To use for "write-thru", it is necessary to run a program on the pic16x84. To be able to run this program, the pic16x84 needs +5V on /MCLR, so an additional switch is added (run switch).
- DB9 - PIN
(BLUE) 10K
- 3 - TxD --+--VVVVV-----+--------------------> /MCLR (4)
(blue) | |
| * /
| /
< / RUN switch
< 2K2 *
< |
< |
| |
| |
+------------+
|
| |\|
+-----| |--------+----------------> Vdd +5V (14)
| |/| |
__|_/ 1N4148 ===== +
/ / \ =====
/ \ 5V6 | 100uF
--+-- |
| | (WHITE)
- 5 GND --+----------------+-----------------> Vss (5)
(shield) |
///
22K (GREEN) CLOCK
- 7 RTS ------VVVVV----+---------------------> OSC1(16),RB6
2.2K (ORANGE) DATA
- 4 DTR ------VVVVV----+---------------------> RB7 (13)
| black
|
- 8 CTS ---------------+
|
__|__
/ \ -->
/ \ --> LED
--+--
+5V |
Vdd---VVVVVV---+
2K2 or more
As an extra precaution I have added additonal 5V1 zenerdiodes
on RB7 and OSC1 (not showed above).
If your computers serial interface does not supply voltages near +/- 12V,
the LED may be omitted.
Connect an extra "run" switch as shown:
Actually temporarly just connecting the two points will do the job, adding an extra switch to the board is just for convenience.