Microcontrollers (also μController, μC, MCU) are semiconductor chips containing a processor and peripheral functions. My favorite 8-bit MCUs are the AVRs from Atmel (now Microchip Technology). AVRs are programmed through an SPI interface called SPI (In System Programming). There are six unique signals and voltages required for the ISP communication: MOSI, MISO, SCK, Reset, VCC and GND.
An 'ISP Header' is the connector used to interface the cable which carries the programming signals from an external ISP Programmer to the target system circuit board (with the Microcontroller). On the one side there is a 2x5 female header and the other side a male 10-way box header. This pin assignment is an old pseudo-standard.
My often proven DIY programmer is a so called 'STK200/300 compatible programming adapter' for connection to the parallel printer port of a PC with a tri-state buffer chip (74LS244). Due to this IC, the controller can also remain connected to the programming adapter during operation. The adapter is supported by various software programs (including Bascom AVR-IDE).
However, today's PCs do not usually have an LPT/Centronics printer interface, but a USB port. There are simple solutions for this too, but my electronic workshop still has an old PC with the necessary old interfaces.
 DIY Programmer |
 Connections |
 AVR ISP Schematic |
 AVR ISP Connector |
 AVR ISP Pins |
