Saturday, 7 January 2017

RT-320 Controller - Major setback


And it was all going so well!.

Yesterday, I 'presented' the Arduino Mega board to the RT-320 to gauge the fit - and it doesnt!

In the photo above, you can see where the board has to go, its in the space between the turret and the filters/PSU module. Essentially, the slot down the middle.
So its back to the drawing board.
On another note, the 2nd 24v SMPSU went back, and was refunded with no problem whatsoever. The seller, Makershut, was appolgetic and promised to discuss the issue with their supplier. All in all very pleased with their response.

So, how to deal with the RT-320 space issue? One idea im considering, whilst trying to stay with the Arduino route, is whether the space is sufficient to hold a pair of Nanos? Maybe side by side, or perhaps built as a sandwich? A Nano has 14 Digital I/O lines, and 8 Analogue. Two of the DIO pins are used for dedicated serial comms.

But, heres a trick! The Analogue pins can be used as ordinary digital pins! So thats 22 DIO lines available.

Now, for this project I need a bare minimum of 20 lines, thats if I only read and write the sub-MHz. In order to read the 10 and 1MHz switches as well, I need 26 lines (one of which controls switching the supply line). Perhaps add an Analogue input to read the AGC line to provide a signal meter as well - 27 lines. A minimum 2, probably 4 lines for serial comms, and then another 2 lines for I2C comms between the two Nanos...

...getting complicated! But im sure the Nanos and the comms are all capable of operating far faster than a human can change a setting.

I believe I can use just 2 lines for RS232 (TxD, RxD and GND), so 2 DIO pins for the Master Nano comms (2x RS232, 2x Analogue [A4,A5] I2C). That leaves 12 DIO lines on the Master. Two Analogue lines for I2C on the Slave Nano leaves me 14 DIO lines. If we figure that the most likely lines to change rapidly are those of the 100Hz and 1kHz switches, thats 9 DIO lines. This means that the I2C, RS232, 100Hz, 1kHz, and the switch Vcc control, can all be done on the Master Nano, without having to resort to using any more Analogue pins than the I2C. The AGC input can go to the Master A0 input, and the LOCK tone to A1. This means that the Slave Nano, with pins A4 and A5 used for I2C comms to the master, would have the 10kHz, 100kHz, and 10MHz switches on its remaining DIO lines, with four of its Analogue lines repurposed as DIO to read the 1MHz switch. This would leave 4 spare analogue lines on the Master, and 2 spare analogue on the Slave.

Of course, all this relies on the available space being able to fit the two boards!

If it can, then it is certain that I will need an experienced programmer to write the software!

The Remote module, if using a Nano, will fit all basic, and some advanced, functions on the DIO pins - A4, A5 I2C to an EEPROM for frequency memories/split/A-B VFO etc, D0, D1 for RS232, 6 DIO lines for the LCD, and 2 DIO for a rotory encoder. The LOC/REM switch, UP, DWN, SELect, VFO/MEM, and SPLIT/A-B VFO functions can share DIO and some Analogue pins used as DIO.

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