ATN pin connection on BX-35

Started by church_art October 16, 2005
There was some discussion here on using 10K resistors instead of 100K
resistors for connecting the ATN line to pin 4 and to ground. Is this
true for both of them , one of them or none ? Thanks ( Im using
suggested BX35 schematic from BasicX )
I am also assuming the disconnect for operational should be between
pin 4 and the resistor to the ATN pin2 of the BX35. True ?

Also thanks for the help on PCB design.

Art



--- In basicx@basi..., "church_art" <achurch@m...> wrote:
>
> There was some discussion here on using 10K resistors instead of 100K
> resistors for connecting the ATN line to pin 4 and to ground.
> Is this true for both of them , one of them or none ?

It seems one is 10k [to ground] and one is 100k[to pin 4]. You can
read my Errata file on the BX35 in the group's FILES section, but below
is a quicker solution.

( Im using > suggested BX35 schematic from BasicX )

I would strongly recommend that you DON'T. Use the design on the
BasicX Development Board instead, because the BX35 documents are
PRELIMINARY and I am not sure anyone ever built that design. The
development board is working and in use by many AND supports the BX-35.

> I am also assuming the disconnect for operational should be between
> pin 4 and the resistor to the ATN pin2 of the BX35. True ?
>
The development board has an optional disconnect for the ATN pin in the
appropriate location.

It allows you to use the Tx and Rx as a proper RS-232 port after you
completely program the BX-35. Keep in mind that the BX-35 is TTL and
not true RS-232 [like the BX-24]. So you have to wire up a Max232 to
gain +10/-10 signals and to invert the signal properly.



--- In basicx@basi..., "G. Kramer Herzog" <hwanghetw@y...>
wrote:
> Keep in mind that the BX-35 is TTL and not true RS-232 [like the
> BX-24].

For the sake of accuracy, it should be noted that the BX-24's serial
out line does not conform to the RS-232 standard. It has a voltage
swing, at best, of 0V to 5V. The RS-232 standard specifies voltages
in the range -3V to -15V for a "mark" (logic 1) and +3V to +15V for
a "space" (logic 0).

That said, the levels generated by the BX-24 seem to be interpreted as
expected by a typical PC.

Don