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MajorCore development boards

In order to develop a system around a microcontroller, you sooner or later need a test environment. Such environment may be a breadboard, but also a dedicated dedicated development board. I'm going to present to you two development boards that lets you burn the bootloader and upload your program using a USB to serial adapter.

Atmel's STK500

The STK500 development board was released by Atmel in the early 2000s, and has a ton of great features! It's been the ultimate development board for more than a decade because of its versatility, flexibility and excellent price point. If you don't know the STK500, let me sum it up for you:

  • It got an onboard programming interface (called stk500), that comminicates with a computer using a serial interface (RS-232)
  • The board lets you control the operating voltage, clock frequency, analog reference voltage in software using avrdude or Atmel Studio
  • It's powered from an external 12v adapter
  • It supports almost all AVR microcontrollers that comes in a DIP package.
  • All the IO pins are broken out
  • It got eight on-board LEDs and buttons for testing
  • It got an aditional serial port for serial communication with the microcontroller

Burning the bootloader using the STK500

Let's prepare the STK500 for some bootloader action!

  • Insert your microcontroller (ATmega8515 or ATmega162) in the socket called SCKT3000D3, and make sure it's installed the correct way.
  • Insert a crystal in the crystal socket if you're not using the internal oscillator.
  • Make sure the XTAL1 jumper is connected, that the OSCSEL is connected between pin 2 and three as shown in the picture below.
  • Connect the 6 pin cable between the ISP6PIN and the SPROG3 connector. This will connect the stk500 programmer to the microcontroller.
  • Connect the 10 pin cable between the PORTB and LEDS header (optional but recommended).
  • Connect the 2 pin cable between the RS232 SPARE and the PORTD connector. The RXD pin should be connected to PD0, and the TXD pin should be connected to PD1.
  • Apply power to the board.
  • Open Arduino IDE, select the correct clock frequency option and the USB to RS-232 adapter you're going to use.
  • Select the STK500 as ISP option in the programmers menu.
  • Connect the RS-232 adapter into the RS232 CTRL connector on the STK500
  • Hit Burn Bootloader!

If everything is allright, LED0 should now flash twice every second.


STK500 top view

Uploading code using the serial interface

Now that the bootloader is burnt, it's time to "Arduinoize" the STK500 by uploading code using a serial interface! By default the STK500 doesn't support auto reset, which the bootloader relies on. To add this feature we need to do some soldering. It's a fairly simple fix, and it actually let's you use the STK500 with other microcontrollers (MightyCore, MiniCore, Microcore) in Arduino IDE as well. This is how it's done:


Flip your board around and locate the RS232 SPARE connector. Solder a 100 nF capacitor to pin 4 on the connector. This is the DTR pin. Solder a wire from the other end of the capacitor to the RESET pin on the SCKT3000D3 socket. I chose to use a 0805 capacitor. STK500 top view


To prevent damage to the RESET pin caused by undervoltage from the RS-232 interface, a diode needs to be solder between ground and RESET. I soldered a 1N4007 SMD diode near the EXPAND0 connector.
Then you have to disconnect the RESET jumper marked in red on the first picture. If not, auto reset will not work. The last thing on the list is to remove the 6 pin connector.

Now open Arduino IDE, select the correct clock frequency and serial port, and simply hit Upload. Your code should now be running on the microcontroller!


STK500 bottom view 1
STK500 bottom view 2

ReadyAVR-40

The ReadyAVR-40 development board is combined development board that supports both MajorCore and MightyCore compatible microcontrollers. The board has a built in CP2102 USB to serial converter, so it's more convinient than the STK500 if you're planning to use the serial interface. Just make sure the PD0 and PD1 jumpers are connected.


ReadyAVR


This board doesn't got auto reset, so a similar fix is required for this board as well. Simply solder a **100 nF** capacitor to pin 28 on the CP2102 chip (red arrow on the first picture), and solder a wire from the other end of the capacitor to the _RESET_ button.