Now, since TSB firmware software is examined at assembler level, I'm looking for decent One-Wire adaptor for the Host, often referred to as "CI-V" interface to connect my MPU pin and test TSB after flashing generated TSB firmware HEX to Attiny85 MPU and started with this Icom CI-V interface:
http://www.qsl.net/g3vgr/civ.html .
However, to use it with 5VCC or 3.3VCC powered MPU I need 5V/3.3V voltage regulator between D1 and C1 capacitor, I guess, since typical voltage levels on DB9 might destroy my MPU input ports?
I've made simple SMD prototype circuit fro DB9 male connector according to schematics at linked page above, but havent got time to test it...
Not sure, what D2 diode does? My guess is it protects Q1 NPN transistor emiter reverse voltage to stay at safe levels ?
Anyway, main concern is voltage output on Tip pin when Db9 pin 3 transmit data is low ... another story is some USB to RS-232 converters eg. based on not FTDI but silimar Silicon Labs CP210x USB to UART chips I have - probably voltage levels in such converter will not go above 5V at pin 1 , 4, 6 which are connected in this design?
Now thinking on something different.. maybe old good voltage level shifters used in I2C interface between output Tip and my MPU powered at 5v or maybe even 3.3V, however I prefere 5V for Attiny85 since I usually switch at the begining odf the program to internal 16MHz oscilator from default one used for flash programming, etc...
What do you think, howto connect such dongle with respect to corrent voltage levels to 5V/3.3V Attiny85 MPU for one-wire TSB working with different USB to RS-232 converters and oryginal DB9 PC female ports available?
Now, I like idea of voltage levels shifting but what do you think about it?
Galvanic separation not needed for the moment - my concern is correct voltage levels to do not burn MPU input port used for one-wire TSB as well as data echange using custom one-wire protocol.
Regards.
Bedu.