• GPIBtoUSB2

GPIB to USB Interface, Elektor 04-2011

English version of the German page GPIBtoUSB.

Rainer Schuster was so friendly, and has programmed in a good style a GPIB to USB converter with Win32 demo program to read a Tektronix TDS210 oscilloscope presented in the magazine Elektor 04-2011. The whole thing is much cheaper than commercial circuits, for hobby purpose.

Unfortunately, by not using a GPIB bus driver, it is only possible to connect not more than one GPIB device. The R8C CPU can deliver up to 60 mA at the I / O ports in total. Per output, but it should not be more than 2 mA in order not to exceed the voltage of 0.8V for the LOW level. With IEEE-488 GPIB standard, each device on the bus has a termination 3 KOhm resistor to +5V and 10 KOhm to 0V.

Development Software

After 5,5 years the Toolchain from Renesas is a little bit scrambled.

Good explanation for beginners: Erste Schritte mit Renesas M16C und GCC (German)

Problems:

• Because in the Release folder no GPIB_USB.MOT file was found, I liked to compile new, following the description from Elektor magazine 12-2005.

• The Monitor/Debugger KD30 could not be installed under Win7-32.

• After the installation of NC30 from Renesas AutoUpdate a new version from HEW was updated, which had a different WorkSpace management.

• At the software GPIB_USB the Workspace File GPIB_USB.hws was missing.

  • The old Workspace Project File GPIB_USB.hwp is no longer valid. In creating a new project file a few questions arised:

    • Heap size = 100

    • Stack size = 80
      

• The IDE HEW (High-performance Enbedded Workshop) did not show the menu Build.

  • This could be fixed by setting up Target = Simulator.

• The Linker ln30 showed an error: ROMDATA' section 'vector' is overlapped on the 'interrupt' from FEDCH to FF68H.

  • proposed change: In file sect30.inc in line 609 change:

      .org 0c800H ; was 0e000H

    Unfortunately this change also changed the Interrupt Vektor Tabelle address. Hence, the data reception no longer works:

  • Solution: By setting up a new project a new file sect30.inc was created, with rom_NE_top = 0e000H. The version in the downloaded ZIP File had the value 0d000H at this location. By the proposed change to 0c800H the Interrupt Vektor for UART1 no longer fitted. After the file sect30.inc was copied from the ZIP archive into the Workspace, the program worked.

• You can find some hints to R8C software problems in Softwareproblemen (German).

Simplified Hardware

Since the R8C Starter Kit (supplement in the 12-2005 Elektor magazine!) was present in the junk box I looked for a suitable USB-Serial cable. At Ebay for only EUR 5 (including shipping) there is a Nokia CA-42 clone (Polific PL2302 chip) available. I ordered it, but it gave the following difficulties:

Now I have learned, that only the cable with the blue USB plug housing (rubber like) does have a pl2303 chip inside. The cable with a black USB plug hard plastic housing does have a seldom used OTI 6858 chip (Ours Technology Inc.), which has drivers for Windows and Linux only. But this one has a DTR line and the USB +5 V readily available.

• On the Serial side the signal voltage is +3.3 V only. Regarding the R8C/13 data sheet minimum +4 V are needed. That was archived with an IC LM339 (Quad Comperator, Reichelt 0,20 EUR).

Test of the circuit

In order to test the basic function of the program and the interface, you need a terminal program. May I suggest PUTTY, it also works on Win 7-32.

PUTTY Parameters, Session:
  Connection Type: serial
  Serial line: COMx (x = USB Serial Emulation Nummer, z.B. 6)
  Speed: 38400

Keyboard input (blind, no Echo): "I", strg"J" (upper case I, Control+J = LineFeed)

Answer:
GPIB/USB converter V1.0

or
Set local echo ON
Text from the clipboard is inserted into the terminal window via the middle mouse key.

or with the MAC OS X Terminal (sudo because of /var/spool/uucp access):
$ sudo cu -l /dev/cu.PL2303-0000103D -s 38400
Help for "cu" (Call Up another system):
    ESCAPE: strg + alt gr + N = ~
    Terminate: ~.
    Variable: ~v
    Commands: ~?
    \ = SHIFT + alt + 7

All that was tested under Virtual Box V.4.0.6 in MAC OS X 10.6.

Firmware Comands

The commands can be sent manually in a terminal to the GPIB-USB converter. All commands must be terminated with Linefeed (Ctrl + J).

• C - Reset and Init GPIB Bus

• Gx - Send Command byte, x = Zahl 0..255

• I - Show the GPIB-USB info : GPIB/USB converter V1.1

• Ra,s - Send a string and read answer, a = GPIB Adresse, s = String, end of read at LineFeed

• S - Check GPIB SRQ signal

• Tn - Set GPIB Timeout in n = ms

• Wa,s = a = GPIB Address, s = String, Write a string

Changes in the Firmware

Unfortunately there is a bug in the file GPIB_functions.c.

• Cause: Since the port 0 bit 0 is used for the serial interface (TXD), the data must be shifted by 1 to the left. The bit 7 is output via Port 3, Bit 1. Because unfortunately it is pushed first and then tested for bit 7, all ASCII characters > 0x3F get bit 7 set. Some GPIB participants will correct that without complaint. My logic analyzer HP1631D does not.

• Solution: In program GPIB_functions.c in function send_gpib_byte() the command sequence must be:

        if (data & 0x80) p3_1=0; else p3_1=1;
        data = data <<1; //shift to p0_1..p0_7
        p0= ~data;

Extensions to GPIB_USB.c

To be able to operate my HP Logic Analyzer HP1631D in a useful manner with this interface a few commands were added:

• B addr, byte LF - send a command Byte to the selected device, for example "B4,1\n" for the command Go To Local, in order to switch from Remote Mode back to Local Mode, in order to operate from the front panel again.

• D LF byte - send a Data byte, if the device was addressed before with the L-command. Which is used to upload a file to the GPIB device.

• E addr, command LF - This works like the R-command, but the end of the answer is not sinalled by a LineFeed, instead with EOI. Otherwise reading in of multi-line data, for example a screen hardcopy, will be more complicated.

• L addr,LF - switching of the selected device to Listener, and uploading a file to the device.

• U LF - switching off the Listener mode, with the sequence: LF+EOI, UNL, UNT. That could also be done with a sequence of other commands, but his is easier in the GPIB programming.

The extended files are here for download: GPIB_USB.c , GPIB_functions.c and binary Release.zip.

Application Program hp1630.py for Logic Analyzer

2016-08-21 Software update - you can find an actual software version here. The renewed program hp1630_p23.py was made compatible for Python 2 and 3, and tested on Linux Ubuntu 16.04-32, Mac OS X 10.11.6 El Capitan, and Windows 7-64. Now it can be used as an example program also for other GPIB instruments.

For comfortable using the HP Logic Analyzer HP1631D, I have written a Python command line program hp1630.py. It actually runs under MAC OS X, but should be easily ported to Win32 or Linux. If you run the programm without parameter you get get a help message. The GPIB Address of the device is coded to 4. The following commands are build in, as Command Line Parameter:

• -a --printall - print the Text Screen, also the non visible part. Filename default: printall.txt

• -b --beep - the Logic Analyzer will generate a Beep.

• -d --date - sets the actual date and time in the Logic Analyzer. The time is incremented (RTC) until switching off the LA. There is no battery back up (27 years old).

• -f --file - specify a Filename for download or upload.

• -i --id - read out the identity info of the device (hp1631D).

• -l --local - switch back the device from Remote mode to Local mode, for using again the front panel buttons. This is also possible by a switch on the front panel, but it could be more convenient.

• -p --print - read out a Waveform screen shot and store in format PBM (Portable Bit Map). OpenOffice can import that file.

• -r --restore - upload the Inverse Assembler for the HP 10269B Preprozessor (GPIB, RS232, RS449). This will show GPIB mnemonics on the screen, up to 1000 cycles.

• -t --timeout - set GPIB timeout in seconds.

• -u --usb read out the Info string "GPIB/USB converter V1.1" from the GPIB-USB converter.

• -v --verbose enable temporarily status messages for debugging.

If you want to run a different GPIB device so you have to adjust the program accordingly. Since Python is a multi-platform interpreter programming language, an adoption should not be so difficult.

Screen Shots

Finally a hardcopy picture from the HP1631D in Waveform mode:

and GPIB analyze text screen (command Beep) with Bus Preprocessor HP10342B and Inverse Assembler (IHPIBc & IHPIBi):

   1 State Listing____________________Data Acquired Apr 13 2007 09:58
   2                                                REMOTE        <|
   3 Label> ADDR          ATN  Mnemonic  HEX EOI  SRQ  REN  IFC  STAT
   4 Base > [HEX]  [                   ASM                    ]  [HEX
   5  
   6 [Mark]   X    [               Instructions               ]   X$
   7  
   8 -0003*   0           ATN   TAG_00   40            REN        DA
   9 -0002*   0           ATN   *UNL*    3F            REN        DA
  10 -0001*   0           ATN   LAG_04   24            REN        DA
  11 +0000    0                   B      42            REN        DB
  12 +0001    0                   P      50            REN        DB
  13 +0002    0                   ;      3B            REN        DB
  14 +0003    0                 <LF >    0A  EOI       REN        D9
  15 +0004*   0           ATN   TAG_00   40            REN        DA
  16 +0005*   0           ATN   *UNL*    3F            REN        DA
  17 +0006*   0           ATN   LAG_04   24            REN        DA
  18 +0007*   0           ATN    GTL     01            REN        DA
  19  
  20  
  21  
  22  
  23  
  24 

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-- RudolfReuter 2011-06-17 08:43:38

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