USB-programmer (AVR): description, purpose

At radio technicians who like to be engaged in the design of electronic devices, from time to time there is a need to use microcontrollers in their development. The use of these semiconductor devices Opens great prospects for radio technicians. Microcontrollers are produced by only a few companies, the leaders of which are MicrochipTechnology, ATMEL, ARMLimited. The main feature of such devices is the need for their software firmware. For this, programmers are also needed. To date, there is a huge selection of different types of programmers, however, the price of such products is very high, and not every radio amateur can afford to purchase such a device.

In this article, we'll look at the USB-programmer (AVR) based on the Atmega 8 control microcontroller. This product is quite simple, so that the ham radio can assemble it on its own and do not spend a lot of money on the branded product. The USB-programmer (AVR) chosen by us has a minimal strapping of the microcontroller, which allows assembling a very miniature device. This product does not take up much space, it has the overall dimensions of an ordinary flash drive. The USB-programmer (AVR) in its scheme contains the microcontroller Atmega 8, the type of the case is TQFP 32 (it should not be confused with the type of the DIP case, as they have different pinouts). A diagram of such a device is shown in the photo.

Let us proceed to a description of the scheme of the device. Jumper J1 is used in the case when it becomes necessary to flash a microcontroller having a clock frequency below 1.5 MHz. If desired, this jumper is easily excluded from the circuit, for this purpose, the controller's 25th pin sits on the ground. In this case, the AVR-USB programmer will always function at a reduced frequency. It should be noted that programming at a low frequency takes longer, but it's up to you, of course. Zener D1, D2 are used to match the level between the USB bus and the programmer. The blue LED indicates that the device is ready for programming the microcontroller, the red diode is lit during programming. The circuit has an IDC-06 connector, to which contacts are pin-out, whose pinouts correspond to the ATMEL type of the 6-pin ISP connector. On the indicated connector the power contacts of the microcontrollers are output, it is taken from the USB port of the personal computer, therefore, it is necessary to be careful not to allow a short circuit. With the same connector, the controller and the controller are also programmed, it is necessary to connect the Reset contacts on the controller and on the connector (in the diagram it is shown in red dotted lines). The jumper for reducing the speed of the programmer and the connector for connecting the microcontroller are located on the end of the device. That's what a USB-programmer (AVR) is, as you can see, everything is elementary.

After the device is assembled, it is necessary to flash the controlling microcontroller, for this I recommend using the PonyProg program. When programming, we start the crystal for operation from an external clock source at 12 MHz.

The USB-programmer for AVR described in this article works with all microcontrollers such as AVR, allows to flash them, look at the recorded contents of the device, erase chips, change the configuration.