26 October 2010

FT817 external display architecture

ATtiny or ATmega for the External Display? This is the question!

After I have fought with the tiny2313 to fit all requested features for the external display (for transverters), and lost ... after I have searched up and down the Net for the ATtiny4313 PDIP and realized that it is probably not yet in production ... I gave up.

The choice was whether to maintain backward compatibility with the stand-alone keypad based on ATtiny2313 OR establish a new standard, compatible with the "remote control" to-be.

While the ATmega chip can cost 3 times the ATtiny uC, it gives me much more freedom to produce something not only satisfactory, but fitting all the requirements. And leaves headroom for future extensions. Moreover a PCB drawn and produced for the display can be done for the keypad+display at the same time, just leave out components when assemblying.

So, ATmega48/88/168 is the final choice. Probably an ATmega48 will suffice.

In any case I will not throw away the ATtiny2313 external display firmware for those who have built the circuit published in the last month (October 2010). It will be available on request.

In any case the 2*16 LCD display based on HD44780 controller will not change.

21 October 2010

Survey on your microwave equipment

The interaction with an active microwaver has been very instructive and helpful for the development of my external display firmware. But I would like to hear also other opinions.

I have arranged an online survey in three questions. It's anonymous but will help me gather a broader overview on the microwave "land".

Please spend two minutes with my survey. I can leave it running for 10 days, so until October 31st, 2010.

I will publish aggregate results here once the survey is over.

Thank You!

19 October 2010

Short-term projects, end of 2010

For the short-term period, let's say end of 2010, I have the following shack-wishes to achieve:
  • Design and test an ATmegaNM stand-alone fuse restorer
  • Design and build an HF/4m transverter (TX-only)
  • Assemble a keypad+display prototype on perfboard
I think I had planned something more, but I don't remember it :-)

11 October 2010

External display for transverter use - one more update

One more update to the firmware and diagram of the external display for transverters. Since there was a little bit of program space left, I added the support for a VFO A/B swap button.

Now you need two N.O. pushbuttons and one DPST switch.

If you don't want the A/B function, leave out the pushbutton but do insert the 10k pull-up resistor. Same for the dual LO, just put a pull-up resistor between pin 12 and 5Vcc if you won't be using a transverter with input into the UHF region.

10 October 2010

FT817 external display for transverter, updated

101010: I have managed to "sign" this date with a new (internal) firmware version for the external display for transverter users.

The new firmware allows L.O. values for 10 GHz (and more) transverters. The programming occurs as announced before, reading the display frequency and interpreting it as GHz instead of MHz.

But two L.O. frequencies can be stored, one to be used when the 817 (857, 897) is tuned to HF/VHF and another for UHF. According to a microwave experimenter, with this option it is possible to use 10 and 24 GHz transverters. UHF is recognized automatically by the display, and L.O. value varied accordingly.

Since automatic band recognition is enabled, there is also an output pin switching high from HF/VHF to UHF in order to switch transverters! One radio, one external display, two transverters! All within an ATtiny2313.

Here is a preview on the schematic diagram. Firmware will be published on the usual website. But it's available on request since now.

PS: this firmware works on FT817, FT857 and FT897, and their ND versions.