The built in power regulation circuit is designed to use any DC power source from 7.5V to 9V and supply 500ma of 5V current with passive cooling due to the very large heatsink attached. Input voltages up to 25V can be used, although active cooling with a fan may be necessary to reduce heatsink temperatures. A standard 2.1mm / 5.5mm power jack is onboard so standard wall wart power supplies can be used to power the board. Additionally, there is a DC PWR header which can be used to supply high voltage power from the wall wart directly to accessories. If no wall wart is used, unregulated power can also be applied to the DC PWR header to power the development board for easy installation in locations where unregulated DC power is already available.

The built in serial port circuit uses the industry standard MAX232 to provide the best compatibility with existing serial port devices. In addition to the standard Receive (RX) and Transmit (TX) lines, the Clear to Send (CTS) and Request to Send (RTS) lines are also available through a header so that the microcontroller can implement hardware flow control on the serial port. The serial port can also be disabled by removing the red jumper on the RS232 ENABLE header, which will free up the 2 IO pins used by the RX and TX lines if additional IO is needed on the development board. The circuit used is the same as in our FE_RS232 Serial Port Adapter board. Please see the description of the FE_RS232 Serial Port Adapter board for more details on the capabilities of the serial port.

One of the biggest disadvantages of using the internal RC oscillator is the inability to generate correct high speed serial port baud rates. We have incorporated an 18.432Mhz crystal oscillator circuit so that you can have a choice of running the microcontroller from the internal 128Khz clock, the internal 1Mhz clock, the internal 8Mhz clock, or from the external 18.432Mhz crystal oscillator circuit. These clock setting are selectable by programming the fuses on the microcontroller. When running using the 18.432Mhz crystal, the AVR can execute up to 18.432 million instructions per second. The 18.432Mhz crystal was chosen because it gives the best balance between generating industry standard serial port baud rates and high performance.

To take full advantage the features of the ADC on the AVR, an Analog Reference header has been provided which allows the easy hookup of a precision Analog Reference such as a high precision 4.096V reference to allow high precision ADC measurements for applications such as multimeters, gauges, or data sampling.

The IO ports brought out from the microcontroller have been layed out to be compatible with the layout of the STK500 IO ports. That means you can easily port your hardware accessories from the STK500 to the FE_M168 by simply unplugging the accessories from the STK500 and plugging them into the FE_M168. No need to rewire, solder, or deal with the messy wiring of solderless breadboards.

The FE_M168 uses the Atmel standard 6 pin ISP connector so that the FE_M168 can easily be programmed using the Atmel STK500, Atmel AVRISP, Atmel AVRISP2, or other third party programmers.

16kb Flash Memory
512 bytes EEPROM
1kb SRAM