microcontroller chips

microcontroller chips appear on the market, today’s microcontroller programming tools are becoming more and more ‘universal’ to cope with different programming conventions. It is also sadly the case that the more ‘universal’ the programmer, the more you need to pay. In practice, most people will only use a fraction of the capabilities of such a programmer, making it difficult to justify such an expense. The project here describes a minimal solution to the programming problem for one of the most popular types of controller. The PIC16F84 (1k-Flash-memory) and the PIC16C84 (1k-ROM) with 13 I/O-lines.

Using a PC together with this relatively simple interface and some software it is possible to build a low cost programmer The design for the programmer is described on the author’s website. The programmer connects to the serial port of a PC. Pin 3 of the port supplies the power and zener diode D6 along with D5 regulates the supply to the chip at 5 V. C1 and C2 smooth the regulated supply. The unregulated supply is fed to pin MCLR of the PIC to configure it in programming mode. R1 limits current into this pin and an internal regulator ensures the correct programming voltage on chip. A high on this pin switches the PIC into programming mode.

Data exchange between the PC and the PIC occurs over the lines TxD (Pin 3), DTR (Pin 4) and CTS (Pin 8) and can be viewed on the LEDs D2, D3 and D4. A control software package comprising NTPICPROG, PIX and Euro13 for Windows and DOS (altogether 198 kB) can be downloaded free from the ‘Elektro’ page of the authors website at