Parallax BASIC Stamp 2e - Page 298

SEROUT - BASIC Stamp Command Reference
Page 296 • BASIC Stamp Programming Manual 2.0b • www.parallaxinc.com
On the BS1, serial communication is limited to: no-parity, 8-data bits and
1-stop bit at one of four different speeds: 300, 600, 1200 or 2400 baud.
Table 5.80 indicates the Baudmode value or symbols to use when selecting
the desired mode.
Baudmode
Value
Symbol Baud Rate Polarity and
Output Mode
0 T2400 2400 TRUE (always driven)
1 T1200 1200 TRUE (always driven)
2 T600 600 TRUE (always driven)
3 T300 300 TRUE (always driven)
4 N2400 2400 INVERTED (always driven)
5 N1200 1200 INVERTED (always driven)
6 N600 600 INVERTED (always driven)
7 N300 300 INVERTED (always driven)
8 OT2400 2400 TRUE (open drain, driven high)
9 OT1200 1200 TRUE (open drain, driven high)
10 OT600 600 TRUE (open drain, driven high)
11 OT300 300 TRUE (open drain, driven high)
12 ON2400 2400 INVERTED (open source, driven low)
13 ON1200 1200 INVERTED (open source, driven low)
14 ON600 600 INVERTED (open source, driven low)
15 ON300 300 INVERTED (open source, driven low)
On the BS2, BS2e, BS2sx and BS2p, serial communication is very flexible.
The Baudmode argument for SEROUT accepts a 16-bit value that
determines its characteristics: 1-stop bit, 8-data bits/no-parity or 7-data
bits/even-parity and virtually any speed from as low as 300 baud to
greater than 100K baud (depending on the BASIC Stamp). Table 5.81
shows how Baudmode is calculated and Tables 5.82, 5.83 and 5.84 show
common baud modes for standard serial baud rates.
Step 1: Determine the
bit period (bits 0 – 11)
BS2 and BS2e: = INT(1,000,000 / baud rate) – 20
BS2sx: = INT(2,500,000 / baud rate) – 20
BS2p: = INT(2,500,000 / baud rate) – 20
Note: INT means 'convert to integer;' drop the numbers to the right of the
decimal point.
Step 2: Set data bits
and parity (bit 13)
8-bit/no-parity = 0
7-bit/even-parity = 8192
Step 3: Select
polarity (bit 14)
True (noninverted) = 0
Inverted = 16384
Step 4: Select driven or
open output (bit 15)
Driven = 0
Open = 32768
Table 5.80: BS1 Baudmode
Values.
Table 5.81: BS2, BS2e, BS2sx and
BS2p Baudmode calculation. Add
the results of steps 1, 2, 3 and 4 to
determine the proper value for the
Baudmode argument.
1
2
e
2
sx
2
p
2