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Step 13Serial Add-On
Most of the serial add-on components have already been installed. There is one important item to address.
J34 dictates where the serial RS232 IC draws power from... the application circuit or the power supply add-on. You have two choices, use a jumper wire (as we did with U6 of the previous step) or install a pin-header. A jumper wire is more of a permanent choice, I would prefer to have options later so I'm installing a pin-header. I had enough pins left over from the Basic Parts kit to put a 1x3 header in this location.
1. Install the DB9 connector
In order use the serial capability of this serial add-on you must connect to a microcontroller. There are a couple of ways to do this, including soldering jumper wires in place for a permanent connection. I prefer to leave my options open so I have installed two small pin-sockets that I can connect with wire-jumpers and avoid soldering in the future. These pin sockets are not included in any of the Ecros Tech parts kits.
For normal operation, solder a wire between the two solder pads marked "TXD" as well as the two solder pads marked "RXD" (see picture below). In the pictures below you can see where I have mounted pin sockets. This will allow me to easily connect these with a wire-jumper that can be changed in the future. It also leaves me the option of using this serial functionality with off-board circuits (for prototyping).
J34 dictates where the serial RS232 IC draws power from... the application circuit or the power supply add-on. You have two choices, use a jumper wire (as we did with U6 of the previous step) or install a pin-header. A jumper wire is more of a permanent choice, I would prefer to have options later so I'm installing a pin-header. I had enough pins left over from the Basic Parts kit to put a 1x3 header in this location.
1. Install the DB9 connector
- Connector will "snap" into place on the board
- Solder all of the data pins
- The two "clips" that snapped into the large holes should also be soldered. These work as a mechanical connection so load them up with solder.
- To leave your options open, solder a 1x3 pin header here and use a shunt for selection.
- To always power the serial chip from the PSU Add-on, solder a wire between pin1 and pin2.
- To always power the serial chip from the AVR circuit power rails, solder a wire between pin2 and pin3.
- If you previously installed a 16-pin socket at U8, simply insert the IC into this socket.
- If you chose not to use a socket, insert the IC paying attention to the notch for orientation. Solder each pin and clip the excess.
In order use the serial capability of this serial add-on you must connect to a microcontroller. There are a couple of ways to do this, including soldering jumper wires in place for a permanent connection. I prefer to leave my options open so I have installed two small pin-sockets that I can connect with wire-jumpers and avoid soldering in the future. These pin sockets are not included in any of the Ecros Tech parts kits.
For normal operation, solder a wire between the two solder pads marked "TXD" as well as the two solder pads marked "RXD" (see picture below). In the pictures below you can see where I have mounted pin sockets. This will allow me to easily connect these with a wire-jumper that can be changed in the future. It also leaves me the option of using this serial functionality with off-board circuits (for prototyping).
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