ISP Programmer for ATmega32 Microcontroller

So far I’ve discussed about the micro controller and the compiler software. I’ve yet not written anything about programming.

ATmega32 series micro controllers support 3 types of programming

•   Parallel Programming
•   ISP Programming or serial Programming
•   Programming via JTAG

Here ISP stands for In System Programmer. To burn a micro controller just the burning Hardware is not enough, it requires software also that would download the program present in a computer or memory device into the micro controller.

                Now the software which I am concerned about is named PONY PROGRAMMER 2.06. My circuit is adapted from its website. It uses PC COM PORT to download the program into the micro controller. It have signal amplitude of +5 to +12 volt representing binary ‘1’ and -5 to -12 representing ‘0’.

                The micro controller, ATmega32 is programmed using the pins meant for SPI communication. To enable programming, the microcontroller is taken to the RESET state by pulling its reset pin LOW (Logic 0, or say 0 V), in this state, microcontroller is programmable in either mode (Parallel programming and serial programming). Micro controller always accepts 0 V as logic 0 and +5 V as logic one.

                So as I’ve described before, there is a mismatch between the signal transmitted by PC and signals accepted by the micro controller. Signals are made suitable for micro controller. In the programmer, Zener diodes provide necessary conditioning of the signals. It is so attached that it converts ±12 volt signal to +5-0 volt signal which is suitable for the micro controllers.  A resistance is necessary to limit the current in the nodes of Zener diodes, without the resistors, the voltage can burn the Zener diode, and computer internal circuits may also receive harms.

A high signal (+5V) in the ‘Reset’ pin of micro controller brings it into operational state. A low signal (Ground) drives it into programming mode. As internal pull up resistors are provided at the reset pins, so if nothing is connected to this pin, the micro controller tries to execute the program written within it. Designers may provide a resistance capacitance reset circuit, but it’s not always necessary. Whatever, a push button is used most of the time to provide reset facility. Here in the burner circuit, an open collector output is provided to the reset pin, it is driven by the programmer through the port. This much is enough.

                                                  circuit diagram of ISP PROGRAMMER

 The necessary data transmission and reception work portion is handles by the pony programmer. Follow the links provided to download pony programmer. The following burner circuit can burn ATmega32 microcontroller, connect the derived signals to the adjacent pins, attach the cable to com port, power up the device i.e. micro controller, and the micro controller is ready to be programmed.