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In the normal development of any project or design there are
changes before the next version is complete. This list applies to
the board design variations.
| Device |
Change |
Reason |
| U3 |
Add 100K
resistor to pin 12 |
pull
down to prevent floating |
| ISP
|
keep
cable very short, ~ 2 feet |
prevent
noise |
| S1 |
rotate
switch 90 degrees |
contact
alignment |
| S2 |
rotate
switch 90 degrees |
contact
alignment |
| JP18 |
do not
install |
misaligned & not used |
| DS1 |
remove
7-segment when use LCD |
use same
control lines & mechanical space |
| Serial |
connector requires female |
|
| C9 |
replace
with wire |
not used
with Max235 chip |
| Peel |
Pin 10
is WRn |
mislabeled |
| Peel |
Pin 11
is RDn |
mislabeled |
| U1 |
Pin 16 is WRn |
mislabeled |
| U1 |
Pin 17 is RDn |
mislabeled |
| Book |
Schematic & Peel |
versions available at print
time |
The board has many options for further
development and projects. The following items are not required for
the current set of projects.
| Component |
Action |
Reason |
| LCD contrast |
place jumper from LCDCT to gnd |
contrast auto adjust not used |
| JP18 |
remove |
spare IO |
| RS485 |
remove |
using RS232 only |
| R11 |
replace resistor with wire |
EA' connect for internal only |
| RS232 handshake |
remove |
not used |
| GenMem |
remove components |
use internal memory only |
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