/igorusb/index.htm
Price: receiver (hardware) - 7$, DLL (full version) - 4$. Delivery is fast, cash
on delivery (in Russia), or delivery is
possible in Chelyabinsk (face-to-face).
e-mail: msevm@mail.ru.
SINGAPORE (ASIA PACIFIC REGION):
- Han Loke Su : from Singapore
site offer USB and Serial versions. For DIY, offers SFH5110-38
and AT90S2313-10PI as well. More info on website: http://www.alldiy.info
Delivery is possible within Asia Pacific region
by post.
In case of your interest to sell this
"product" (programmed microprocessor + CD with
documentation and software) I publish your address (or another contact) on
this place. Condition is reliability of your customers. Price of device will be
contracted (cost free for small production volume!!!). You can contact me by e-mail.
www.cesko.host.sk - section Hardware
www.cesko.host.sk/girderplugin.htm -
remote control of computer by infrared remote control
www.appliedp.sk - company for which I am
working and developing something from another brand
www.usb.org - all about USB bus
and another: ...
This site will be continuously renewed with new information (which will be interest).
author: Ing. Igor Češko:
e-mail: cesko@internet.sk
homepage: www.cesko.host.sk
