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AN #178 - Software implementation of USB in AVR Print
This AN from Petr uses the Software USB library from Mr. Ollopa. There is NO support on the USB library. Mr. Ollopa was kind enough to publish the LBX version of his library. While the library works fine, it was not 100% tested and is not supported yet. There will be a commercial version with LIB source which is supported. Please do not ask for details : we do not have them, as soon as there is something news, we will add it.

This software USB library and sample code can add USB device capabilities to most AVR chips.
MCS Electronics also has an add on for the USB AVR chips like USB162, USB1287, etc. This add on is available in the on line shop and has nothing to do with the library used in this AN.

Thanks Petr, for this wonderful AN !
To compile without error, you need to install the library HID_Lib (file "HID_Lib for PureBasic 4.41.exe" in the archive).
For software implementation of the interface USB, use the driver from Mr. Ollopa http://www.mcselec.com/index2.php?option=com_forum&Itemid=59&page=viewtopic&t=7537 USB driver (file "swusb.LBX") .
Copy the lbx file to the LIB folder of BASCOM-AVR.
The example HID joystick was transformed into a demonstration device and USB thermometer.

Demo - device  

Demonstration device allows two-way exchange of arbitrary information with a computer.
The scheme is shown in Figure.

Scheme  

The program has a fairly large size (almost 1000 lines), so will be considered only fragments responsible for the configuration of the USB driver and the exchange of information. In the original program was replaced by the HID device descriptor, such as the joystick, to handle non-standard HID device, which allows exchange of arbitrary information. There was also activated by the second endpoint and is configured to receive information from your computer. This tag defines the type of HID devices. Depends on him, whether the device, keyboard, mouse, joystick, etc. In this demonstration device, HID descriptor has the form  


Data 33 ' Length = 33 bytes
Data &H06 , &H00 , &HFF ' Usage_page(vendor Defined Page 1) 
Data &H09 , &H01 ' Usage(vendor Usage 1)
Data &HA1 , &H02 ' Collection(logical)

Data &H09 , &H01 ' Usage(pointer)
Data &H15 , &H00  ' Logical_minimum(0)
Data &H25 , &HFF  ' Logical_maximum(255)
Data &H75 , &H08 ' Report_size(8)
Data &H95 , &H01  ' Report_count(1)
Data &H81 , &H02 ' Input(data , Var , Abs)

Data &H09 , &H01  ' Usage(pointer)
Data &H15 , &H00  ' Logical_minimum(0)
Data &H26 , &HFF , ' Logical_maximum(255)
Data &H75 , &H08  ' Report_size(8)
Data &H95 , &H01  ' Report_count(1)
Data &H91 , &H02  ' Output(data , Var , Abs)

Data &HC0   ' End_collection

 

In the first line, given a number of bytes in the descriptor.
The second and third line describes the type of device. In our case, this non-standard HID device.
Next is a description of input and output endpoints.

Options Logical_minimum and Logical_maximum determine allowable range of values stored in the buffer of the endpoint.
Parameter Report_count determines the number of bytes transmitted or received for one parcel. The allowable value of 1 ... 8. In a demonstration device, is transmitted and received, only one byte per parcel

The configuration of the endpoints is performed by this code.  

'Address of optional endpoints (Must be > 0. comment-out to not use)
Const _usb_endp2addr = 1
Const _usb_endp3addr = 2
'Valid types are 0 for control or 3 for interrupt
Const _usb_endp2type = 3
Const _usb_endp3type = 3
'Directions are: 0=Out, 1=In. Ignored by control endpoints
Const _usb_endp2direction = 1
Const _usb_endp3direction = 0
'Polling interval (ms) for interrupt endpoints. Ignored by control endpoints
' (Must be at least 10)
Const _usb_endp2interval = 200
Const _usb_endp3interval = 100  

Unique device identifier - Vendor ID and Product ID, set in lines:  

Const _usb_vid = &HAAAA
Const _usb_pid = &HEF22  

Receive and transmit data, are performed in the main loop program.  

Do
 Resetcounter
= 0
 
'Check for reset here
 
While _usb_pin._usb_dminus = 0
 
Incr Resetcounter
 
If Resetcounter = 1000 Then
 
Call Usb_reset()
 
End If
 
Wend

 
'Check for received data
 
If _usb_status._usb_rxc = 1 Then
 
If _usb_status._usb_setup = 1 Then
 
'Process a setup packet/Control message
 
Call Usb_processsetup(_usb_tx_status)
 
Elseif _usb_status._usb_endp1 = 1 Then
 
' Input data endpoints
 
Portb = _usb_rx_buffer(2) ' Copy USB data in Portb
 
End If
 
'Reset the RXC bit and set the RTR bit (ready to receive a new packet)
 _usb_status
._usb_rtr = 1
 _usb_status
._usb_rxc = 0
 
End If  


 Buttons_current
= Pinc
 Buttons_current
= Buttons_current And 3
 
If Buttons_current <> Buttons_last Then
 
'Queue data to be sent on endpoint 2 (HID report)
 
If _usb_tx_status2._usb_txc = 1 Then
 Buttons_last
= Buttons_current
 _usb_tx_buffer2
(2) = Buttons_current
 
Call Usb_send(_usb_tx_status2 , 1) ' Send data in PC
 
End If
 
End If
Loop

End

 

When new data from the computer will flag set _usb_endp1 in variable _usb_status. Incoming data is stored in an array _usb_rx_buffer. In the demonstration program, for one parcel, received only a single byte of data, as described in the HID contango. This byte is copied into Portb microcontroller.  

To transfer data from the microcontroller to the computer, the data stored in an array _usb_tx_buffer2. After this function is called Usb_send. Her second argument - the number of transferred bytes. But before that, check the readiness USB driver to transfer data by checking the flag _usb_txc,  variable _usb_tx_status2.  

To work with the demonstration device was developed by a computer program HID_Example_IO.exe  

USB thermometer  

USB thermometer is based on a package of demonstration device. Major changes were made in the main program loop.  

Config 1wire = Portc.5

Dim 1wire_array(9) As Byte
Dim W_1wire As Word
Dim Dsid1(8) As Byte
Dim Flaginputtermo As Byte

Dim Resetcounter As Word
Dim Idlemode As Byte


Enable Interrupts


 W_1wire
= 1wirecount()
 Dsid1
(1) = 1wsearchfirst()
 
1wreset  ' reset the bus
 
1wwrite &HCC  ' skip rom
 
1wwrite &H44  ' Convert T
 
Timer1=0
 Flaginputtermo
= 0

Do
 Resetcounter
= 0

 
'Check for reset here
 
While _usb_pin._usb_dminus = 0
 
Incr Resetcounter
 
If Resetcounter = 1000 Then
 
Call Usb_reset()
 
End If
 
Wend

 
'Check for received data
 
If _usb_status._usb_rxc = 1 Then
 
If _usb_status._usb_setup = 1 Then
 
'Process a setup packet/Control message
 
Call Usb_processsetup(_usb_tx_status)
 
Elseif _usb_status._usb_endp1 = 1 Then
 
' Input data endpoints
 
End If
 
'Reset the RXC bit and set the RTR bit (ready to receive a new packet)
 _usb_status
._usb_rtr = 1
 _usb_status
._usb_rxc = 0
 
End If



 
If Flaginputtermo = 1 Then
 Flaginputtermo
= 0
 
1wverify Dsid1(1)
 
1wwrite &HBE
 1wire_array
(1) = 1wread(9)
 
1wreset  ' reset the bus
 
1wwrite &HCC  ' skip rom
 
1wwrite &H44  ' Convert T
 
'Queue data to be sent on endpoint 2 (HID report)
 
If _usb_tx_status2._usb_txc = 1 Then
 _usb_tx_buffer2
(2) = 1wire_array(1)
 _usb_tx_buffer2
(3) = 1wire_Array(2)
 
Call Usb_send(_usb_tx_status2 , 2) ' Send data (2 bytes) in PC
 
End If
 
End If



Loop

End  

From the main loop removed code that takes data from the computer and added code, the survey sensor DS18B20. The data from the sensor to read no more than once per 750 milliseconds. In order not to delay the work of the main loop for a relatively long period of time, we used variable Flaginputtermo as flag. In interrupts of the timer Timer1, occurring approximately once per second, the variable is written the number 1, which is a sign of the need to read data from the sensor. Upon completion of reading, the data is copied from the array 1wire_array in array _usb_tx_buffer2 and call the function Usb_send, transmitting data (2 bytes) by bus USB to a computer.  

In the HID report was a small change (highlighted in green color) associated with the need to transfer 2 bytes for sending.  

Data 33 ' Length = 33 bytes
Data &H06 , &H00 , &HFF ' Usage_page(vendor Defined Page 1) 
Data &H09 , &H01 ' Usage(vendor Usage 1)
Data &HA1 , &H02 ' Collection(logical)

Data &H09 , &H01 ' Usage(pointer)
Data &H15 , &H00  ' Logical_minimum(0)
Data &H25 , &HFF  ' Logical_maximum(255)
Data &H75 , &H08 ' Report_size(8)
Data &H95 , &H02  ' Report_count(2)
Data &H81 , &H02 ' Input(data , Var , Abs)

Data &H09 , &H01  ' Usage(pointer)
Data &H15 , &H00  ' Logical_minimum(0)
Data &H26 , &HFF , ' Logical_maximum(255)
Data &H75 , &H08   ' Report_size(8)
Data &H95 , &H01  ' Report_count(1)
Data &H91 , &H02  ' Output(data , Var , Abs)

Data &HC0   ' End_collection  

To display the temperature on the computer screen, the program is USB_thermometer.exe  


 
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