27906 Parallax Inc, 27906 Datasheet - Page 7

• Manufacturer Part Number: 27906
• Description: BASIC STAMP ACT BOARD NO PWR
• Manufacturer: Parallax Inc

Specifications of 27906

• Module/board Type: Activity Board
• For Use With/related Products: BASIC Stamp®
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

QSPD – Query Speed
Description: Returns the current average speed in positions/0.5 sec. This is a signed 16-bit number.
CHFA – Check for Arrival
Description: Checks to see if the device has arrived at its destination within a specified position
TRVL – Travel Number of Positions
Description: This command advances the end point by “Number” of positions. Number is a signed 16-
Copyright © Parallax Inc.
Command #
Command #
Command #
[Command:Address],[NumberH],[NumberL]
2
4
3
[Command:Address],[Tolerance]
Transmit Data Format
Transmit Data Format
The current speed value is updated every 20 ms and is an average over the previous 0.5
second. The value is returned high byte first (ValueH) then low byte (ValueL).
It is important to note that this is an average speed value, not the instantaneous speed of
the wheel. The difference is most noticeable when the speed changes abruptly. For
example, if a speed of 10 positions/0.5 second instantly increases to 30 positions/0.5
second, the average speed value will immediately start increasing, but will take up to 0.5
second to register the new actual speed.
uneven terrain since the overall average speed is usually more meaningful than a
fluctuating instantaneous speed reading.
tolerance. The position tolerance value can be 0 to 255, and must be specified in the byte
directly following the command code. This function will return “True” (0xFF) if the current
average speed is zero, and the current position matches the end point within ± the
position tolerance value. Otherwise this function will return “False” (0x00).
bit value sent high byte first (NumberH) then low byte (NumberL). Any time the end point
is moved away from the current set point, the Position Controller will accelerate at the
speed ramp rate (see SSRR command) to the set maximum speed (see SMAX command)
and automatically decelerate just in time to stop at the exact end point.
TRVL commands are accumulative.
positions followed immediately by another command to travel +130 positions is equivalent
to sending a single command to travel +330 positions. Likewise, a command to travel
Transmit Data Format
{-32768 ≤ Number ≤ 32767}
[Command:Address]
{0 ≤ Tolerance ≤ 255}
Hex Value
Hex Value
Hex Value
0x10
0x20
0x18
Position Controller Kit (#27906)
Binary Value
Binary Value
Binary Value
00010 000
00100 000
00011 000
For example, sending a command to travel +200
This can be beneficial when traveling over
{Value = 0xFF (True); Value = 0x00 (False)}
Receive Data Format
Receive Data Format
Receive Data Format
Command Category/Type
Command Category/Type
Command Category/Type
[ValueH],[ValueL]
Action
Query
Query
[Value]
N/A
v1.1 3/22/2010 Page 7 of 13
Single, All
Single
Single