Hi Ken, Kurt,
Thanks for the quick response! This "hot rod" of the Mark III sounds like it could certainly work!
I did notice that it was the RTS/CTS lines that had the convenient jumpers, not the TX/RX which would have to be cut (and the extra parts added), but we can do that. The Mark III has a 1K RES line pull-up which might have to be changed also (as the Nano programming interface specifies 10K).
Do you know if there be a Nano 40X choice in the IDE (or a way to specify the different clock rate)? I can just fudge the baud rate, but the delays and other (PS2?) timing will probably be affected.
Kurt,
Do I remember that you have the Nano development board? Could you measure the board overall size, and the center-to-center distances of the mounting holes?
Thanks!
Alan KM6VV
kenjj wrote:
Hello, Allan.
Sure, why not? If you use the Nano40, disconnect the crystal circuit. This gives you two more I/O pins where the clocks used to be, P32 and P33. Select Nano/Nano40 from the selection menu.
If you use the new Nano40X you could keep the 20MHz crystal circuit in and run 2.5x faster than the Nano40. This means everything, including the serial ports, runs faster.This is probably the old Atom chip, so select Atom/ BasicAtom40 RevD from the selection menu.
As for programming, you can just keep the present MAX232 chip and use a standard serial port or a USB-serial adapter IF the adapter supports RTS to supply the RESET. Get the Nano40 data sheet and check out pages 5 and 6 of the PDF. This shows how to merge the TxD and RxD from the MAX232 through a diode, and using a 10k pullup, to arrive at the single-pin programming/serial pin at the processor's pin 6. This pin is refered to as S_IN or S_OUT for serial comms.
Hope that helped.
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