USB I2C Interface (BETA) 02_External Connections

Install USB Cable

• 
• Solder a short length of bus wire to the strain relief hole on the board (yellow hole, centered between holes 2 and 3 on the left-hand side of the board).
• 
• Solder the 4 leads of the USB cable to the holes (1, 2, 3, and 4): The leads should correspond in color
  • 1=RED
  • 2=WHITE
  • 3=GREEN
  • 4=BLACK
  as indicated in the associated photo (above).
  • Wrap the strain relief wire firmly around the cable so as to let the bus wire take all the cable strain and protect the 4 USB leads from stresses/strains
  • At this point, we can also plug in the ATTiny 85-20PU microprocessor chip that affects the control of the rig. The initial versions of this kit used the less capacious ATTiny 45-20PU and were programmed with an early version of the firmware. Current versions of the kit include (as of October 2009) the ATTiny 85-20PU chip with Fred PE0FKO's firmware version 15.12. That firmware can be configured to control all of the functionality of the RXTX V6.3 or the Automatic Bandpass Filter functionality of the Lite + Xtall RX V9.0. See Bob G8VOI's User Guide on configuring this chip and Fred PE0FKO's guide on obtaining running the configuration software.

  Check	Designation	Component	Marking	Category	Orientation	Notes
  ❏	cbl	USB 4 conductor 3' male		cable
  ❏	U1	ATtiny 85-20 PU w/N15.12 Firmware	AVR ATTINY85-20PU	DIP 8		Take ESD precautions Do not plug into sockect SO1 until first voltage test is completed.

Install I2C control bus connector

The I2C protocol for control of the Si570 requires two lines (in addition to a common ground line):

• The Clock line ("SCL") which provides clocking signals for Input Output data
• and the bidirectional serial data line ("SDA"), which carries output/input serial data across the interface.

Here, we will provide the connection over which the I2C control signals will move to the controlled rig (RX V8.3 or RXTX V6.3). You will have a choice of a NON-PERMANENT or a PERMANENT installation, as described below:

• A non-permanent connection, via soldering the cables into the top of the 8 pin machined socket provided in the kit for that purpose. In this latter case that socket, SO2, will act as a "plug" which can be plugged into the corresponding socket on the interfaced rig, as shown in the large interconnect image above that shows the USB_I2C mated to the RXTX V6.3.
• A permanent connection, to the RXTX, via direct soldering to holes provided on the RXTX board.

Non-Permanent Connection

• 
• Select hookup wire whose diameter will fit into the small holes at the top of SO2
• Solder three 6" to 8" wires to the holes marked "DA" and "CL" and the unmarked (ground) hole below the "DA" hole in the upper right-hand corner of the board, as shown above. These correspond to the SDA data line ("DA") and the SCL clock line ("CL" signals which will control the Si570 on the V8.3 RX board or the V6.3 RXTX board.
  The wire length should be chosen to fit your situation (but should be equal to the length used for the PTT control connection).
• Solder the other ends of the three wires to the 8 pin socket SO2, which will serve as a "plug" to mate with the 12F683's socket on the interfaced rig. Note that this SO2 is provided in the USB I2C kit. Do NOT try to solder the three wires directly into the interfaced rig's 12F683 socket:
  • Solder the SCL ("CL") wire to the TOP of SO2 at the hole for pin 2
  • Solder the SDA ("DA") wire to the TOP of SO2 at the hole for pin 3
  • Solder the ground wire to the TOP of SO2 at the hole for pin 8
• This will allow you to remove the 12F683 chip from its socket on the RX (U3) or RXTX (U6) board and replace it by plugging SO2, with its 3 leads, into the empty socket (carefully aligning the notched ends of the sockets).

Permanent Connection

• If you plan to use the interface permanently with your RXTX V6.3, you can dispense with SO2 and, instead, remove U6 (12F683) and SW1 from the RXTX board and solder the three leads to the corresponding holes (see photo below) in the SW1 footprint on the RXTX V6.3 board.
• 
  
  Showing the permanent connection to the three connect holes in the RXTX board (under SW1).

Check	Designation	Component	Marking	Category	Orientation	Notes
❏	control cable wire	misc hookup wire		misc		3 short lengths of hookup wire (not provided with kit)
❏	SO2	socket, machine, 8 pin		socket

Install PTT control line (optional)

The SRv6.3 PTT_I was designed to be activated with +12V from the RS232C signal of the Rocky Interface, OR with +5V from other sources (e.g. a +5V uC signal, such as from the USB I2C board). Because you will have already connected the I2C bus's ground to the RXTX board, there is no need for an additional GND connection tor the PTT control, as the GND return may flow through the I2C bus.

The USB I2C interface schematic shows that the PTT_OUT (Rx = 0V, Tx = 5V) is to be connected to the SRv6.x. Although not stated in the schematic, the connection is to SRv6.x's PTT_IN.

• 
  USB I2c Board
  USB I2C Board - PTT Connection
• Connect a 6" - 8" length of wire to the PTT hole at the bottom right of the USB I2C board. The wire length should be chosen to fit your situation (but should be equal to the length used for the I2C bus connection).
• 
  RXTX V6.3 Board
• This will connect to the "PTT-I" hole on the RXTX board. You may want to use a connector arrangement in cases where you want the USB I2C Interface to be used on multiple Si570-driven RXTX and/or RX

Install keyer connection (optional)

Connect three wires of appropriate length to the K1, K2, and ground leads and a suitable connector to the other end, such that your keyer inputs (and ground) can be fed to the USB I2C Interface board. The wire lengths should be chosen to suit your situation.

Note: The K1 input is for the DOT paddle and the K2 input is for the DASH paddle.

Apply heat shrink tubing (optional)

Tony supplies a piece of heat shrink tubing to allow you to encapsulate the completed board in a protective shield