Measurement Computing DAQFlex - Manual (Page 4)

4
Chapter 1
Message-based Firmware Specification
The message-based firmware architecture uses a String Message Based Interface (SMBI) to
communicate with supported devices using a minimal number of device transactions.
For those interested in developing a driver to interface directly with the device, the source code for the
DAQFlex software API may be used as a guide.
Click on a link below for more information about the firmware specification:
 SMBI data types
 Communication mechanism
 Message-based control transfers
 Analog input data format
 Programming and developing applications
 Updating device firmware
 Updating the FPGA configuration bitfile on a non-Windows system
 Calibrating a device
 Hardware reference
Note that not all of the messages supported by the software are supported when talking directly to the
device firmware.
SMBI data types
Special formatting characters are returned with RAW data (except streaming data from bulk transfers)
to indicate the following data types:
 char[64]: String data in a character array
 uint8: unsigned 8-bit value
 uint16: unsigned 16-bit value
 uint32: unsigned 32-bit value
 float32: float 32-bit value
Communication mechanism
The device enumerates as a USB device using an MCC driver.
Control transfers
 Control transfers to endpoint 0 are used to communicate with the device.
 The control transfer maximum buffer size is 64 bytes.
 The control transfers are vendor transfers.
 The command code is in the bRequest field.
o SMBI uses the 0x80 data type for strings, and the 0x81 data type for RAW data, when
supported.
 Parameters passed for OUT control transfers are sent during the data stage.
 The SMBI data stage returns RAW data, with LSB first.