User`s manual

Chapter 4: Hardware Descriptions
The crystal frequency is 16 MHz and usually it will result in an 8 MHz bus speed, but on this board the
MC9S12DG256’s internal PLL boosts the bus speed up to 24 MHz.
The circuits are designed in such way that the value of all resistors and capacitors are not critical and
they can be off -50% or +100%.
4.1 Power LED:
The power LED is made of the decimal point of the 7-segment display. It will always be lit when
power is applied.
4.2 Pushbuttons:
The two pushbuttons (S1 and S2) are connected to AN04 and AN03.
S1----- AN04
S2----- AN03
4.3 Seven-Segment LED
The type of the 7-segment LED on the MiniDragon Plus3 board is called common anode. All
cathodes are driven individually by an output port and all anodes are internally connected
together.
The MiniDragon-Plus3 board uses port H to drive 7-segment cathodes. We will explain how to
flash the number 1234 on the display
Before sending a number to a 7-segment LED, the number must be converted to its
corresponding 7-segment code depending how the 7-segment display is connected to an output
port.
Note: The original MiniDragon+ board employs a common cathode LED display, but it’s
changed to common anode on the MiniDragon Plus3 board. For software compatibility
purpose, we pretend that the new MiniDragon Plus3 board still uses a common cathode LED
display and we just need to add an instruction ‘coma’ to invert data before outputing it to port H
for driving a common anode LED display.
By convention, the 7 segments are called segment A, B, C, D, E, F. and G. Their locations in the
display are shown below:
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