UM0240 datasheet(27/39 Pages) STMICROELECTRONICS

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UM0240

Firmware

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10.2

Applications

Beside the DFU, application-specific firmware has been developed to enable the Industrial

Communication Board to control and communicate with different application boards.

10.2.1

Power Line Communication (PLC)

Dedicated firmware is available to use in conjunction with Power Line Communication (PLC)

Boards.

Power Line Communication Boards, based on ST7538 and ST7540 power line transceivers,

allow communication over the main AC voltage plugs at a low baud rate. These products are

designed for Home Automation, Building Automation, Automatic Meter Reading, and Street

Lighting control applications as well as other applications that do not require a broad band

communication link.

The PLC dedicated firmware performs basic functions such as:

●

Program transceiver control parameters: channel frequency, baud rate and so on (for

more options see the transceiver datasheet or the dedicated firmware application

note).

●

Transmit a user-defined data stream through the AC line either as single or multiple

repetition.

●

Receive data from the AC line either in free-running mode or after synchronization with

a programmable known sequence (frame header).

●

Perform a communication channel reliability test with a Client-Server application that

can calculate the reachability of each node by sending messages and retrieving

answers. This function implements a Forward Error Correction algorithm to detect if the

network under test requires a FEC algorithm or not.

10.2.2

Motor control

Dedicated FW is available to control different Motor Control boards. In operating a stepper

motor system one of the most common requirements is to execute a relative move. The

move is usually specified as a fixed number of basic motor steps in the clockwise or counter-

clockwise direction. It is common practice to execute this move along a trapezoidal shaped

velocity vs. time profile. FW calculate moving profiles to be used as command signals to

move the controlled motor in a defined position. Given the move distance, acceleration,

deceleration, and peak speed requirement, a profile can be determined. The control

structure is designed such that the velocity and acceleration/deceleration rate can be

changed at will, the task of pre-calculating the velocity profile boils down to determining the

position values where operation switches from acceleration to constant speed and then from

constant speed to deceleration. Execution time for these calculations is not critical since

they are done only once per move and are completed before the move begins. The heart of

the stepper motor control mechanism is the 20-kHz interrupt. This interrupt invokes an

Interrupt Service Routine (ISR) which executes repeatedly on a fixed time interval of 50

microseconds called TICK.

The ISR calculates real time values for velocity and position given the commanded

acceleration (or deceleration) and the present values for velocity and position.

A complete description of algorithms and formulas used by the FW is present in AN2044

Operating principles for Practispin Stepper Motor Motion Control.

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