HACKADAY SUPERCONFERENCE BADGE, Manual

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2.3.2. DATA RAM ORGANIZATION
Kernel uses Data RAM GPR (General Purpose Register) area locations 0x000...0x029 for
housekeeping registers. Locations 0x600...0737 are used for special purpose.
addr name bit description
0x00 KeyEdge 0 = set by kernel if key INT edge detected (user must clear)
1 = set by kernel if key LEFT edge detected (user must clear)
2 = set by kernel if key UP edge detected (user must clear)
3 = set by kernel if key DOWN edge detected (user must clear)
4 = set by kernel if key RIGHT edge detected (user must clear)
5...7 Not used
0x01 Rotor0 Used for key INT debouncer (rotate left, bit = 0 if key pressed)
0x02 Rotor1 Used for key LEFT debouncer (rotate left, bit = 0 if key pressed)
0x03 Rotor2 Used for key UP debouncer (rotate left, bit = 0 if key pressed)
0x04 Rotor3 Used for key DOWN debouncer (rotate left, bit = 0 if key pressed)
0x05 Rotor4 Used for key RIGHT debouncer (rotate left, bit = 0 if key pressed)
0x06 Flag 0 = set by kernel: Pause mode, clr by kernel: Run mode (do not modify)
1 = Timer 0 interrupt (1200 Hz) handshaking (user must reset)
2 = Full display scan (150 Hz) handshaking (user must reset)
3 = set: EEPROM RX buffer function disabled (set/clr by user)
4 = Timer 0 interrupt in 2nd phase (LED OFF period) (do not modify)
5 = set: Disable pause mode
6 = Flag that display message was received (user must reset)
7 = Not used
0x07 RXFlag 0 = set: Enable RX to RAM 0x601...0x6FF and EEprom (set/clr by user)
1 = set: RX header reception is in progress (do not modify)
2 = set: RX message reception is in progress (do not modify)
3 = set: RX message received (internal use, do not modify it)
4...7 Not used
0x08 Brightness Display PWM, user presets to 0...15 for dimming
0x09 GPreg General purpose register, may be used by user
0x0A Anode Count display multiplex column counter 0...7
0x0B BitMask
10000000...00000001, shift reg used for anode scan
0x0C T0period Total Timer 0 period, may be modified to alter scan frequency
0x0D InnerInt Loop counter, used by interrupt routine
0x0E OuterInt Loop counter, used by interrupt routine
0x0F OuterPlusInt Loop counter, used by interrupt routine