Inputs are green, and green dots may only be connected to other green dots.
Outputs are red, and red dots may only be connected to red dots.
Black dots are ground, and black dots may only be connected to other black dots.
LED's must be driven by transistors or buffers.
LED's must consume less than 20 mA total or the port will be overloaded.
You must take care not to power too large a circuit from the port.
The target microcontroller may provide it's own power.
The target power supply voltage must be the same as that of the parallel port.
The parallel port forms an SPI serial interface to the chip.
This example uses most of the signals. The only signal not used is 'buff', which is used to enable tri-state buffers. The
only signals required are the ones on the ISP connector. The LED signals are completely optional.
Add a transistor circuit for each of the LED's (up to four):
Or use an open drain (or collector) buffer to drive the LED's:
Add the ISP connector:
Then create a programmer entry for avrdude in the avrdude.conf file: