Board attiny45

This is just a ATTINY45-20PU on a breadboard with a USB/Serial adapter and a LED connected at pin #5 (PB0/OC0A). No crystal.

The serial communication uses 1 wire for RX/TX, AVR pin #2 connected to the RXD pin of the serial adapter, and a 1k resistor is connected between the RXD and TXD pins (it could be replaced by a diode, Schottky preferably).

TINY45 ->  2 : RXD <- Serial Adapter
             : TXD
           1 : DTR
           4 : GND
           8 : VCC

To install Diabolo with avrdude/usbasp:

 USBASP -> 1  MOSI  5 <- TINY45
           2  VCC   8
           4  GND   4
           5  RST   1
           7  SCK   7
           9  MISO  6

attiny45.h

 
/*  This file is part of the HWA project.
 *  Copyright (c) 2012,2015 Christophe Duparquet.
 *  All rights reserved. Read LICENSE.TXT for details.
 */
 
/*  Device configuration
 */
#define HW_DEVICE_CLK_SRC               rc_pll_16MHz
#define HW_DEVICE_CLK_PSC               1
#define HW_DEVICE_EXTERNAL_RESET        enabled
#define HW_DEVICE_SELF_PROGRAMMING      enabled
#define HW_DEVICE_DEBUG_WIRE            disabled
#define HW_DEVICE_WATCHDOG_ALWAYS_ON    no
#define HW_DEVICE_CLOCK_OUTPUT          disabled
#define HW_DEVICE_BROWNOUT_DETECTION    4100_4500mV
 
/*  Settings for building the Diabolo bootloader
 *  Settings for the Diabolo application are in the board's Makefile
 */
#define DIABOLO_PIN_RX                  (pin,2)
#define DIABOLO_PIN_TX                  (pin,2)
#define DIABOLO_SYNC                    51
 
/*  The pin at which the LED is connected. The target device name indicates its
 *  package, then pin numbers can be used as well as pin names.
 */
#define PIN_LED                         (pin,5) // OC0A
 
/*  Include HWA definitions
 */
#include <hwa/attiny45_20pu.h>