FTDI chip work as a com1 device

Started by Gary Tolley May 29, 2007
Hi everyone,
I just had to do an upgrade of my motherboard, but I overlooked one
little thing, it didn't have an RS232 header.

I found this device, and the circuit seems straight forward, but I
would like to know if it can be setup as a com1 device?

If it does, i'll start making an internal adapter based off of the
FT232RL device.

Thanks
Gary T
----------
> FT232RL device.

Yes, this commonly-used USB-RS232 converter can be connected to a
BX-24's COM1 port easily. An example: Parallax sells a Prop Plug
http://www.parallax.com/detail.asp?product_id2201, when modified
slightly, works perfectly for downloads and testing with a simple (but
very small) modification.
http://www.zbasic.net/forum/attachments/files/dscn4391a_616.jpg

As supplied, the Plug's /RES pin yields an open-collector active-low
pulse when the onboard FT232R DTR# pin goes high. Even with a pullup,
that won't successfully act as ATN. It's easy (with small tools),
though, to remove a 10nF series capacitor and connect the DTR# output
through an (optional) 150ohm resistor to the module's /RES pin. That
provides a level output for ATN control. +5v can also be taken from
the USB connector to power the processor, within 100mA total.

FTDI's current MProg v2.9c can program the FT232R outputs to either
sense; I found that inverting all three (TXD, RXD, DTR#) works
correctly. You can also change the Product Description field to rename
your custom USB adapter module.

Many folks have incorporated the FT232R into a design. Works great,
and an FTDI utility, MProg, permits changing signal senses and some
pin assignments.
Tom
> FT232RL device.

Yes, this commonly-used USB-RS232 converter can be connected to a
BX-24's COM1 port easily. An example: Parallax sells a Prop Plug
http://www.parallax.com/detail.asp?product_id2201 , when modified
slightly, works perfectly for downloads and testing with a simple (but
very small) modification.
http://www.zbasic.net/forum/attachments/files/dscn4391a_616.jpg

As supplied, the Plug's /RES pin yields an open-collector active-low
pulse when the onboard FT232R DTR# pin goes high. Even with a pullup,
that won't successfully act as ATN. It's easy (with small tools),
though, to remove a 10nF series capacitor and connect the DTR# output
through an (optional) 150ohm resistor to the module's /RES pin. That
provides a level output for ATN control. +5v can also be taken from
the USB connector to power the processor, within 100mA total.

FTDI's current MProg v2.9c can program the FT232R outputs to either
sense; I found that inverting all three (TXD, RXD, DTR#) works
correctly. You can also change the Product Description field to rename
your custom USB adapter module.

Many folks have incorporated the FT232R into a design. Works great,
and an FTDI utility, MProg, permits changing signal senses and some
pin assignments.
Tom
Hi Tom,

Thanks for that, now I can go an get the chip without worry :)
Gary T
> > FT232RL device.
>
>Yes, this commonly-used USB-RS232 converter can be connected to a
>BX-24's COM1 port easily. An example: Parallax sells a Prop Plug
>http://www.parallax.com/detail.asp?product_id2201
>, when modified
>slightly, works perfectly for downloads and testing with a simple (but
>very small) modification.
>http://www.zbasic.net/forum/attachments/files/dscn4391a_616.jpg
>
>As supplied, the Plug's /RES pin yields an open-collector active-low
>pulse when the onboard FT232R DTR# pin goes high. Even with a pullup,
>that won't successfully act as ATN. It's easy (with small tools),
>though, to remove a 10nF series capacitor and connect the DTR# output
>through an (optional) 150ohm resistor to the module's /RES pin. That
>provides a level output for ATN control. +5v can also be taken from
>the USB connector to power the processor, within 100mA total.
>
>FTDI's current MProg v2.9c can program the FT232R outputs to either
>sense; I found that inverting all three (TXD, RXD, DTR#) works
>correctly. You can also change the Product Description field to rename
>your custom USB adapter module.
>
>Many folks have incorporated the FT232R into a design. Works great,
>and an FTDI utility, MProg, permits changing signal senses and some
>pin assignments.
>
>Tom