Super Stepper modules work by executing commands. These commands are transmitted into the control module from a PC computer, Single Board Computer (SBC) or any microcontroller with an UART. Communications are serial and the protocol is very easy to learn and put into practice.

The Protocol:

A message always starts with a Header Byte (HB). The HB contains the device address on the five most significant bits. The three least significant bits contain the opcode or instruction to be executed.

• The address can be any number from 0 to 31. Devices with that address will receive the following bytes of the message and respond to the instruction. Devices with a different address will ignore the following bytes and wait for the next message to arrive.
• The opcode can be any number from 0 to 7. SS Devices can only react to a maximum of 8 opcodes. If more functionality is needed, an expanded opcode is introduced which will include up to 256 extra opcodes as received in the Operand0 Byte.

After the Header byte is received, the device will expect N amount of operands to be sent. This is achieved thanks to the fact that the decoded opcode specifies how many bytes the device needs to receive, in order to acknowledge the entire command.

If all the bytes for a command are received, the device will acknowledge the message. This acknowledge includes information regarding possible errors such as Overruns, Noise and Frame errors happening during communication, returned data if any and a checksum. At this same time the device will commence command execution.

If a timeout occurs and not all the bytes have been received, the device will send a Non-Acknowledge byte indicating timeout and possible errors such as OverRuns, Noise and Frame Error.

8 bit vs 9 bit communications:

There are two data formats for which the SS devices can receive serial messages. The goal is to allow 8 bit UARTS, to interface to the device. For more information on 8 bit vs 9 bit data format please refer to the Data Formats section.

Avayan Electronics recommends using 8 or 9 bit communications on Uni-Node systems. Multi-Node systems should consider using 9 bit communications for improved reliability.

[Data Format] [Configurations] [Mode Bits] [Handshaking]

[Data Format] [Configurations] [Mode Bits] [Handshaking]

Last Updated on Jan 10, 2008

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