PicDongle 12A Series users' guide

    Installing PicDongle 12A Digital Sampling System

    The PicDongle 12A series are multichannel data acquisition modules for use with any PC or other computer with a RS232-E serial port interface. The PicDongle is controlled by a low-power RISC microcontroller and requires no handshaking with the host PC. Data is transmitted to the host PC as a constant stream with a frame marker. The frame marker is two bytes of FFh. The A/D sampled data following the frame marker is low byte then high byte for each channel starting with channel 1. After all 8 channel samples (16 data bytes) are sent a new frame marker is transmitted. The host PC controls the data stream with the RTS line. Setting RTS 'high' or +3 to +15 Volts (logic '0' for the RS232) starts the stream and a 'low' stops the stream.

    What the PicDongle Digital Sampling System Contains:

    Windows/DOS/C Starter Code diskette
    PicDongle 12A Series hardware

    What You Need to Get Started:

    1. An IBM-PC or compatible computer equipped with at least one 3 1/2" 1.44 Mbyte floppy disk drive or other computer that can read a IBM-PC 1.44 MByte floppy.

    If you want to run the example software you will need:

    2. Windows 3.x, 95 or PC/MS-DOS 5.0 or later disk operating system, and
    3. Input Transducer: Sensor or Signal source or laboratory test signal generator

    For advanced use of this and other SiliconSoft Digital Sampling Systems, programmer support for Window DLLs, C, C++, OS/2 and DOS is available.

    Installing the Example Digital Sampling Software

    Please read the README.TXT file to check for the latest update about PicDongle Digital Sampling before you begin installation of the Digital Sampling System.

    Making a Copies of the Program Diskettes

    The SiliconSoft PicDongle Digital Sampling example software is not copy-protected, so you can make backup or archive copies.

    Software Installation Process:

    To install PicDongle Digital Sampling Software on your computer follow the steps below:

    While you are in Windows, change to the drive that contains the SiliconSoft Digital Sampling diskette. If you are using the Program Manager, select File Menu and choose Run. Then type (for example if diskette is in drive A):

    A:SETUP.EXE
    and press Enter.

    Follow the instruction displayed on the screen.

    Installation of the SiliconSoft Digital Sampling Hardware:


    Select a COM port (normally the PC COM port connector is a DB25 plug).







    Connect the COM port cable to the PicDongle (refer to the labels on the PicDongle casing). To verify operation, start the example windows program and select the COM port you are using. While recording, touch pin 1 with a metal object. You should see the channel 1 indicator pick up a 60 Hz signal.




    To make a connection to the PicDongle be sure to read the bottom label and note the signal and ground pin numbers. Solder your wires to a DB25 receptical connector (pin 1 is channel 1, pin 2 is channel 2, etc., and pin 14 is ground). If the COM port is reset, the PicDongle's LED should be lit when the PC is on.



    Signal source connection to Pic Dongle

    Pic Dongle interface to host PC

    Connection to serial port with DB-25 pin connector















    Connection to serial port with DB-9 pin connector

    Connection for Macintosh port














    Warning Note:
    While the PicDongle is a robust design with fault condition protection for excess input voltages, as any electronic device, it can be damaged if it is misused or misapplied.
    For your protection and to prevent possible hardware damage - Turn off the power to your computer and any attached peripherals before continuing if you are not certain about the operation and use of the hardware you are using. Be sure to only use properly grounded AC line operated equipment. Do not use or connect together by cable any equipment that ungrounded and AC line operated. The PicDongle hardware is protected for over full scale input voltages (-0.5 V to 5.0 V or 10 mA maximum) but be aware that the DB cable connectors shells and shields and PicDongle chassis grounds are all connected to the common PC's chassis ground. If you have a noisy ground environment and low level signals you may want to use the inputs in a differential mode. That is, use one channel for the signal input and use the next channel to measure the ground voltage. Subtract the ground voltage value from the signal voltage to get the true signal value. Since the channel to channel sampling skew is a few microseconds, the noise subtraction works for frequencies up to ten KHz or more.

    1. Plug the PicDongle 12A digital sampling hardware directly into the desired serial port.

    2. Turn on the power to your PC and any attached peripherals.

    3. Start the example software or other COM or TERMINAL software and configure the hardware setup to 8 bits, No parity, 1 Stop bit at a 19,200 bps.

    When you select the port to which the PicDongle is connected and select Connect in the Dialog Box, you should see the data stream start. Normally the power required to operation the PicDongle is obtained from the RS232-E serial port. Some laptop or palmtop PC's may not have a standard power serial port and the PicDongle will not operate correctly. The LED should be lit on the PicDongle after it has been connected to a COM that has been reset (normally it's reset upon bootup) and it will stay on unless you toggle DTR 'high'.

    Use of the PicDongle 12A Hardware:

    The PicDongle 12A does not require any custom programming at the host PC. You can use any standard terminal program to view or capture the data stream from the PicDongle. However, if you want to directly control the data stream within your custom programm, see the PicDongle 12A Windows C example. While the example source code is for a C program compiled for Windows, it gives you enough information for use with other languages or computers with standard COM port support.

    The TTY Windows C sample program and source code is for use with Microsoft Visual C environment. This sample program demonstrates how to receive data from the PICDongle12A hardware using the COMM API. This program will accept data through the COM port from the PICDongle12A module.

    Install the PicDongle 12A by attaching it to any unused Serial port on you computer as covered in the previous pages. Run the TTY.exe sample program in Windows 3.1 or Windows 95. A window will be displayed with a menu bar with "Action", "Settings", and "About" menu items.

    1) Click on the Setting menu item to display the settings dialog box. Select the COM port of where the PicDongle 12A is attached. Check to make sure that the other settings are set as follows:

    Baud Rate: 19.2k Data Bits: 8 Parity: None Stop Bits: 1 Flow Control: None (all boxes are NOT checked). Also check the "Use CN_RECEIVE Notifications" box. Then press the OK button to save settings and remove dialog box.

    2) Click on the "Actions" pulldown menu item. Then click on the "Connect" item to start receiving data from the PicDongle 12A hardware. Click on the "Disconnect" item in the "Actions" pull down menu to stop receiving data.

    3) The data from the PicDongle 12A will be displayed in the TTY.exe Window in HEX format. The frame markers are also displayed.

    Example of output: 

    FFFF 0109 0108 0107 0106 0105 0104 0103 0102 FFFF 0101 0102 ...

    General Format: 

    FFFF xxyy xxyy xxyy xxyy xxyy xxyy xxyy xxyy FFFF ...
     LoHi LoHi LoHi LoHi LoHi LoHi LoHi LoHi 
Frame ch1  ch2  ch3  ch4  ch5  ch6  ch7  ch8 Frame  ch1

    The data stream from the PicDongle is continuous after power is applied by attaching the PicDongle to a COM port. There is a frame marker sent once every 8 channel samples or 16 bytes. The frame marker is 2 bytes of 0xFFFF at the start of each block of 8 samples (16 bytes) of sampled data.

    After the 2 bytes of 0xFF (frame marker: 0xFFFF), the sampled data is received in the PC as LowByte first then HiByte follows.

    For example, if the data stream looks like: 

    FF FF  01 00 02 00 03 00 04 00 05 00 06 00 07 00 08 00 FF FF ...
Frame  Lo Hi Lo Hi Lo Hi Lo Hi Lo Hi Lo Hi Lo Hi Lo Hi Frame ...

    One sample for each of the 8 channels are transmitted between the frame markers, from channel 1 through channel 8.

    For example, if the samples are: 

    FFFF 0109 0FFF 0000 0106 0105 0104 00FF 0102 FFFF 0101 0102 ...
      ch1  ch2  ch3  ch4  ch5  ch6  ch7  ch8      ch1  ch2 ...

    sample value for channel 1 is 0x0109 decimal value 265 mV
    sample value for channel 2 is 0x0FFF decimal value 4095 mV (full scale)
    sample value for channel 3 is 0x0000 decimal value 0 mV (zero)
    sample value for channel 7 is 0x0800 decimal value 2048 mV (half scale)
    sample value for channel 8 is 0x0BB8 decimal value 3000 mV

    Since the sampled data is 12-bits, the upper nibble of the HiByte will always be 0 unless it is a frame marker. The sample program prints out the sampled data to the screen in HEX 16-bit values.

    See the WriteTTYBlock function (in the sample file) for an example of how to check for frame markers and how to put the data stream byte values into 12-bit samples.

    The host computer's UART baud rate must be set to 19,200 so that it matches the fixed baud rate of the PicDongle 12A. Other settings are: 8 bits, 1 stop bit, no parity, no flow control.

    RxD, TxD

    These lines carry the data to and from the PicDongle; 1 is transmitted as 'mark' (what is called 'low' or -3 to -15 Volts ) and 0 is transmitted as 'space' ('high' or +3 to +15 Volts).

    RTS

    Is used by the PC (IBM, Mac, Sun or other RS232-E COM Port Card) and the modem/printer or PicDongle referred to as the data set, or DCE to start/stop the communications from the PicDongle. An RTS low stops the data stream. The PC sets RTS to 'high' ( logic 0) and the PicDongle data stream restarts.

    Increasing the Sample Rate:

    Although the PicDongle 12A's sample rate is fixed at 55.5 samples/sec for 8 channels you can increase the sample rate or bandwidth by tying channels together since each channel has a separate time slot:

    Channel      Jumpers      Effective Sample Rate (s/s)   Bandwidth (Hz)

   8           none                   55.5                   27.8
   4      1-5,2-6,3-7,4-8            111.1                   55.5
   2      1-3-5-7,2-4-6-8            222.2                  111.1
   1      1-2-3-4-5-6-7-8            444.4                  222.2

    Troubleshooting - Errors:

    A common problem with using the COM port is lost data or framing errors. If the host computer' CPU is not able to handle the COM port UART handshaking and move data from the COM buffer to RAM fast enough a COM error will occur. Try to give as much time as possible to service of the COM port and use a UART with a FIFO buffer.
    If you are having trouble connecting the PicDongle, this may help. 

    Contact:
SiliconSoft Inc.
www.siliconsoft.com
San Jose, CA  USA

Support Lines:
Email: siliconsoft@pacbell.net
Phone: (408)446-4521


    © Copyright 2000 by SiliconSoft Inc., San Jose, CA.