thanks for that inspiration!
I compared this solution carefully with mine.
That solution uses the trick, bluebie mentioned earlier in this thread, combining 5V and 12V into 1 pin.
However they make no additional use of it, as they don't use PB5, the digispark can use!
So I compared the usage of the pins (as well as the restrictions) of both solutions. In the first columns are the PINs of the master, in the following columns are the pins from the target, which are connected to the corresponding master-pin:
|Pin||name||digispark restriction||gogols solution||remark||bobricius inspiration||remark|
|1||PB5/RST|| ||12V ||12V-RST||not used ||not used |
|2||PB3 ||zener/pullup||PB3 (1k)||CLKOUT ||PB3 (direct) ||CLKOUT |
|3||PB4 ||zener ||PB1 (1k)||INSTOUT||5/12V ||Vcc and 12V|
|4||GND || || || || || |
|5||PB0 || ||PB0 (1k)||DATAOUT||PB0 (direct) ||DATAOUT |
|6||PB1 ||on-board LED||Vcc ||Vcc ||PB1 (direct) ||INSTOUT |
|7||PB2 || ||PB2 (1k)||DATAIN ||PB2 (330/LED)||DATAIN |
|8||Vcc || || || || || |
I could win one free pin for I2C, swapping the usage of PB1 and PB2 in my solution. I would however still need a solution for the second I2C-pin.
I could use the free pin for some indication via LED. However when I swap the two mentioned pins, I can do the same as in the inspiration-solution: Give some blink messages with the digispark internal LED. That is something I couldn't do with my pinout, as I would fire up the target controller together with the LED, which would cause several problems (depending on the program running there).
The target should only have power during HVSP-connections and otherwise not.
Furthermore the inspiration uses an 12V regulator, while I just use a cheap A23 12V-batterie.
Last are there no resistors between both attinys, where I have 1k resistors to prevent damage through shortages.
I will finish up the schematics and the code, when I have cleaned my workarounds.
The solution for now is just swapping the two pins, and defining some morse-like result codes, I will blink at the end!
As soon, as there is the bigger sibling available (http://digistump.com/board/index.php/topic,997.html
), I will continue my LCD-solution.