The Serial Port is Dead! Long Live the Serial Port!
each time I
and once it
didn’t work for an hour, then just started working almost
as if influenced by my progressively foul language.
(Breadboards are fun!) The following instructions refer to
the schematic shown in Figure 8.
• Wire the ST202EBN level converter using the diagram
shown in Figure 8.
• Place the BBUSB and the ST202EBN on the breadboard
more or less as shown.
• Wire BBUSB for +5V
– Wire USBVCC to VCC
– Wire VCC to breadboard +5V
– Wire VIO to breadboard +5V
– Wire GND to breadboard GND
Wiring this thing up correctly is harder than it appears,
isn’t it? You can test this if you have a computer with both
a USB port and an RS-232 port. Attach both devices and
open two instances of Simple Terminal, then open one
port in one instance and the other in the second one
and begin communicating. This is pretty hard to wire up
correctly, so be patient with your debugging efforts.
• Add the five 0.1 μF caps to the ST202EBN as shown.
Trim the legs to get the caps near the board.
– Cap between +5V and GND, near pins 15 and 16.
– Cap between +5V and pin 2.
– Cap between pins 1 and 3.
– Cap between pins 4 and 5.
– Cap between pin 6 and GND.
Bit-bang Reading Switches and
Despite the markings on the BBUSB, those pins
• Wire TxD of BBUSB to pin 11 of the
• Wire RxD of BBUSB to pin 12 of the
• Wire the DB9 pin 3 (TxD pin) to pin 14 of the
FIGURE 11. Bit-banging
• Wire the DB9 pin 2 (RxD pin) to pin 13 of the
FIGURE 12. Bit-banging LEDs breadboard.
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