Connecting the CF-III Sound

Any sound system that responds to my droid sound command language and can handle a serial connection at 9600 bauds will work with the MarcDuino. One such system is the CF-III Sound loaded with my program as described here. It is a pricier sound setup than with the Sparkfun MP3Trigger, but it has the advantage of having a nice integrated amplifier in a clean package. This section explains how to connect a CF-III system to the MarcDuino.

Note that the MarcDuino must be loaded with a different firmware image when using the CF-III system (currently PanelController_CFIII_v1.6.hex found here).

A level adapter is needed between the UART 5V level interface of the MarcDuino and the 12V RS-232 interface of the CF-III sound.
Beware, you need the better models that actually generate the RS-232 voltages on its own, like this one from Schmartzboard:

The cheaper ones, like this one from SparkFun, tries to steal their negative power supply from the RS-232 link, and did NOT work reliably with the CF-III.

Older CF-III Systems with Female DB9 Connector

Until recently, the CF-III sound had a female DB9 connector. For these older systems you need either

- a Null-modem adapter cable with male ends (not easy to find) between the level adatper and the CF-III

- or a DB9 male-male gender changer between the level adapter and the CF-III, and switch the JB2 jumpers orientation.

That allows to simply plug the level adapter right into the CF-III, which is nicer. However you need to switch the J2 jumper config, see below.

First Google "DB9 gender changer" and choose a male to male adapter. For example this one:

Then open up the unit, and change the orientation of the jumpers next to the serial port so they are perpendicular to the IC nearby:

Plug the gender adatper in the CF-III serial socket, then the Sparkfun level adapter into the gender adapter.

Recent (after late 2013) CF-III Systems with Male DB9 Connector

Recent systems (as of Sept. 2013) have a different serial port configuration. The socket in the CF-III has been changed to male, and the jumpers have disappeared.

The boards now look like this, no headers or jumpers on JB2:

So if you have the newer units, you'll need either:

- a Null Modem cable adapter with female ends, and a male to male DB9 gender adapter.

Connect everything like this:

Here is the detail of the pins on the level adapters, the PC4 wire from the MarcDuino connects to the Rx pin on the level adapter:

- or nothing at all, if you are comfortable modifying the board back to the older configuration.

This leads to a cleaner installation. You won't need the Null Modem cable nor the gender changer.

In order for this to work, you first have to sever the two traces on the back of the circuit board between the pins of the jumper. The traces were obviously added as a permanent connection instead of the previously modifiable jumper configuration. We need to get rid of them to jumper it the other way. I used a light application of a Dremel cutting wheel to cut the two traces off:

Then install the missing headers in JB2 on the other side and jumper it like below. Now just plug the level adapter straight in, nothing else necessary.