BASIC stamp manual v2.2

5: BASIC Stamp Command Reference – OWOUT
BASIC Stamp Syntax and Reference Manual 2.2 • www.parallax.com • Page 307
Figure 5.24: OWOUT Reset and
Presence Pulse.
BASIC Stamp’s
Reset Pulse
Apx. 564 s
µ
Device’s
Presence
Pulse
60 - 240 s
µ
Resting State
15 - 60 s
µ
driven by BASIC Stamp
driven by 1-wire device
+5 (vdd)
0 (vss)
This reset pulse is controlled by the lowest two bits of the Mode argument
in the OWOUT command. It can be made to appear before the ROM
Function Command (ex: Mode = 1), after the Transaction/Data portion (ex:
Mode = 2), before and after the entire transaction (ex: Mode = 3) or not at all
(ex: Mode = 0). See the section on Mode, above, for more information.
Following the Initialization part is the ROM Function Command. The
ROM Function Command is used to address the desired 1-Wire device.
Table 5.72 shows common ROM Function Commands. If only a single
1-wire device is connected, the Skip ROM command may be used to
address it. If more than one 1-wire device is attached, the BASIC Stamp
will ultimately have to address them individually using the Match ROM
command.
Table 5.72: OWOUT ROM
Function Commands.
Command Value (in Hex) Action
Read ROM $33
Reads the 64-bit ID of the 1-Wire device. This command
can only be used if there is a single 1-Wire device on the
line.
Match ROM $55
This command, followed by a 64-bit ID, allows the BASIC
Stamp to address a specific 1-Wire device.
Skip ROM $CC
Address a 1-Wire device without its 64-bit ID. This
command can only be used if there is a single 1-wire
device on the line.
Search ROM $F0
Reads the 64-bit IDs of all the 1-Wire devices on the line.
A process of elimination is used to distinguish each
unique device.
The third part, the Memory Function Command, allows the BASIC Stamp
to address specific memory locations, or features, of the 1-wire device.