Echo_hsn

i’ve created new post because i needed another clean page to include the final pcb of this this week

please check the design work flow page

Schematic Design:

this is the schematic design:

Component Selection:

• MCU attiny44

• Resistors:

  • R1 this resistor will control the charging speed of the
    capacitor C4 -> 10K Ohm

  • R4 this resistor will limit current to prevent LED rush current:
    minimum 330 Ohm

    5v - 1v(accros led) / 330 ohm < 12 mA

  • R5 0ohm just jumper

  • R6 pullup resistor, this drive the reset high to prevent mcu from reseting
    and limit the current when the programmer short it to ground…

  • R7 to control the discharge of C4 when the button unreleased this resistor
    provide path to discharge capacitor, 10k Ohm

  • C4 this capacitor will charge and discharge when the button (pressed/released)
    100nF

Pcb design:

this is the final pcb .. for technical details you can view the

#PCB design

Design Considerations and tips

#design-considerations-and-tips

v1 tx - rx

v1 programming