27961 Parallax Inc, 27961 Datasheet - Page 13

• Manufacturer Part Number: 27961
• Description: MODULE MOTOR MIND SIP
• Manufacturer: Parallax Inc

Specifications of 27961

• Product: Microcontroller Accessories
• Operating Supply Voltage: 6 to 36 V
• Board Size: 30.48 mm x 25.4 mm
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Motor Mind B enhanced
Data Sheet
4.8 SPDCON Command
SPDCON command consists of the sync byte, command byte, and the desired frequency (0 to 65,535)
sent as two bytes, after the desired frequency a GATETIME value may be appended to the command
(but the GATETIME is not used by the MMBe). This command compares the desired frequency with the
actual frequency of the signal at the TACH_IN pin. It then adjusts the motor speed based on the
difference between the desired and actual frequencies (frequency error). The MMBe applies motor
speed changes in an effort to maintain the desired frequency. There are two modes of operation. The
user may also change the operating mode by sending the SPDCON_MODE command.
Increment/Decrement Mode: This is the default mode, and is compatible with earlier versions of the
MMB. In this mode the motor speed is incremented or decremented based on the frequency error. This
mode is slow to respond to changes in the motor load, but also unlikely to overcompensate for small load
changes. Motor SPEED adjustments occur 8 times per second.
PI Mode: More detailed descriptions of the Proportional Integral (PI) Filter occur earlier in this datasheet.
But this mode of speed control will provide a much more responsive speed control. The PTERM, ITERM,
and PISCALAR, associated with PI operation may be modified with the WRITE_PI command. It is
recommended that the 15.5KHz PWM setting be used with PI mode.
The frequency at the TACH_IN pin may be read with the SPDCON_FREQ command. SPDCON mode is
exited by sending any command other than SPDCON or SPDCON_FREQ.
4.9 STATUS Command
The STATUS command is used to read the STATUS byte and SPEED byte from the MMBe. Reading the
STATUS byte allows you to determine if fault conditions have occurred, find out which direction the motor
is turning, and a number of other things. Reading the SPEED register can be useful upon exiting
SPDCON mode to see what the current drive state of the motor is.
The contents of the STATUS register are broken down into individual bits that may be read. All bits in the
STATUS register are factory programmed to 0. A bit that is set is equal to “1”, cleared is equal to “0”.
The CHANGE_FREQ, CHANGE_BAUD, and SPDCON_MODE commands modify bits in the STATUS
register. When these commands are used the new contents of the STATUS register are written to
EEPROM and the new settings are loaded on future power-ups.
CHANGE_FREQ command to set the STATUS.FREQLOW bit, you do not need use it each time the
device powers up. Sending the command a second time would clear the STATUS.FREQLOW bit.
Example of STATUS Command with FAULTON set and SPEED = 128(0x80)
Decimal
Send
Hex
Example of SPDCON Command with frequency of 10,000Hz (0x2710)
Phone: [phone] - www.solutions-cubed.com
Sync
0x55
85
Motor Control System - Solutions Cubed, LLC
Decimal
Decimal
Send
Receive
Hex
Hex
Command
0x04
4
Sync
0x55
Status
85
0x02
2
FreqHi
0x27
39
Command
Speed
0x05
0x80
128
5
FreqLo
0x10
16
For example, if you use the
GateTime
(optional)
0x40
64
Solutions Cubed
Page 13