|Online Development Notebook > Index > Programming Overview > Device Commands > WriteB|
WriteB - Write byte value to port B
This is a function that writes a byte value to port B when the port is set as an output. The possible values range from 0-255 (00h to FFh).
Command Syntax: (USBm.dll)
USBm_WriteB( device, data )
The USBm_WriteB function syntax has these parts:
|device||A zero-based index to address the appropriate USB device.|
|data||Byte to write to Port B.|
Port B does not have to have all 8 bits set to output for this to work. You can have a mix of inputs and outputs on the port and this command will set high or low only those lines that are output.
|Public Declare Function USBm_WriteB _|
Lib "USBm.dll" _
(ByVal device As Byte, _
ByVal data As Byte) _
|USBm_WriteB 7, &H0F|
This code fragment writes the value of &H0F to port B of device 7.
|int USBm_WriteB( unsigned char device, unsigned char data );|
Returns true if successful, false otherwise. The byte value is written to Port A⁄B.
Raw Command Format:
|1||Byte Data - This byte is written to port B, D8 - D15
The most significant bit of the byte value is written to D15
Raw Command Format Details:
Byte 0 contains the command. Byte 1 contains the data to write to port B. Byte 2 through byte 7 are unused.
Raw Command Response Format:
Raw Command Response Format Details:
Byte 0 contains the command. Byte 1 through byte 7 are unused.
Raw Command Example Usage:
Writing a 11h to port B with the command 02-11-00-00-00-00-00-00 will set lines B.4 and B.3 high and will set the remainder of the lines low, assuming that they are configured as outputs.
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
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