scannotec_metro_display

Scannotec metro display

Message frame

1. 0x82
2. 0x00
3. address byte
4. msg type byte

• Message might end here

1. length low byte
2. length high byte
3. data bytes
4. checksum

• Just a rolling 8bit sum of all bytes from step 5

The message length is the length of the data bytes payload and the checksum.

message types:

• 0x05 - set addresses
  • Payload is 2 bytes with the alternative addresses to listen to
• 0x09 - set RTC
  • Payload is 3 bytes, hours, minutes and seconds to set the time to
• 0x55 U - update display
  • Loads the payload to a 8000 byte buffer waiting to be processed, can be broken up into multiple messages
• 0x56 V - enable display
  • Triggers message processing
  • No timeout on the display
  • No payload, message processing ends at the msg type byte
• 0x57 W - enable display with timeout
  • Triggers message processing
  • Clears the display once a longish timeout expires
  • No payload, message processing ends at the msg type byte
• 0x81 - Ping?
  • Send ACIA flags
  • Triggers message processing
  • No payload, message processing ends at the msg type byte
• 0x87 - Trigger temperature measurement?
  • No payload, message processing ends at the msg type byte

Other messages will raise a error flag, but might still write to the 8000 byte buffer, needs to be verified...

content control characters

• 0x09 scroll text
  • two hex chars following, offset to start the scrolling in hex, - 0x4c, in pixels
• 0x0e small font
  • Confirmed
• 0x0f large font
  • Confirmed
• 0x11 set blink
  • Confirmed
• 0x12 reset blink
  • Confirmed
• 0x13 Enable dynamic content for the row
  • Scroller doesn't scroll or timers change unless this is present in the row data
• 0x14 timed messages
  • Two hex chars following.
  • Need to have multiple sections of different texts
  • Can have different content on each of them
• 0x15 4 char string substition
  • No idea what the contents are supposed to be, maybe temperature reading?
• 0x16 time of day substitution
  • 12:34
• 0x1b set active row
  • Rows start from 0x30 ->

• set_address: return
• V -> process all
• time_set: return
• rtc_something does something: return
• !W -> return

Memory map

• 0x0000 - 0x5fff Sram
• 0x6000 - 0x6020 memory mapped peripherals
• 0x7000 - 0x8000 Display ram
• 0xC000 - 0xFFFF Eprom

Memory mapped peripherals

• 0x6004 - 6821 PIA 1 data A
• 0x6005 - 6821 PIA 1 control A
• 0x6006 - 6821 PIA 1 data B
• 0x6007 - 6821 PIA 1 control B
• 0x6008 - 6821 PIA 2 data A
• 0x6009 - 6821 PIA 2 control A
• 0x600A - 6821 PIA 2 data B
• 0x600B - 6821 PIA 2 control B
• 0x6010 - 6850 ACIA control
• 0x6011 - 6850 ACIA data

Interrupts

• FIRQ: ACIA
• IRQ: PIAs
  • PIA 1
    • A
      • 1 - Unused counter 0-0x50
      • 2 - Unused counter, 16bit
    • B
      • 1 - Unused, does nothing
      • 2 - Frame sync, not on every frame...
  • PIA 2, only interrupt 1 enabled
    • A - Analog read stuff
    • B - Reads and stores lines

Bill of Materials

• EF68B09P - 6809 CPU
• HD63B50P - 6350 ACIA serial communications chip, externally clocked
• HD63B21P - 6321 PIA x2
• Memory
  • UM62256E-70LL - 32kb SRAM
  • GM76C28A-01 - 2k SRAM x4
  • 27C128 - 16kb EPROM
• 58321B - RTC
• LT1081CN - RS232 level shifter
• 6N139 - dual opamp
• CNY17-4 - optocoupler
• 74HC series logic; 26 chips
  • 74HC00 - quad 2 port NAND
  • 74HC01 - quad NAND, open collector
  • 74HC08 - quad 2 input AND 2
  • 74HC14 - hex inverter 4
  • 74HC27 - triple 3 input NOR
  • 74HC123 - dual retriggeable monostable multivibrator
  • 74HC138 - 3 to 8 decoder, active high
  • 74HC139 - 3 to 8 decoder, active low
  • 74HC151 - 8 input multiplexer x4
  • 74HC157 - quad 2 input multiplexer x3
  • 74HC245 - bidirectional bus transcriber x4
  • 74HC393 - dual 4 stage binary ripple counter
  • 74HC4040 - 12 stage binary ripple counter x2
• ULN2803A - darlington array
• 1.9152 MHz crystal - for ACIA
• 8.000 MHz crystal

• Jumpperit sarjapiirin läheellä valitsevat RX/TX tyypin