Co-Processor

[SkyNorth]

What are the basic functions should the Co-processor ship with?

Here is a schematic of the Co processor section , as well as the interface needed to program it.
(In the future we hope to be able to program it through the ARM chip.)

ERSKY9X-TINY167_WIRE.PDF

Co-Processor Wiring

(87.67 KiB) Downloaded 412 times

I was thinking of 4 A/D channels (pots) , 2 Rotary Encoders with push switches , and 2 , Three Way switches
The POTs and 3 way switches are on A/D channels , so they can be mixed between the two functions.

Thoughts?

-Brent

[cre8tiveleo]

I think that would be a perfect setup, just my thoughts.

[MikeB]

Once you select PB7(RESET) as an I/O line, you will disable the ability to use serial downloading as a programming method. We will 'have' to rely on a bootloader, and program via the I2C interface. It may be possible to use 'high voltage' serial programming, need to check the data sheet, but this is not supported by USBASP type programmers.
Can we keep the RESET(PB7) pin free?

Mike.

Edit: Just checked the data sheet, there is NO high voltage serial programming mode. If the RESET pin is disabled, and the bootloader fails, you will have bricked the chip.
How about using another of the analog inputs for BOTH rotary switches. Something like a 10K pull up, then one switch pulls down through 10K, and the other through 5K. Then decode 4 voltage levels to detect one or both switches on. (5V, 2.5V, 1.66V, 1.25V).

[Kilrah]

Bootloader is fine if the main processor can then program the coprocessor through I2C, no? That would be the most convenient, no extra programmer just to flash the coprocessor...

[SkyNorth]

Yes , the I2C bootloader would be perfect ...have you got it written yet?

I have been writing some Basic code in Bascom AVR for it , I was hoping to ship the board with some useful functions
pre-programmed into the chip.

I always forget about the "Reset" issue , if you disable it...

-Brent