General Purpose Sequencer

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SSC-32 General Purpose Sequencer.

Author: Mike Dvorsky

Version: 1.00

Date: Jan 15 2008

Table of Contents

• EEW, EER commands - EEPROM Write,

Read

• EEW Format

• EER Format

• Sequence Format

• Header

• Servo/Speed List

• Time/Pulse Width List

• Memory Map - Sequences in External

EEPROM

• Location 0-255: Sequencer Pointer

Table

• Locations 256-32767: Sequence

Data

• General Notes on Programming EEPROM

• Sequence Example

• Sequence Pointer Table

• Sequence Header

• Servo/Speed List

• Time/Pulse Width List

• Sequencer Commands

• Start a player

• Stop a player

• Change the speed of a player

• Change the pause value of a player

• Go to a step in a sequence

• Query a player

• Examples of Sequencer Commands

EEW, EER commands EEPROM Write, Read.�

The EEW and EER commands are used to write and read external EEPROM data. In order for these

commands to be used, an EEPROM chip must be installed in the 8-pin socket on the SSC-32. The chip

used for testing is a Microchip 24LC256-I/P which has 32768 bytes of storage. Other I

C serial

EEPROMs with comparable pinout should work, but have not been tested.

The primary use of external EEPROM is to store sequences for the General Purpose sequencer. The

first 256 bytes of external EEPROM are reserved exclusively for the GP sequencer, but the other bytes

may be used for other purposes.

EEPROM read and write commands are issued with arguments in decimal format, but the response to

an EEPROM read command is in binary format. This is in keeping with the SSC-32 convention of

receiving commands in decimal format and providing responses in binary format.

NOTE: The current firmware version (SSC32-V2.01GP) requires a - character before the address� �

in EEPROM read and write commands. If this character is omitted, the EEPROM access will be

performed on internal EEPROM of the ATMega168 processor. Future firmware versions will not

require the - character for external EEPROM access.� �

NOTE: No external EEPROM read or write accesses should be performed while a sequence is

executing out of external EEPROM.

EEW Instruction Format

EEW -<addr>,<byte>,<byte>,<byte>, ,<byte><cr>�

• <addr> = the starting address of the data to be written, in decimal format

• <byte> = a byte of data to be written to external EEPROM, in decimal format

Summary of content (8 pages)

PAGE 1
SSC-32 General Purpose Sequencer. Author: Mike Dvorsky Version: 1.
PAGE 2
The EEW command writes up to 32 bytes of EEPROM. To write more than 32 bytes, issue multiple commands. The command may take several milliseconds to complete. When performing multiple successive EEW commands, it is recommended that you wait for each command to complete before starting the next command. There are several ways to do this: • Delay 10ms between EEW commands. • Use an EER command to read back the data just written. The EER command will not return until the EEW has finished.
PAGE 3
Locations 256 � 32767: Sequence Data The sequence pointer table entries point to sequence data. Sequences may be stored at any location, but the only way a sequence can be accessed is through the Sequence Pointer Table.
PAGE 4
bytes. There are several things to note about the time/pulse width list: 1. The Step (N-1)�0 move time is duplicated, appearing at the beginning and the end of the list. This makes it easier for the SSC-32 to play sequences in reverse. 2. Move times are in ms, just like move commands. 3. Move times are 2 bytes each, with the high byte appearing first (i.e. big-endian). 4. The move times should be the times for a normal move speed. The speed can be adjusted faster or slower as the sequence is played.
PAGE 5
@11 = 244 The EEW command to write this portion of the Sequence Pointer table is EEW -10, 1, 244 Sequence Header The sequence header is 3 bytes that specify the sequence number (5), number of servos (2), and number of steps (3). The sequence header begins at EEPROM address 500: @500 = 5 @501 = 2 @502 = 3 The EEW command to write the sequence header is EEW -500, 5, 2, 3 Servo/Speed List The servo/speed list has 3 bytes per servo (1 byte servo number, 2 bytes maximum speed).
PAGE 6
@516 = 88 @517 = 3 Step 1, servo 9 = 1000 @518 = 232 @519 = 5 Step 1, servo 10 = 1500 @520 = 220 @521 = 4 Step 1 to step 2 time = 120 @522 = 176 @523 = 3 Step 2, servo 9 = 1000 @524 = 232 @525 = 7 Step 2, servo 10 = 2000 @526 = 208 @527 = 9 Step 2 to step 0 time = 2400 @528 = 96 The EEW command to write the time/pulse width list is EEW -509, 9,96,5,220,5,220,2,88,3,232,5,220,4,176,3,232,7,208,9,96 Sequencer Commands These are the commands that allow you to play programmed sequences.
PAGE 7
The PA value specifies the length of a pause that is inserted between steps in the sequence. The value is in milliseconds. If PA is not specified, it defaults to 0. The ONCE option specifies that the sequence is played only one time, and then the player stops. The servos will start and end at the position specified by the IX parameter (or 0 if IX is not specified). If ONCE is not specified, the sequence will repeat continuously until the player is stopped by a user command.
PAGE 8
Examples of Sequencer Commands Start player 0 playing sequence 5. Start at step 0, 100% forward speed, no pause between steps, play continuously. PL 0 SQ 5 Change the speed of player 0 to 50% reverse speed. PL 0 SM -50 Pause player 0 (set the speed to 0) PL 0 SM 0 Change the speed of player 0 to 200% forward speed. PL 0 SM 200 Change the pause between steps for player 0 to 1000ms (1 second). PL 0 PA 1000 Stop player 0. PL 0 Go to step 3 of sequence 20.