Parallel Port Band Code Translator

This project has been rendered unnecessary by changes in WriteLog. It is being kept on the site as an example of a very simple Parallax Propeller application.

The problem is a simple one. WriteLog used one set of binary codes for the LPT band switch output for 50 MHz through 24 GHz, and my station, based on the PackRats' N3FTI Logging Band Interface, used another set of binary codes. And I REALLY wanted to use WriteLog, and didn't want to have to rewire my bandswitch. So I quickly wrote up the plans for this simple decoder or translator, which is simply inserted inline with the LPT cable that runs between the WriteLog computer and my bandswitch. However, Wayne K5XD is so very responsive to users' input, that before the parts for this device were even shipped to me, he had modified WriteLog to take care of this problem. Nevertheless, I leave this here as a very simple example of what can be done with a Parallax Propeller chip.

The propeller takes input from the LPT port of the computer and recodes it to what the N3FTI board needs and sends the required output to the N3FTI board. The program is written so that if the input band code changes, it is a simple matter to reassign the 0-15 input codes to the output band codes F50 through F24G. A 74LS75 Latch is used to keep band switching from occurring while the station is transmitting. The 74LS75 Latch can be placed on either the input or output side of the Propeller. PS2505 Optoisolators on protect the Propeller chip. A preliminary schematic is here.

The code is listed below, and also in this hyperlink. The first two-thirds or so are just documentation:

{{ LPTCode.spin
Band Coding Converter by W3SZ Jan 2, 2008
Takes arbitrary 4-bit LPT input and outputs 4-bit code to match standard of N3FTI, PackRats Logging Interface Board

The input signal matrix from WriteLog is as follows:

Band	A	B	C	D
160	1	0	0	0
80	0	1	0	0
40	1	1	0	0
30	0	0	1	0
20	1	0	1	0
17	0	1	1	0
15	1	1	1	0
12	0	0	0	1
10	1	0	0	1
50	0	1	0	1
144	1	1	0	1
222	0	0	1	1
432	1	0	1	1
903	0	1	1	1
1296	1	1	1	1
2304	1	0	0	0
3456	0	1	0	0
5760	1	1	0	0
10G	0	0	1	0
24G	1	0	1	0
47G	0	1	1	0
75G	1	1	1	0
119G	0	0	0	1

A = LPT pin 2 Least Significant
B = LPT pin 7
C = LPT pin 8
D = LPT pin 9 Most Significant
Gnd = LPT pin 15

The output signal matrix is as follows:

Band	A	B	C	D
50	0	0	0	0
144	1	0	0	0
222	0	1	0	0
432	1	1	0	0
903	0	0	1	0
1296	1	0	1	0
2304	0	1	1	0
3456	1	1	1	0
5760	0	0	0	1
10G	1	0	0	1
24G	0	1	0	1
Others	0	0	0	0

A = LPT pin 2 Least Significant
B = LPT pin 7
C = LPT pin 8
D = LPT pin 9 Most Significant
Gnd = LPT pin 15

LPT Pin 2 connects to Pin 0
LPT Pin 7 connects to Pin 1
LPT Pin 8 connects to Pin 2
LPT Pin 9 connects to Pin 3

Pin 11 connects to LPT Pin 2 out
Pin 12 connects to LPT Pin 7 out
Pin 13 connects to LPT Pin 8 out
Pin 14 connects to LPT Pin 9 out

END OF DOCUMENTATION; code follows:
}}

VAR
     long temp[4]
     long freq
     long stack[9]

PUB Main

      cognew(toggle(3_000_000), @stack)
      convlpt

PUB toggle(Delay)
     dira[16]~~
     repeat
        !outa[16]
        waitcnt(Delay + cnt)

PUB convlpt
  dira[11..15]~~
    dira[0-3]~
    repeat
       temp:=INA[3..0]
       freq := temp[0] + (2*temp[1]) + (4*temp[2]) + (8*temp[3])
       case freq
          '0
          1: F2304
          2: F3456
          3: F5760
        4: F10G
          5: F24G
          ' 6: F47G
          ' 7: F75G
        ' 8: F119G
        ' 9: F142G
          10: F50
          11: F144
        12: F222
        13: F432
        14: F903
        15: F1296
      OTHER: F50

PUB F50
      outA[11..14]:= %0000
PUB F144
      outA[11..14]:= %0001
PUB F222
      outA[11..14]:= %0010
PUB F432
    outA[11..14]:= %0011
PUB F903
    outA[11..14]:= %0100
PUB F1296
    outA[11..14]:= %0101
PUB F2304
      outA[11..14]:= %0110
PUB F3456
    outA[11..14]:= %0111
PUB F5760
      outA[11..14]:= %1000
PUB F10G
      outA[11..14]:= %1001
PUB F24G
      outA[11..14]:= %1010

Brought to you by the folks at W3SZ