DSP interface program for the VE2IQ COHERENT program. -------------------------------------------------------- Version 2.3 will now load with DL. I use it with Doug Braun, N1OWU's, BIOS2 loader in Flash and can recommend it. (I do experience some problems with using DL/BIOS2 on some of my computers, however, it seems to work reliably when used on a faster machine running Win95. Please contact N1OWU if this is a problem). Important Notes: 1) If you are planning on using the TAPR interface kit, you will need to make a couple of small changes to the program. This code presently uses PB8 and PB9 as inputs, the TAPR interface is using PB9 and PB10. 2) Included are a batch file "RUN.BAT" that I use to download and run Coherent. Edit it to suit your own purposes. I have had good luck running coherent in a DOS box in Win95, however do not switch consoles while Coherent is running as that will surely hang up Win95. If you do however, exit Coherent first, all is well. These notes are not complete; if you are not comfortable at building interfaces yourself and able to load software into the EVM, please get some help first. I am afraid these notes will not be sufficient for beginners, but there are several talented folks on the DSP net than can help - just ask. To get started with this BPSK project, obtain COHERENT from http://www.ietc.ca/home/bill/bbs.htm. Read Bill DeCarle's notes. To start the EVM side of things, a couple of helpful hints. 1) In previous notes, it was suggested to change the EVM's 4.0MHz crystal. This is no longer required. 2) COHERENT interfaces to the real world through a COM port. It receives digitized data at 115,200 BPS, and the characters are transmitted at a rate of 7200 per second, so make sure that your computer's serial port can handle this. In addition, PSK signaling is done by changing the state of the RTS line. If you wish, PTT control can be derived from the DTR line. The usual published interfaces on the TAPR web site for interfacing to the SCI port usually does not include any connections to the RTS and DTR lines - you would need to add this. The way I did this was to add a pair of RS232-to-TTL convertors on the EVM interface that change the RTS and DTR signals (on the SCI port only.) These level shifters can be someting really simple. I connect the RS232 line in question to a 10K series resistor feeding into the base of a 2N2222 or 2N3904 transistor. The base of the transistor is then protected by a 1N914 diode (cathode to the transistor base, anode to ground). The transistor emitter is grounded, and the collector is then taken via a 1K resistor to +5V. I then routed wires from the collector of each transistor to PB8 and PB9 corresponding to RTS and DTR respectively. 3) Notice that the RED LED will serve as your input overload indicator - it has been arranged that input overload at the EVM corresponds to the "CLIPPING" level for COHERENT. 4) The GREEN LED flashes at 1 second intervals. When you get your code loaded and running, check the accuracy of your EVM against the second ticks on WWV. It should hold time even for extended periods, however, if you can hold time for a few minutes, you are marginal, but it will work. If not, read the bit about replacing the ceramic resonator. 5) You may load this program using the EVM debugger, or use DL and Doug Braun's BIOS2. I have that in Flash and can recommend this. 6) If you place a RS-232 state monitor (available from Radio Shack) in line at the EVM, you will see that RTS is pulsing on/off. This tells us that COHERENT is up and running and is sending phase change requests to the EVM. Also note that DTR is like a keyboard VOX, controlled by the "MUTE" option. If you have MUTE=off, then you can switch back from transmit to receive by typing a "#" character. Note the use of the "END" key to start synchronizing, and the use of the "TAB" key to send sinchronization characters. 7) As a beginner - be forewarned that COHERENT takes a bit to get used to - so be patient and ask when you need help. Good Luck! Enjoy. Disclaimer: ----------- This program is provided "as is" and is intended for educational purposes only. The author(s) cannot be held resonsible for any mishap or accident resulting through the use of this software. --Use at your own risk-- This software is not to be used for any commercial application, military or government agencies without explicit written approval from author(s). Acknowledgements: ------------------ I am indebted to Pawel Jalocha, SP9VRC for many pieces of this code. Bill DeClarle, VE2IQ helped and assistance is appreciated. Thanks to Cliff Buttschardt, K7RR, and Bill Lake, WB6RIJ for the many wonderful QSO's and being patient elmers. Johan B. Forrer, KC7WW 26553 Priceview Drive, Monroe, OR 97456, USA July, 1997.