|Online Development Notebook > Index > Programming Overview > Device Commands > StrobeRead2|
StrobeRead2 - Read 8 bits from a port and strobe a control line
VERSION 1.34+ of the firmware, VERSION 42+ of the DLL
StrobeRead with strobe pulse length.
Command Syntax: (USBm.dll)
USBm_StrobeRead2( device, dataarray, port, sel, len )
The USBm_StrobeRead2 function syntax has these parts:
|device||A zero-based index to address the appropriate USB device.|
|dataarray||A byte array where the returned data will be stored. Minimum size of the array must be 1 byte|
|port||The port for the byte read. A value of 00h is port A, a value of 01h is port B.|
|sel||The strobe direction and the strobe line selection.|
|len||The strobe length.|
|del||The delay between multiple bytes. VERSION 1.46+ of the firmware, VERSION 56+ of the DLL|
Same as StrobeRead, but "len" is the strobe length from about 10 microseconds to about 200 microseconds. The value of "del" is the delay between bytes.
|Public Declare Function USBm_StrobeRead2 _|
Lib "USBm.dll" _
(ByVal device As Byte, _
ByRef dataarray As Byte, _
ByVal port As Byte, _
ByVal sel As Byte, _
ByVal len As Byte) _
ByVal del As Byte) _
|Dim dataarray(1) As Byte|
USBm_StrobeRead2 1, dataarray(0), 0, &H0F, 20, 40
The "20" selects a longer strobe pulse, th 40 is a greater delay between bytes.
|int USBm_StrobeRead2( unsigned char device, unsigned char *data, unsigned char port, unsigned char sel, unsigned char len, unsigned char del );|
Raw Command Format:
|2||Port to write data|
|3||Negative⁄Positive strobe selection and strobe line selection|
|4||Strobe pulse length VERSION 1.38+ of the firmware|
Raw Command Format Details:
Byte 0 contains the command. Byte 1 is not used. Byte 2 indicates the port to write the byte. A value of 00h is port A, a value of 01h is port B.
Byte 3 contains the strobe direction and the strobe line selection.
Byte 4 contains a delay to lengthen the strobe. Valid values from 00h - FFh (0 - 255).
Byte 5 through byte 7 are unused.
|Byte Value||Result||Byte Value||Result|
|00h||Affect A.0||08h||Affect B.0|
|01h||Affect A.1||09h||Affect B.1|
|02h||Affect A.2||0Ah||Affect B.2|
|03h||Affect A.3||0Bh||Affect B.3|
|04h||Affect A.4||0Ch||Affect B.4|
|05h||Affect A.5||0Dh||Affect B.5|
|06h||Affect A.6||0Eh||Affect B.6|
|07h||Affect A.7||0Fh||Affect B.7|
With Byte 3 set to the Bit⁄Line Selection values, the strobe is negative-going. By adding 10h to this value, the strobe will be positive-going. For example: 18h would pulse B.0 from low to high, and back low.
Raw Command Response Format:
|1||Byte value read|
Raw Command Response Format Details:
Byte 0 contains the command. Byte 1 contains the value read. Byte 2 through byte 7 are unused.
Raw Command Example Usage:
If a device is connected to the U4xx that will send a byte of data to port A when B.7 is toggled from high to low and back to high, then the following commands would read this device.
First set the B.7 line high with a SetBitCmd command: 07-0F-00-00-00-00-00-00 The line is set high to begin with because the strobe commands do not initialize the state or direction of the line. (B.7 needs to be set as an output.)
Then toggle B.7 low, read from port A, and toggle B.7 high. 0B-00-00-0F-00-00-00-00 The breakdown of the first four bytes of the command is: 0Bh - StrobeWriteCmd, 00h - not used, 00h - port to read (A), 0Fh - line to toggle (-F) and toggle direction (0-).
Changing to a positive strobe would necessitate changing the initial line value, and substituting 1Fh for the fourth byte.
Hardware: U401 USB Interface U421 USB Interface U451 USB Interface
Programming: USBm DLL Programming Download Files
Application Notes: U4x1 Application Notes Misc Applications and Information FAQ
While every effort has been made to make sure that the information posted on this site is correct, the author can not be held liable for any damages whatsoever for losses as a result of the application of this information. Use this information at your own risk.
USBmicro can design your custom and semi-custom USB product. Email about USB design can be directed to " Robert " at usbmicro.com.
Copyright © USBmicro, L.L.C., 2002-2010